rfc9692.original   rfc9692.txt 
RIFT Working Group A. Przygienda, Ed. Internet Engineering Task Force (IETF) T. Przygienda, Ed.
Internet-Draft J. Head, Ed. Request for Comments: 9692 J. Head, Ed.
Intended status: Standards Track Juniper Networks Category: Standards Track Juniper Networks
Expires: 24 November 2024 A. Sharma ISSN: 2070-1721 A. Sharma
Hudson River Trading Hudson River Trading
P. Thubert P. Thubert
Bruno. Rijsman B. Rijsman
Individual Individual
Dmitry. Afanasiev D. Afanasiev
Yandex Yandex
23 May 2024 December 2024
RIFT: Routing in Fat Trees RIFT: Routing in Fat Trees
draft-ietf-rift-rift-24
Abstract Abstract
This document defines a specialized, dynamic routing protocol for This document defines a specialized, dynamic routing protocol for
Clos, fat tree, and variants thereof. These topologies were Clos, Fat Tree, and variants thereof. These topologies were
initially used within crossbar interconnects, and consequently router initially used within crossbar interconnects and consequently router
and switch backplanes, but their characteristics make them ideal for and switch backplanes, but their characteristics make them ideal for
constructing IP fabrics as well. The protocol specified by this constructing IP fabrics as well. The protocol specified by this
document is optimized toward the minimization of control plane state document is optimized towards the minimization of control plane state
to support very large substrates as well as the minimization of to support very large substrates as well as the minimization of
configuration and operational complexity to allow for simplified configuration and operational complexity to allow for a simplified
deployment of said topologies. deployment of said topologies.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 8 1.1. Requirements Language
2. A Reader's Digest . . . . . . . . . . . . . . . . . . . . . . 8 2. A Reader's Digest
3. Reference Frame . . . . . . . . . . . . . . . . . . . . . . . 10 3. Reference Frame
3.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 10 3.1. Terminology
3.2. Topology . . . . . . . . . . . . . . . . . . . . . . . . 16 3.2. Topology
4. RIFT: Routing in Fat Trees . . . . . . . . . . . . . . . . . 19 4. RIFT: Routing in Fat Trees
5. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5. Overview
5.1. Properties . . . . . . . . . . . . . . . . . . . . . . . 19 5.1. Properties
5.2. Generalized Topology View . . . . . . . . . . . . . . . . 20 5.2. Generalized Topology View
5.2.1. Terminology and Glossary . . . . . . . . . . . . . . 20 5.2.1. Terminology and Glossary
5.2.2. Clos as Crossed, Stacked Crossbars . . . . . . . . . 21 5.2.2. Clos as Crossed, Stacked Crossbars
5.3. Fallen Leaf Problem . . . . . . . . . . . . . . . . . . . 31 5.3. Fallen Leaf Problem
5.4. Discovering Fallen Leaves . . . . . . . . . . . . . . . . 33 5.4. Discovering Fallen Leaves
5.5. Addressing the Fallen Leaves Problem . . . . . . . . . . 34 5.5. Addressing the Fallen Leaves Problem
6. Specification . . . . . . . . . . . . . . . . . . . . . . . . 35 6. Specification
6.1. Transport . . . . . . . . . . . . . . . . . . . . . . . . 36 6.1. Transport
6.2. Link (Neighbor) Discovery (LIE Exchange) . . . . . . . . 36 6.2. Link (Neighbor) Discovery (LIE Exchange)
6.2.1. LIE Finite State Machine . . . . . . . . . . . . . . 42 6.2.1. LIE Finite State Machine
6.3. Topology Exchange (TIE Exchange) . . . . . . . . . . . . 52 6.3. Topology Exchange (TIE Exchange)
6.3.1. Topology Information Elements . . . . . . . . . . . . 52 6.3.1. Topology Information Elements
6.3.2. Southbound and Northbound TIE Representation . . . . 53 6.3.2. Southbound and Northbound TIE Representation
6.3.3. Flooding . . . . . . . . . . . . . . . . . . . . . . 56 6.3.3. Flooding
6.3.4. TIE Flooding Scopes . . . . . . . . . . . . . . . . . 65 6.3.4. TIE Flooding Scopes
6.3.5. RAIN: RIFT Adjacency Inrush Notification . . . . . . 70 6.3.5. RAIN: RIFT Adjacency Inrush Notification
6.3.6. Initial and Periodic Database Synchronization . . . . 70 6.3.6. Initial and Periodic Database Synchronization
6.3.7. Purging and Roll-Overs . . . . . . . . . . . . . . . 70 6.3.7. Purging and Rollovers
6.3.8. Southbound Default Route Origination . . . . . . . . 71 6.3.8. Southbound Default Route Origination
6.3.9. Northbound TIE Flooding Reduction . . . . . . . . . . 72 6.3.9. Northbound TIE Flooding Reduction
6.3.10. Special Considerations . . . . . . . . . . . . . . . 77 6.3.10. Special Considerations
6.4. Reachability Computation . . . . . . . . . . . . . . . . 78 6.4. Reachability Computation
6.4.1. Northbound Reachability SPF . . . . . . . . . . . . . 79 6.4.1. Northbound Reachability SPF
6.4.2. Southbound Reachability SPF . . . . . . . . . . . . . 80 6.4.2. Southbound Reachability SPF
6.4.3. East-West Forwarding Within a non-ToF Level . . . . . 80 6.4.3. East-West Forwarding Within a Non-ToF Level
6.4.4. East-West Links Within ToF Level . . . . . . . . . . 80 6.4.4. East-West Links Within a ToF Level
6.5. Automatic Disaggregation on Link & Node Failures . . . . 80 6.5. Automatic Disaggregation on Link & Node Failures
6.5.1. Positive, Non-transitive Disaggregation . . . . . . . 80 6.5.1. Positive, Non-Transitive Disaggregation
6.5.2. Negative, Transitive Disaggregation for Fallen 6.5.2. Negative, Transitive Disaggregation for Fallen Leaves
Leaves . . . . . . . . . . . . . . . . . . . . . . . 84 6.6. Attaching Prefixes
6.6. Attaching Prefixes . . . . . . . . . . . . . . . . . . . 86 6.7. Optional Zero Touch Provisioning (RIFT ZTP)
6.7. Optional Zero Touch Provisioning (RIFT ZTP) . . . . . . . 94 6.7.1. Terminology
6.7.1. Terminology . . . . . . . . . . . . . . . . . . . . . 95 6.7.2. Automatic System ID Selection
6.7.2. Automatic System ID Selection . . . . . . . . . . . . 97 6.7.3. Generic Fabric Example
6.7.3. Generic Fabric Example . . . . . . . . . . . . . . . 97 6.7.4. Level Determination Procedure
6.7.4. Level Determination Procedure . . . . . . . . . . . . 98 6.7.5. RIFT ZTP FSM
6.7.5. RIFT ZTP FSM . . . . . . . . . . . . . . . . . . . . 100 6.7.6. Resulting Topologies
6.7.6. Resulting Topologies . . . . . . . . . . . . . . . . 105 6.8. Further Mechanisms
6.8. Further Mechanisms . . . . . . . . . . . . . . . . . . . 106 6.8.1. Route Preferences
6.8.1. Route Preferences . . . . . . . . . . . . . . . . . . 106 6.8.2. Overload Bit
6.8.2. Overload Bit . . . . . . . . . . . . . . . . . . . . 107 6.8.3. Optimized Route Computation on Leaves
6.8.3. Optimized Route Computation on Leaves . . . . . . . . 107 6.8.4. Mobility
6.8.4. Mobility . . . . . . . . . . . . . . . . . . . . . . 108 6.8.5. Key/Value (KV) Store
6.8.5. Key/Value (KV) Store . . . . . . . . . . . . . . . . 111 6.8.6. Interactions with BFD
6.8.6. Interactions with BFD . . . . . . . . . . . . . . . . 112 6.8.7. Fabric Bandwidth Balancing
6.8.7. Fabric Bandwidth Balancing . . . . . . . . . . . . . 113 6.8.8. Label Binding
6.8.8. Label Binding . . . . . . . . . . . . . . . . . . . . 116 6.8.9. Leaf-to-Leaf Procedures
6.8.9. Leaf to Leaf Procedures . . . . . . . . . . . . . . . 116 6.8.10. Address Family and Multi-Topology Considerations
6.8.10. Address Family and Multi Topology Considerations . . 117 6.8.11. One-Hop Healing of Levels with East-West Links
6.8.11. One-Hop Healing of Levels with East-West Links . . . 117 6.9. Security
6.9. Security . . . . . . . . . . . . . . . . . . . . . . . . 117 6.9.1. Security Model
6.9.1. Security Model . . . . . . . . . . . . . . . . . . . 117 6.9.2. Security Mechanisms
6.9.2. Security Mechanisms . . . . . . . . . . . . . . . . . 119 6.9.3. Security Envelope
6.9.3. Security Envelope . . . . . . . . . . . . . . . . . . 120 6.9.4. Weak Nonces
6.9.4. Weak Nonces . . . . . . . . . . . . . . . . . . . . . 124 6.9.5. Lifetime
6.9.5. Lifetime . . . . . . . . . . . . . . . . . . . . . . 125 6.9.6. Security Association Changes
6.9.6. Security Association Changes . . . . . . . . . . . . 125 7. Information Elements Schema
7. Information Elements Schema . . . . . . . . . . . . . . . . . 125 7.1. Backwards-Compatible Extension of Schema
7.1. Backwards-Compatible Extension of Schema . . . . . . . . 126 7.2. common.thrift
7.2. common.thrift . . . . . . . . . . . . . . . . . . . . . . 127 7.3. encoding.thrift
7.3. encoding.thrift . . . . . . . . . . . . . . . . . . . . . 133 8. Further Details on Implementation
8. Further Details on Implementation . . . . . . . . . . . . . . 140 8.1. Considerations for Leaf-Only Implementation
8.1. Considerations for Leaf-Only Implementation . . . . . . . 140 8.2. Considerations for Spine Implementation
8.2. Considerations for Spine Implementation . . . . . . . . . 141 9. Security Considerations
9. Security Considerations . . . . . . . . . . . . . . . . . . . 141 9.1. General
9.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 141 9.2. Time to Live and Hop Limit Values
9.2. Time to Live and Hop Limit Values . . . . . . . . . . . . 142 9.3. Malformed Packets
9.3. Malformed Packets . . . . . . . . . . . . . . . . . . . . 142 9.4. RIFT ZTP
9.4. RIFT ZTP . . . . . . . . . . . . . . . . . . . . . . . . 143 9.5. Lifetime
9.5. Lifetime . . . . . . . . . . . . . . . . . . . . . . . . 143 9.6. Packet Number
9.6. Packet Number . . . . . . . . . . . . . . . . . . . . . . 143 9.7. Outer Fingerprint Attacks
9.7. Outer Fingerprint Attacks . . . . . . . . . . . . . . . . 143 9.8. TIE Origin Fingerprint DoS Attacks
9.8. TIE Origin Fingerprint DoS Attacks . . . . . . . . . . . 144 9.9. Host Implementations
9.9. Host Implementations . . . . . . . . . . . . . . . . . . 144 9.9.1. IPv4 Broadcast and IPv6 All-Routers Multicast
9.9.1. IPv4 Broadcast and IPv6 All Routers Multicast Implementations
Implementations . . . . . . . . . . . . . . . . . . . 145 10. IANA Considerations
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 145 10.1. Multicast and Port Numbers
10.1. Requested Multicast and Port Numbers . . . . . . . . . . 145 10.2. Registry for RIFT Security Algorithms
10.2. Requested Registry for RIFT Security Algorithms . . . . 146 10.3. Registries with Assigned Values for Schema Values
10.3. Requested Registries with Assigned Values for Schema 10.3.1. RIFTVersions Registry
Values . . . . . . . . . . . . . . . . . . . . . . . . . 147 10.3.2. RIFTCommonAddressFamilyType Registry
10.3.1. Registry RIFT/Versions . . . . . . . . . . . . . . . 148 10.3.3. RIFTCommonHierarchyIndications Registry
10.3.2. Registry RIFT/common/AddressFamilyType . . . . . . . 148 10.3.4. RIFTCommonIEEE8021ASTimeStampType Registry
10.3.3. Registry RIFT/common/HierarchyIndications . . . . . 149 10.3.5. RIFTCommonIPAddressType Registry
10.3.4. Registry RIFT/common/IEEE802_1ASTimeStampType . . . 149 10.3.6. RIFTCommonIPPrefixType Registry
10.3.5. Registry RIFT/common/IPAddressType . . . . . . . . . 150 10.3.7. RIFTCommonIPv4PrefixType Registry
10.3.6. Registry RIFT/common/IPPrefixType . . . . . . . . . 150 10.3.8. RIFTCommonIPv6PrefixType Registry
10.3.7. Registry RIFT/common/IPv4PrefixType . . . . . . . . 151 10.3.9. RIFTCommonKVTypes Registry
10.3.8. Registry RIFT/common/IPv6PrefixType . . . . . . . . 151 10.3.10. RIFTCommonPrefixSequenceType Registry
10.3.9. Registry RIFT/common/KVTypes . . . . . . . . . . . . 152 10.3.11. RIFTCommonRouteType Registry
10.3.10. Registry RIFT/common/PrefixSequenceType . . . . . . 152 10.3.12. RIFTCommonTIETypeType Registry
10.3.11. Registry RIFT/common/RouteType . . . . . . . . . . . 153 10.3.13. RIFTCommonTieDirectionType Registry
10.3.12. Registry RIFT/common/TIETypeType . . . . . . . . . . 154 10.3.14. RIFTEncodingCommunity Registry
10.3.13. Registry RIFT/common/TieDirectionType . . . . . . . 155 10.3.15. RIFTEncodingKeyValueTIEElement Registry
10.3.14. Registry RIFT/encoding/Community . . . . . . . . . . 156 10.3.16. RIFTEncodingKeyValueTIEElementContent Registry
10.3.15. Registry RIFT/encoding/KeyValueTIEElement . . . . . 156 10.3.17. RIFTEncodingLIEPacket Registry
10.3.16. Registry RIFT/encoding/KeyValueTIEElementContent . . 157 10.3.18. RIFTEncodingLinkCapabilities Registry
10.3.17. Registry RIFT/encoding/LIEPacket . . . . . . . . . . 157 10.3.19. RIFTEncodingLinkIDPair Registry
10.3.18. Registry RIFT/encoding/LinkCapabilities . . . . . . 160 10.3.20. RIFTEncodingNeighbor Registry
10.3.19. Registry RIFT/encoding/LinkIDPair . . . . . . . . . 161 10.3.21. RIFTEncodingNodeCapabilities Registry
10.3.20. Registry RIFT/encoding/Neighbor . . . . . . . . . . 163 10.3.22. RIFTEncodingNodeFlags Registry
10.3.21. Registry RIFT/encoding/NodeCapabilities . . . . . . 163 10.3.23. RIFTEncodingNodeNeighborsTIEElement Registry
10.3.22. Registry RIFT/encoding/NodeFlags . . . . . . . . . . 164 10.3.24. RIFTEncodingNodeTIEElement Registry
10.3.23. Registry RIFT/encoding/NodeNeighborsTIEElement . . . 165 10.3.25. RIFTEncodingPacketContent Registry
10.3.24. Registry RIFT/encoding/NodeTIEElement . . . . . . . 166 10.3.26. RIFTEncodingPacketHeader Registry
10.3.25. Registry RIFT/encoding/PacketContent . . . . . . . . 167 10.3.27. RIFTEncodingPrefixAttributes Registry
10.3.26. Registry RIFT/encoding/PacketHeader . . . . . . . . 168 10.3.28. RIFTEncodingPrefixTIEElement Registry
10.3.27. Registry RIFT/encoding/PrefixAttributes . . . . . . 169 10.3.29. RIFTEncodingProtocolPacket Registry
10.3.28. Registry RIFT/encoding/PrefixTIEElement . . . . . . 171 10.3.30. RIFTEncodingTIDEPacket Registry
10.3.29. Registry RIFT/encoding/ProtocolPacket . . . . . . . 171 10.3.31. RIFTEncodingTIEElement Registry
10.3.30. Registry RIFT/encoding/TIDEPacket . . . . . . . . . 171 10.3.32. RIFTEncodingTIEHeader Registry
10.3.31. Registry RIFT/encoding/TIEElement . . . . . . . . . 172 10.3.33. RIFTEncodingTIEHeaderWithLifeTime Registry
10.3.32. Registry RIFT/encoding/TIEHeader . . . . . . . . . . 173 10.3.34. RIFTEncodingTIEID Registry
10.3.33. Registry RIFT/encoding/TIEHeaderWithLifeTime . . . . 174 10.3.35. RIFTEncodingTIEPacket Registry
10.3.34. Registry RIFT/encoding/TIEID . . . . . . . . . . . . 175 10.3.36. RIFTEncodingTIREPacket Registry
10.3.35. Registry RIFT/encoding/TIEPacket . . . . . . . . . . 175 11. References
10.3.36. Registry RIFT/encoding/TIREPacket . . . . . . . . . 176 11.1. Normative References
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 176 11.2. Informative References
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 177 Appendix A. Sequence Number Binary Arithmetic
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 178 Appendix B. Examples
13.1. Normative References . . . . . . . . . . . . . . . . . . 178 B.1. Normal Operation
13.2. Informative References . . . . . . . . . . . . . . . . . 180 B.2. Leaf Link Failure
Appendix A. Sequence Number Binary Arithmetic . . . . . . . . . 183 B.3. Partitioned Fabric
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 184 B.4. Northbound Partitioned Router and Optional East-West Links
B.1. Normal Operation . . . . . . . . . . . . . . . . . . . . 184 Acknowledgments
B.2. Leaf Link Failure . . . . . . . . . . . . . . . . . . . . 186 Contributors
B.3. Partitioned Fabric . . . . . . . . . . . . . . . . . . . 187 Authors' Addresses
B.4. Northbound Partitioned Router and Optional East-West
Links . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 189
1. Introduction 1. Introduction
Clos [CLOS] topologies have gained prominence in today's networking, Clos [CLOS] topologies have gained prominence in today's networking,
primarily as a result of the paradigm shift towards a centralized primarily as a result of the paradigm shift towards a centralized
data-center architecture that is poised to deliver a majority of data center architecture that is poised to deliver a majority of
computation and storage services in the future. Such networks are computation and storage services in the future. Such networks are
called commonly a fat tree/network in modern IP fabric considerations commonly called a Fat Tree / network in modern IP fabric
[VAHDAT08] as homonym to the original definition of the term considerations [VAHDAT08] as a homonym to the original definition of
[FATTREE]. In most generic terms, and disregarding exceptions like the term [FATTREE]. In most generic terms, and disregarding
horizontal shortcuts, those networks are all variations of a exceptions like horizontal shortcuts, those networks are all
structured design isomorphic to a ranked lattice where the least variations of a structured design isomorphic to a ranked lattice
upper bound is the "top of the fabric" and links closer to the top where the least upper bound is the "top of the fabric" and links
may be "fatter" to guarantee non-blocking bi-sectional capacity. closer to the top may be "fatter" to guarantee non-blocking
bisectional capacity.
Many builders of such IP fabrics desire a protocol that auto- Many builders of such IP fabrics desire a protocol that
configures itself and deals with failures and mis-configurations with autoconfigures itself and deals with failures and misconfigurations
a minimum of human intervention. Such a solution would allow local with a minimum amount of human intervention. Such a solution would
IP fabric bandwidth to be consumed in a 'standard component' fashion, allow local IP fabric bandwidth to be consumed in a "standard
i.e. provision it much faster and operate it at much lower costs than component" fashion, i.e., provision it much faster and operate it at
today, much like compute or storage is consumed already. much lower costs than today, much like compute or storage is consumed
already.
In looking at the problem through the lens of such IP fabric In looking at the problem through the lens of such IP fabric
requirements, RIFT (Routing in Fat Trees) addresses those challenges requirements, Routing in Fat Trees (RIFT) addresses those challenges
not through an incremental modification of either a link-state not through an incremental modification of either a link-state
(distributed computation) or distance-vector (diffused computation) (distributed computation) or distance-vector (diffused computation)
techniques but rather a mixture of both, briefly described as "link- technique but rather a mixture of both, briefly described as "link-
state towards the spines" and "distance vector towards the leaves". state towards the spines" and "distance vector towards the leaves".
In other words, "bottom" levels are flooding their link-state In other words, "bottom" levels are flooding their link-state
information in the "northern" direction while each node generates information in the "northern" direction while each node generates
under normal conditions a "default route" and floods it in the under normal conditions a "default route" and floods it in the
"southern" direction. This type of protocol naturally supports "southern" direction. This type of protocol naturally supports
highly desirable address aggregation. Alas, such aggregation could highly desirable address aggregation. Alas, such aggregation could
drop traffic in cases of misconfiguration or while failures are being drop traffic in cases of misconfiguration or while failures are being
resolved or even cause persistent network partitioning and this has resolved or even cause persistent network partitioning and this has
to be addressed by some adequate mechanism. The approach RIFT takes to be addressed by some adequate mechanism. The approach RIFT takes
is described in Section 6.5 and is based on automatic, sufficient is described in Section 6.5 and is based on automatic, sufficient
disaggregation of prefixes in case of link and node failures. disaggregation of prefixes in case of link and node failures.
The protocol further provides: The protocol further provides:
* optional fully automated construction of fat tree topologies based * optional fully automated construction of Fat Tree topologies based
on detection of links without any configuration (Section 6.7), on detection of links without any configuration (Section 6.7)
while allowing for conventional configuration methods or an while allowing for conventional configuration methods or an
arbitrary mix of both, arbitrary mix of both,
* minimum amount of routing state held by nodes, * the minimum amount of routing state held by nodes,
* automatic pruning and load balancing of topology flooding * automatic pruning and load balancing of topology flooding
exchanges over a sufficient subset of links (Section 6.3.9), exchanges over a sufficient subset of links (Section 6.3.9),
* automatic address aggregation (Section 6.3.8) and consequently * automatic address aggregation (Section 6.3.8) and consequently
automatic disaggregation (Section 6.5) of prefixes on link and automatic disaggregation (Section 6.5) of prefixes on link and
node failures to prevent traffic loss and suboptimal routing, node failures to prevent traffic loss and suboptimal routing,
* loop-free non-ECMP forwarding due to its inherent valley-free * loop-free non-ECMP forwarding due to its inherent valley-free
nature, nature,
* fast mobility (Section 6.8.4), * fast mobility (Section 6.8.4),
* re-balancing of traffic towards the spines based on bandwidth * rebalancing of traffic towards the spines based on bandwidth
available (Section 6.8.7.1), and finally available (Section 6.8.7.1), and finally
* mechanisms to synchronize a limited key-value data-store * mechanisms to synchronize a limited key-value datastore
(Section 6.8.5.1) that can be used after protocol convergence to (Section 6.8.5.1) that can be used after protocol convergence to,
e.g. bootstrap higher levels of functionality on nodes. e.g., bootstrap higher levels of functionality on nodes.
Figure 1 illustrates a simplified, conceptual view of a RIFT fabric Figure 1 illustrates a simplified, conceptual view of a RIFT fabric
with its routing tables and topology databases using IPv4 as address with its routing tables and topology databases using IPv4 as the
family. The top of the fabric's link-state database holds address family. The top of the fabric's link-state database holds
information about the nodes below it and the routes to them. When information about the nodes below it and the routes to them. When
referring to Figure 1, /32 notation corresponds to each node's IPv4 referring to Figure 1, /32 notation corresponds to each node's IPv4
loopback address (e.g. A/32 is node A's loopback, etc.) and 0/0 loopback address (e.g., A/32 is node A's loopback, etc.) and 0/0
indicates a default IPv4 route. The first row of database indicates a default IPv4 route. The first row of database
information represents the nodes for which full topology information information represents the nodes for which full topology information
is available. The second row of database information indicates that is available. The second row of database information indicates that
partial information of other nodes in the same level is also partial information of other nodes in the same level is also
available. Such information will be needed to perform certain available. Such information will be needed to perform certain
algorithms necessary for correct protocol operation. When the algorithms necessary for correct protocol operation. When the
"bottom" (or in other words leaves) of the fabric is considered, the "bottom" (or in other words leaves) of the fabric is considered, the
topology is basically empty and, under normal conditions, the leaves topology is basically empty and, under normal conditions, the leaves
hold a load balanced default route to the next level. hold a load-balanced default route to the next level.
The remainder of this document fills in the protocol specification The remainder of this document fills in the protocol specification
details. details.
[A,B,C,D] [A,B,C,D]
[E] [E]
+---------+ +---------+ A/32 @ [C,D] +---------+ +---------+ A/32 @ [C,D]
| E | | F | B/32 @ [C,D] | E | | F | B/32 @ [C,D]
+-+-----+-+ +-+-----+-+ C/32 @ C +-+-----+-+ +-+-----+-+ C/32 @ C
skipping to change at page 8, line 9 skipping to change at line 319
+-+-----+-+ +-+-----+-+ +-+-----+-+ +-+-----+-+
0/0 @ [C,D] | A | | B | 0/0 @ [C,D] 0/0 @ [C,D] | A | | B | 0/0 @ [C,D]
+---------+ +---------+ +---------+ +---------+
Figure 1: RIFT Information Distribution Figure 1: RIFT Information Distribution
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. A Reader's Digest 2. A Reader's Digest
This section is an initial guided tour through the document in order This section is an initial guided tour through the document in order
to convey the necessary information for different readers, depending to convey the necessary information for different readers, depending
on their level of interest. The authors recommend reading the HTML on their level of interest. The authors recommend reading the HTML
or PDF versions of this document due to the inherent limitation of or PDF versions of this document due to the inherent limitation of
text version to represent complex figures. text version to represent complex figures.
The Terminology (Section 3.1) section should be used as a supporting The "Terminology" (Section 3.1) section should be used as a
reference as the document is read. supporting reference as the document is read.
The indications of direction (i.e. "top", "bottom", etc.) referenced The indications of direction (i.e., "top", "bottom", etc.) referenced
in Section 1 are of paramount importance. RIFT requires a topology in Section 1 are of paramount importance. RIFT requires a topology
with a sense of top and bottom in order to properly achieve a sorted with a sense of top and bottom in order to properly achieve a sorted
topology. Clos, Fat Tree, and other similarly structured networks topology. Clos, Fat Tree, and other similarly structured networks
are conducive to such requirements. Where RIFT does allow for are conducive to such requirements. Where RIFT allows for further
further relaxation of these constraints, this will be mentioned later relaxation of these constraints will be mentioned later in this
in this section. section.
Several of the images in this document are annotated with "northern Several of the images in this document are annotated with "northern
view" or "southern view" to indicate perspective to the reader. A view" or "southern view" to indicate perspective to the reader. A
"northern view" should be interpreted as "from the top of the fabric "northern view" should be interpreted as "from the top of the fabric
looking down", whereas "southern view" should be interpreted as "from looking down", whereas "southern view" should be interpreted as "from
the bottom looking up". the bottom looking up".
Operators and implementors alike must decide whether multi-plane IP Operators and implementors alike must decide whether multi-plane IP
fabrics are of interest for them. Section 3.2 illustrates an example fabrics are of interest for them. Section 3.2 illustrates an example
of both single-plane in Figure 2 and multi-plane fabric in Figure 3. of both single-plane in Figure 2 and multi-plane fabric in Figure 3.
Multi-plane fabrics require understanding of additional RIFT concepts Multi-plane fabrics require understanding of additional RIFT concepts
(e.g. negative disaggregation in Section 6.5.2) that are unnecessary (e.g., negative disaggregation in Section 6.5.2) that are unnecessary
in the context of fabrics consisting of a single-plane only. The in the context of fabrics consisting of a single-plane only.
Overview (Section 5) and Section 5.2 aim to provide enough context to "Overview" (Section 5) and "Generalized Topology View" (Section 5.2)
determine if multi-plane fabrics are of interest to the reader. The aim to provide enough context to determine if multi-plane fabrics are
Fallen Leaf part (Section 5.3), and additionally Section 5.4 and of interest to the reader. "Fallen Leaf Problem" (Section 5.3) and
Section 5.5 describe further considerations that are specific to additionally Sections 5.4 and 5.5 describe further considerations
multi-plane fabrics. that are specific to multi-plane fabrics.
The fundamental protocol concepts are described starting in the The fundamental protocol concepts are described starting in
specification part (Section 6), but some sub-sections are less "Specification" (Section 6), but some subsections are less relevant
relevant unless the protocol is being implemented. The protocol unless the protocol is being implemented. The protocol transport
transport (Section 6.1) is of particular importance for two reasons. (Section 6.1) is of particular importance for two reasons. First, it
First, it introduces RIFT's packet format content in the form of a introduces RIFT's packet format content in the form of a normative
normative Thrift [thrift] model given in Section 7.3 which is carried Thrift [thrift] model given in Section 7.3, which is carried in an
in according security envelope as described in Section 6.9.3. according security envelope as described in Section 6.9.3. Second,
Second, the Thrift model component is a prerequisite to understanding the Thrift model component is a prerequisite to understanding the
the RIFT's inherent security features as defined in both security RIFT's inherent security features as defined in both "Security"
models part (Section 6.9) and the security segment (Section 9). The (Section 6.9) and "Security Considerations" (Section 9). The
normative schema defining the Thrift model can be found in normative schema defining the Thrift model can be found in Sections
Section 7.2 and Section 7.3. Furthermore, while a detailed 7.2 and 7.3. Furthermore, while a detailed understanding of Thrift
understanding of Thrift [thrift] and the models is not required [thrift] and the model is not required unless implementing RIFT, they
unless implementing RIFT, they may provide additional useful may provide additional useful information for other readers.
information for other readers.
If implementing RIFT to support multi-plane topologies Section 6 If implementing RIFT to support multi-plane topologies, Section 6
should be reviewed in its entirety in conjunction with the previously should be reviewed in its entirety in conjunction with the previously
mentioned Thrift schemas. Sections not relevant to single-plane mentioned Thrift schemas. Sections not relevant to single-plane
implementations will be noted later in this section. implementations will be noted later in this section.
All readers dealing with implementation of the protocol should pay All readers dealing with implementation of the protocol should pay
special attention to the Link Information Element (LIE) definitions special attention to the Link Information Element (LIE) definitions
part (Section 6.2) as it not only outlines basic neighbor discovery (Section 6.2) as it not only outlines basic neighbor discovery and
and adjacency formation, but also provides necessary context for adjacency formation but also provides necessary context for RIFT's
RIFT's optional Zero Touch Provisioning (ZTP) (Section 6.7) and mis- optional Zero Touch Provisioning (ZTP) (Section 6.7) and miscabling
cabling detection capabilities that allow it to automatically detect detection capabilities that allow it to automatically detect and
and build the underlay topology with basically no configuration. build the underlay topology with basically no configuration. These
These specific capabilities are detailed in Section 6.7. specific capabilities are detailed in Section 6.7.
For other readers, the following sections provide a more detailed For other readers, the following sections provide a more detailed
understanding of the fundamental properties and highlight some understanding of the fundamental properties and highlight some
additional benefits of RIFT such as link state packet formats, additional benefits of RIFT, such as link-state packet formats,
efficient flooding, synchronization, loop-free path computation and efficient flooding, synchronization, loop-free path computation, and
link-state database maintenance - Section 6.3, Section 6.3.2, link-state database maintenance (see Sections 6.3, 6.3.2, 6.3.3,
Section 6.3.3, Section 6.3.4, Section 6.3.6, Section 6.3.7, 6.3.4, 6.3.6, 6.3.7, 6.3.8, 6.4, 6.4.1, 6.4.2, 6.4.3, and 6.4.4).
Section 6.3.8, Section 6.4, Section 6.4.1, Section 6.4.2, RIFT's ability to perform weighted unequal-cost load balancing of
Section 6.4.3, Section 6.4.4. RIFT's ability to perform weighted traffic across all available links is outlined in Section 6.8.7 with
unequal-cost load balancing of traffic across all available links is an accompanying example.
outlined in Section 6.8.7 with an accompanying example.
Section 6.5 is the place where the single-plane vs. multi-plane Section 6.5 is the place where the single-plane vs. multi-plane
requirement is explained in more detail. For those interested in requirement is explained in more detail. For those interested in
single-plane fabrics, only Section 6.5.1 is required. For the multi- single-plane fabrics, only Section 6.5.1 is required. For the multi-
plane interested reader Section 6.5.2, Section 6.5.2.1, plane-interested reader, Sections 6.5.2, 6.5.2.1, 6.5.2.2, and
Section 6.5.2.2, and Section 6.5.2.3 are also mandatory. Section 6.6 6.5.2.3 are also mandatory. Section 6.6 is especially important for
is especially important for any multi-plane interested reader as it any multi-plane-interested reader as it outlines how the Routing
outlines how the RIB (Routing Information Base) and FIB (Forwarding Information Base (RIB) and Forwarding Information Base (FIB) are
Information Base) are built via the disaggregation mechanisms, but built via the disaggregation mechanisms but also illustrates how they
also illustrates how they prevent defective routing decisions that prevent defective routing decisions that cause traffic loss in both
cause traffic loss in both single or multi-plane topologies. single-plane or multi-plane topologies.
Appendix B contains a set of comprehensive examples that show how Appendix B contains a set of comprehensive examples that show how
RIFT contains the impact of failures to only the required set of RIFT contains the impact of failures to only the required set of
nodes. It should also help cement some of RIFT's core concepts in nodes. It should also help cement some of RIFT's core concepts in
the reader's mind. the reader's mind.
Last, but not least, RIFT has other optional capabilities. One Last but not least, RIFT has other optional capabilities. One
example is the key-value data-store, which enables RIFT to advertise example is the key-value datastore, which enables RIFT to advertise
data post-convergence in order to bootstrap higher levels of data post-convergence in order to bootstrap higher levels of
functionality (e.g. operational telemetry). Those are covered in functionality (e.g., operational telemetry). Those are covered in
Section 6.8. Section 6.8.
More information related to RIFT can be found in the "RIFT More information related to RIFT can be found in the "RIFT
Applicability" [APPLICABILITY] document, which discusses alternate Applicability" [APPLICABILITY] document, which discusses alternate
topologies upon which RIFT may be deployed, use cases where it is topologies upon which RIFT may be deployed, describes use cases where
applicable, and presents operational considerations that complement it is applicable, and presents operational considerations that
this document. The RIFT DayOne [DayOne] book covers some practical complement this document. "RIFT Day One" [DayOne] covers some
details of existing RIFT implementations and deployment details. practical details of existing RIFT implementations and deployment
details.
3. Reference Frame 3. Reference Frame
3.1. Terminology 3.1. Terminology
This section presents the terminology used in this document. This section presents the terminology used in this document.
Bandwidth Adjusted Distance (BAD): Bandwidth Adjusted Distance (BAD):
Each RIFT node can calculate the amount of northbound bandwidth Each RIFT node can calculate the amount of northbound bandwidth
available towards a node compared to other nodes at the same level available towards a node compared to other nodes at the same level
and can modify the route distance accordingly to allow for the and can modify the route distance accordingly to allow for the
lower level to adjust their load balancing towards spines. lower level to adjust their load balancing towards spines.
Bi-directional Adjacency: Bidirectional Adjacency:
Bidirectional adjacency is an adjacency where nodes of both sides Bidirectional adjacency is an adjacency where nodes of both sides
of the adjacency advertised it in the Node TIEs with the correct of the adjacency advertised it in the Node TIEs with the correct
levels and System IDs. Bi-directionality is used to check in levels and System IDs. Bidirectionality is used to check in
different algorithms whether the link should be included. different algorithms whether the link should be included.
Bow-tying: Bow-tying:
Traffic patterns in fully converged IP fabrics traverse normally Traffic patterns in fully converged IP fabrics normally traverse
the shortest route based on hop count toward their destination the shortest route based on hop count towards their destination
(e.g., leaf, spine, leaf). Some failure scenarios with partial (e.g., leaf, spine, leaf). Some failure scenarios with partial
routing information cause nodes to lose the required downstream routing information cause nodes to lose the required downstream
reachability to a destination and force traffic to utilize routes reachability to a destination and force traffic to utilize routes
that traverse higher levels in the fabric in order to turn south that traverse higher levels in the fabric in order to turn south
again using a different route to resolve reachability (e.g., leaf, again using a different route to resolve reachability (e.g., leaf,
spine-1, super-spine, spine-2, leaf). spine-1, super-spine, spine-2, leaf).
Clos/Fat Tree: Clos / Fat Tree:
This document uses the terms Clos and Fat Tree interchangeably This document uses the terms "Clos" and "Fat Tree" interchangeably
where it always refers to a folded spine-and-leaf topology with where it always refers to a folded spine-and-leaf topology with
possibly multiple Points of Delivery (PoDs) and one or multiple possibly multiple Points of Delivery (PoDs) and one or multiple
Top of Fabric (ToF) planes. Several modifications such as leaf- Top of Fabric (ToF) planes. Several modifications such as leaf-
2-leaf shortcuts and multiple level shortcuts are possible and to-leaf shortcuts and shortcuts that span multiple levels are
described further in the document. possible and described further in the document.
Cost: Cost:
A natural number without a unit associated with two entities. The A natural number without a unit associated with two entities. The
usual natural numbers algebra can be applied to costs. A cost may usual natural numbers algebra can be applied to costs. A cost may
be associated with either a single link or prefix or it may be associated with either a single link or prefix, or it may
represent the sum of costs (distance) of links in the path between represent the sum of costs (distance) of links in the path between
two nodes. two nodes.
Crossbar: Crossbar:
Physical arrangement of ports in a switching matrix without Physical arrangement of ports in a switching matrix without
implying any further scheduling or buffering disciplines. implying any further scheduling or buffering disciplines.
Directed Acyclic Graph (DAG): Directed Acyclic Graph (DAG):
A finite directed graph with no directed cycles (loops). If links A finite directed graph with no directed cycles (loops). If links
in a Clos are considered as either being all directed towards the in a Clos are considered as either being all directed towards the
top or vice versa, each of such two graphs is a DAG. top or vice versa, each of two such graphs is a DAG.
Disaggregation: Disaggregation:
Process in which a node decides to advertise more specific The process in which a node decides to advertise more specific
prefixes Southwards, either positively to attract the prefixes southwards, either positively to attract the
corresponding traffic, or negatively to repel it. Disaggregation corresponding traffic or negatively to repel it. Disaggregation
is performed to prevent traffic loss and suboptimal routing to the is performed to prevent traffic loss and suboptimal routing to the
more specific prefixes. more specific prefixes.
Distance: Distance:
The sum of costs (bound by infinite cost constant) between two The sum of costs (bound by the infinite cost constant) between two
nodes. A distance is primarily used to express separation between nodes. A distance is primarily used to express separation between
two entities and can be used again as cost in another context. two entities and can be used again as cost in another context.
East-West (E-W) Link: East-West (E-W) Link:
A link between two nodes at the same level. East-West links are A link between two nodes at the same level. East-West links are
normally not part of Clos or "fat tree" topologies. normally not part of Clos or Fat Tree topologies.
Flood Repeater (FR): Flood Repeater (FR):
A node can designate one or more northbound neighbor nodes to be A node can designate one or more northbound neighbor nodes to be
flood repeaters. The flood repeaters are responsible for flooding flood repeaters. The flood repeaters are responsible for flooding
northbound TIEs further north. The document sometimes calls them northbound TIEs further north. The document sometimes calls them
flood leaders as well. flood leaders as well.
Folded Spine-and-Leaf: Folded Spine-and-Leaf:
In case the Clos fabric input and output stages are equivalent, In case the Clos fabric input and output stages are equivalent,
the fabric can be "folded" to build a "superspine" or top which is the fabric can be "folded" to build a "superspine" or top, which
called the ToF in this document. is called the ToF in this document.
Interface: Interface:
A layer 3 entity over which RIFT control packets are exchanged. A layer 3 entity over which RIFT control packets are exchanged.
Key Value (KV) TIE: Key Value (KV) TIE:
A TIE that is carrying a set of key value pairs [DYNAMO]. It can A TIE that is carrying a set of key value pairs [DYNAMO]. It can
be used to distribute non topology related information within the be used to distribute non-topology-related information within the
protocol. protocol.
Leaf-to-Leaf Shortcuts (L2L): Leaf-to-Leaf (L2L) Shortcuts:
East-West links at leaf level will need to be differentiated from East-West links at leaf level will need to be differentiated from
East-West links at other levels. East-West links at other levels.
Leaf: Leaf:
A node without southbound adjacencies. Level 0 implies a leaf in A node without southbound adjacencies. Level 0 implies a leaf in
RIFT but a leaf does not have to be level 0. RIFT, but a leaf does not have to be level 0.
Level: Level:
Clos and Fat Tree networks are topologically partially ordered Clos and Fat Tree networks are topologically partially ordered
graphs and 'level' denotes the set of nodes at the same height in graphs, and "level" denotes the set of nodes at the same height in
such a network. Nodes at the top level (i.e., ToF) are at the such a network. Nodes at the top level (i.e., ToF) are at the
level with the highest value and count down to the nodes at the level with the highest value and count down to the nodes at the
bottom level (i.e., leaf) with the lowest value. A node will have bottom level (i.e., leaf) with the lowest value. A node will have
links to nodes one level down and/or one level up. In some links to nodes one level down and/or one level up. In some
circumstances, a node may have links to other nodes at the same circumstances, a node may have links to other nodes at the same
level. A leaf node may also have links to nodes multiple levels level. A leaf node may also have links to nodes multiple levels
higher. In RIFT, Level 0 always indicates that a node is a leaf, higher. In RIFT, level 0 always indicates that a node is a leaf
but does not have to be level 0. Level values can be configured but does not have to be level 0. Level values can be configured
manually or automatically derived via Section 6.7. As a final manually or automatically as described in Section 6.7. As a final
footnote: Clos terminology often uses the concept of "stage", but footnote: Clos terminology often uses the concept of "stage", but
due to the folded nature of the Fat Tree it is not used from this due to the folded nature of the Fat Tree, it is not used from this
point on to prevent misunderstandings. point on to prevent misunderstandings.
LIE: LIE:
This is an acronym for a "Link Information Element" exchanged on This is an acronym for a "Link Information Element" exchanged on
all the system's links running RIFT to form _ThreeWay_ adjacencies all the system's links running RIFT to form _ThreeWay_ adjacencies
and carry information used to perform RIFT Zero Touch Provisioning and carry information used to perform RIFT Zero Touch Provisioning
(ZTP) of levels. (ZTP) of levels.
Metric: Metric:
Used interchangeably with cost. Used interchangeably with "cost".
Neighbor: Neighbor:
Once a _ThreeWay_ adjacency has been formed a neighborship Once a _ThreeWay_ adjacency has been formed, a neighborship
relationship contains the neighbor's properties. Multiple relationship contains the neighbor's properties. Multiple
adjacencies can be formed to a remote node via parallel point-to- adjacencies can be formed to a remote node via parallel point-to-
point interfaces but such adjacencies are *not* sharing a neighbor point interfaces, but such adjacencies are *not* sharing a
structure. Saying "neighbor" is thus equivalent to saying "a neighbor structure. Saying "neighbor" is thus equivalent to
_ThreeWay_ adjacency". saying "a _ThreeWay_ adjacency".
Node TIE: Node TIE:
This stands as acronym for a "Node Topology Information Element", This is an acronym for a "Node Topology Information Element",
which contains all adjacencies the node discovered and information which contains all adjacencies the node discovered and information
about the node itself. Node TIE should not be confused with a about the node itself. Node TIE should not be confused with a
North TIE since "node" defines the type of TIE rather than its North TIE since "node" defines the type of TIE rather than its
direction. Consequently, North Node TIEs and South Node TIEs direction. Consequently, North Node TIEs and South Node TIEs
exist. exist.
North SPF (N-SPF): North SPF (N-SPF):
A reachability calculation that is progressing northbound, as A reachability calculation that is progressing northbound, for
example SPF that is using South Node TIEs only. Normally it example, SPF that is using South Node TIEs only. Normally it
progresses a single hop only and installs default routes. progresses by only a single hop and installs default routes.
Northbound Link: Northbound Link:
A link to a node one level up or in other words, one level further A link to a node one level up or, in other words, one level
north. further north.
Northbound representation: Northbound Representation:
Subset of topology information flooded towards higher levels of The subset of topology information flooded towards higher levels
the fabric. of the fabric.
Overloaded: Overloaded:
Applies to a node advertising the _overload_ attribute as set. Applies to a node advertising the _overload_ attribute as set.
Overload attribute is carried in the _NodeFlags_ object of the The overload attribute is carried in the _NodeFlags_ object of the
encoding schema. encoding schema.
Point of Delivery (PoD): Point of Delivery (PoD):
A self-contained vertical slice or subset of a Clos or Fat Tree A self-contained vertical slice or subset of a Clos or Fat Tree
network containing normally only level 0 and level 1 nodes. A network normally containing only level 0 and level 1 nodes. A
node in a PoD communicates with nodes in other PoDs via the ToF node in a PoD communicates with nodes in other PoDs via the ToF
nodes. PoDs are numbered to distinguish them and PoD value 0 nodes. PoDs are numbered to distinguish them, and PoD value 0
(defined later in the encoding schema as _common.default_pod_) is (defined later in the encoding schema as _common.default_pod_) is
used to denote "undefined" or "any" PoD. used to denote "undefined" or "any" PoD.
Prefix TIE: Prefix TIE:
This is an acronym for a "Prefix Topology Information Element" and This is an acronym for a "Prefix Topology Information Element",
it contains all prefixes directly attached to this node in case of and it contains all prefixes directly attached to this node in
a North TIE and in case of South TIE the necessary default routes case of a North TIE and the necessary default routes the node
the node advertises southbound. advertises southbound in case of a South TIE.
Radix: Radix:
A radix of a switch is the number of switching ports it provides. A radix of a switch is the number of switching ports it provides.
It's sometimes called fanout as well. It's sometimes called "fanout" as well.
Routing on the Host (RotH): Routing on the Host (RotH):
Modern data center architecture variant where servers/leaves are A modern data center architecture variant where servers/leaves are
multi-homed and consequently participate in routing. multihomed and consequently participate in routing.
Security Envelope: Security Envelope:
RIFT packets are flooded within an authenticated security envelope RIFT packets are flooded within an authenticated security envelope
that allows to protect the integrity of information a node accepts that allows to protect the integrity of information a node accepts
if any of the mechanisms in Section 10.2 is used. This is further if any of the mechanisms in Section 10.2 are used. This is
described in Section 6.9.3. further described in Section 6.9.3.
Shortest-Path First (SPF): Shortest Path First (SPF):
A well-known graph algorithm attributed to Dijkstra [DIJKSTRA] A well-known graph algorithm attributed to Dijkstra [DIJKSTRA]
that establishes a tree of shortest paths from a source to that establishes a tree of shortest paths from a source to
destinations on the graph. SPF acronym is used due to its destinations on the graph. The SPF acronym is used due to its
familiarity as general term for the node reachability calculations familiarity as a general term for the node reachability
RIFT can employ to ultimately calculate routes of which Dijkstra calculations RIFT can employ to ultimately calculate routes, of
algorithm is a possible one. which Dijkstra's algorithm is a possible one.
South Reflection: South Reflection:
Often abbreviated just as "reflection", it defines a mechanism Often abbreviated just as "reflection", it defines a mechanism
where South Node TIEs are "reflected" from the level south back up where South Node TIEs are "reflected" from the level south back up
north to allow nodes in the same level without E-W links to be north to allow nodes in the same level without E-W links to be
aware of each other's node Topology Information Elements (TIEs). aware of each other's node Topology Information Elements (TIEs).
South SPF (S-SPF): South SPF (S-SPF):
A reachability calculation that is progressing southbound, as A reachability calculation that is progressing southbound, for
example SPF that is using North Node TIEs only. example, SPF that is using North Node TIEs only.
South/Southbound and North/Northbound (Direction): South/Southbound and North/Northbound (Direction):
When describing protocol elements and procedures, in different When describing protocol elements and procedures, in different
situations the directionality of the compass is used. i.e., situations, the directionality of the compass is used, i.e.,
'lower', 'south' or 'southbound' mean moving towards the bottom of "lower", "south", and "southbound" mean moving towards the bottom
the Clos or Fat Tree network and 'higher', 'north' and of the Clos or Fat Tree network and "higher", "north", and
'northbound' mean moving towards the top of the Clos or Fat Tree "northbound" mean moving towards the top of the Clos or Fat Tree
network. network.
Southbound Link: Southbound Link:
A link to a node one level down or in other words, one level A link to a node one level down or, in other words, one level
further south. further south.
Southbound representation: Southbound Representation:
Subset of topology information sent towards a lower level. The subset of topology information sent towards a lower level.
Spine: Spine:
Any nodes north of leaves and south of ToF nodes. Multiple layers Any nodes north of leaves and south of ToF nodes. Multiple layers
of spines in a PoD are possible. of spines in a PoD are possible.
Superspine, Aggregation/Spine and Edge/Leaf Switches:" Superspine, Aggregation/Spine, and Edge/Leaf Switches:
Traditional level names in 5-stages folded Clos for Level 2, 1 and Traditional level names in 5 stages folded Clos for levels 2, 1,
0 respectively (counting up from the bottom). We normalize this and 0, respectively (counting up from the bottom). We normalize
language to talk about ToF, Top-of-Pod (ToP) and leaves. this language to talk about ToF, Top-of-Pod (ToP), and leaves.
System ID: System ID:
RIFT nodes identify themselves with a unique network-wide number RIFT nodes identify themselves with a unique network-wide number
when trying to build adjacencies or describe their topology. RIFT when trying to build adjacencies or describe their topology. RIFT
System IDs can be auto-derived or configured. System IDs can be auto-derived or configured.
ThreeWay Adjacency: ThreeWay Adjacency:
RIFT tries to form a unique adjacency between two nodes over a RIFT tries to form a unique adjacency between two nodes over a
point-to-point interface and exchange local configuration and point-to-point interface and exchange local configuration and
necessary RIFT ZTP information. An adjacency is only advertised necessary RIFT ZTP information. An adjacency is only advertised
in Node TIEs and used for computations after it achieved in Node TIEs and used for computations after it achieved
_ThreeWay_ state, i.e. both routers reflected each other in LIEs _ThreeWay_ state, i.e., both routers reflected each other in LIEs,
including relevant security information. Nevertheless, LIEs including relevant security information. Nevertheless, LIEs
before _ThreeWay_ state is reached may carry RIFT ZTP related before _ThreeWay_ state is reached may already carry information
information already. related to RIFT ZTP.
TIDE: TIDE:
Topology Information Description Element carrying descriptors of The Topology Information Description Element carries descriptors
the TIEs stored in the node. of the TIEs stored in the node.
TIE: TIE:
This is an acronym for a "Topology Information Element". TIEs are This is an acronym for a "Topology Information Element". TIEs are
exchanged between RIFT nodes to describe parts of a network such exchanged between RIFT nodes to describe parts of a network such
as links and address prefixes. A TIE has always a direction and a as links and address prefixes. A TIE always has a direction and a
type. North TIEs (sometimes abbreviated as N-TIEs) are used when type. North TIEs (sometimes abbreviated as N-TIEs) are used when
dealing with TIEs in the northbound representation and South-TIEs dealing with TIEs in the northbound representation, and South-TIEs
(sometimes abbreviated as S-TIEs) for the southbound equivalent. are used (sometimes abbreviated as S-TIEs) for the southbound
TIEs have different types such as node and prefix TIEs. equivalent. TIEs have different types, such as node and prefix
TIEs.
TIEDB: TIEDB:
The database holding the newest versions of all TIE headers (and The database holding the newest versions of all TIE headers (and
the corresponding TIE content if it is available). the corresponding TIE content if it is available).
TIRE: TIRE:
Topology Information Request Element carrying set of TIDE The Topology Information Request Element carries a set of TIDE
descriptors. It can both confirm received and request missing descriptors. It can both confirm received and request missing
TIEs. TIEs.
Top of Fabric (ToF): Top of Fabric (ToF):
The set of nodes that provide inter-PoD communication and have no The set of nodes that provide inter-PoD communication and have no
northbound adjacencies, i.e. are at the "very top" of the fabric. northbound adjacencies, i.e., are at the "very top" of the fabric.
ToF nodes do not belong to any PoD and are assigned ToF nodes do not belong to any PoD and are assigned the
_common.default_pod_ PoD value to indicate the equivalent of "any" _common.default_pod_ PoD value to indicate the equivalent of "any"
PoD. PoD.
Top of PoD (ToP): Top of PoD (ToP):
The set of nodes that provide intra-PoD communication and have The set of nodes that provide intra-PoD communication and have
northbound adjacencies outside of the PoD, i.e. are at the "top" northbound adjacencies outside of the PoD, i.e., are at the "top"
of the PoD. of the PoD.
ToF Plane or Partition: ToF Plane or Partition:
In large fabrics ToF switches may not have enough ports to In large fabrics, ToF switches may not have enough ports to
aggregate all switches south of them and with that, the ToF is aggregate all switches south of them, and with that, the ToF is
'split' into multiple independent planes. Section 5.2 explains "split" into multiple independent planes. Section 5.2 explains
the concept in more detail. A plane is a subset of ToF nodes that the concept in more detail. A plane is a subset of ToF nodes that
are aware of each other through south reflection or E-W links. are aware of each other through south reflection or E-W links.
Valid LIE: Valid LIE:
LIEs undergo different checks to determine their validity. The LIEs undergo different checks to determine their validity. The
term "valid LIE" is used to describe a LIE that can be used to term "valid LIE" is used to describe a LIE that can be used to
form or maintain an adjacency. The amount of checking itself form or maintain an adjacency. The amount of checking itself
depends on the FSM (Finite State Machine) involved and its state. depends on the Finite State Machine (FSM) involved and its state.
A "minimally valid LIE" is a LIE that passes checks necessary on A "minimally valid LIE" is a LIE that passes checks necessary on
any FSM in any state. A "ThreeWay valid LIE" is a LIE that any FSM in any state. A "ThreeWay valid LIE" is a LIE that
successfully underwent further checks with a LIE FSM in _ThreeWay_ successfully underwent further checks with a LIE FSM in _ThreeWay_
state. Minimally valid LIE is a subcategory of _ThreeWay_ valid state. A minimally valid LIE is a subcategory of a _ThreeWay_
LIE. valid LIE.
RIFT Zero Touch Provisioning (abbreviated as RIFT ZTP or just RIFT Zero Touch Provisioning (abbreviated as RIFT ZTP or just
ZTP): ZTP):
Optional RIFT mechanism which allows the automatic derivation of An optional RIFT mechanism that allows the automatic derivation of
node levels based on minimum configuration as detailed in node levels based on minimum configuration, as detailed in
Section 6.7. Such a mininum configuration consists solely of ToFs Section 6.7. Such a minimum configuration consists solely of ToFs
being configured as such. RIFT ZTP contains a recommendation for being configured as such. RIFT ZTP contains a recommendation for
automatic collision-free derivation of the System ID as well. automatic collision-free derivation of the System ID as well.
Additionally, when the specification refers to elements of packet Additionally, when the specification refers to elements of packet
encoding or constants provided in the Section 7 a special emphasis is encoding or the constants provided in Section 7, a special emphasis
used, e.g. _invalid_distance_. The same convention is used when is used, e.g., _invalid_distance_. The same convention is used when
referring to finite state machine states or events outside the referring to finite state machine states or events outside the
context of the machine itself, e.g., _OneWay_. context of the machine itself, e.g., _OneWay_.
3.2. Topology 3.2. Topology
^ N +--------+ +--------+ ^ N +--------+ +--------+
Level 2 | |ToF 21| |ToF 22| Level 2 | |ToF 21| |ToF 22|
W <-*-> E ++-+--+-++ ++-+--+-++ W <-*-> E ++-+--+-++ ++-+--+-++
| | | | | | | | | | | | | | | | | |
S v P111/2 P121/2 | | | | S v P111/2 P121/2 | | | |
^ ^ ^ ^ | | | | ^ ^ ^ ^ | | | |
| | | | | | | | | | | | | | | |
+--------------+ | +-----------+ | | | +---------------+ +--------------+ | +-----------+ | | | +---------------+
| | | | | | | | | | | | | | | |
South +-----------------------------+ | | ^ South +-----------------------------+ | | ^
skipping to change at page 17, line 34 skipping to change at line 767
| +---0/0--->-----+ 0/0 | +----------------+ | | +---0/0--->-----+ 0/0 | +----------------+ |
0/0 | | | | | | | 0/0 | | | | | | |
| +---<-0/0-----+ | v | +--------------+ | | | +---<-0/0-----+ | v | +--------------+ | |
v | | | | | | | v | | | | | | |
+-+---+-+ +--+--+-+ +-+---+-+ +---+-+-+ +-+---+-+ +--+--+-+ +-+---+-+ +---+-+-+
Level 0 | | (L2L) | | | | | | Level 0 | | (L2L) | | | | | |
|Leaf111+~~~~~~~~~~+Leaf112| |Leaf121| |Leaf122| |Leaf111+~~~~~~~~~~+Leaf112| |Leaf121| |Leaf122|
+-+-----+ +-+---+-+ +--+--+-+ +-+-----+ +-+-----+ +-+---+-+ +--+--+-+ +-+-----+
+ + \ / + + + + \ / + +
Prefix111 Prefix112 \ / Prefix121 Prefix122 Prefix111 Prefix112 \ / Prefix121 Prefix122
multi-homed multihomed
Prefix Prefix
+---------- PoD 1 ---------+ +---------- PoD 2 ---------+ +---------- PoD 1 ---------+ +---------- PoD 2 ---------+
Figure 2: A Three Level Spine-and-Leaf Topology Figure 2: A Three-Level Spine-and-Leaf Topology
____________________________________________________________________________ ____________________________________________________________________________
| [Plane A] . [Plane B] . [Plane C] . [Plane D] | | [Plane A] . [Plane B] . [Plane C] . [Plane D] |
|..........................................................................| |..........................................................................|
| +-+ . +-+ . +-+ . +-+ | | +-+ . +-+ . +-+ . +-+ |
| |n| . |n| . |n| . |n| | | |n| . |n| . |n| . |n| |
| +++ . +++ . +++ . +++ | | +++ . +++ . +++ . +++ |
| . | | . . | | . . | | . . | | | | . | | . . | | . . | | . . | | |
| . | | . . | | . . | | . . | | | | . | | . . | | . . | | . . | | |
| +-+ | | . +-+ | | . +-+ | | . +-+ | | | | +-+ | | . +-+ | | . +-+ | | . +-+ | | |
skipping to change at page 18, line 46 skipping to change at line 827
/ || || || || || || || || / +++-+++ / / || || || || || || || || / +++-+++ /
/ +++-+++ +++-+++ +++-+++ +++-+++/=========/ / +++-+++ +++-+++ +++-+++ +++-+++/=========/
/ | 1 | | 2 + | 3 | . . . | n |/ ^^ / | 1 | | 2 + | 3 | . . . | n |/ ^^
/ +++-+++ +-----+ +-----+ +-----+/ // / +++-+++ +-----+ +-----+ +-----+/ //
/ / PoDs / / PoDs
================================================================== // ================================================================== //
Figure 3: Topology with Multiple Planes Figure 3: Topology with Multiple Planes
The topology in Figure 2 is referred to in all further The topology in Figure 2 is referred to in all further
considerations. This figure depicts a generic "single plane fat considerations. This figure depicts a generic "single plane Fat
tree" and the concepts explained using three levels apply by Tree" and the concepts explained using three levels apply by
induction to further levels and higher degrees of connectivity. induction to further levels and higher degrees of connectivity.
Further, this document will deal also with designs that provide only Further, this document will also deal with designs that provide only
sparser connectivity and "partitioned spines" as shown in Figure 3 sparser connectivity and "partitioned spines", as shown in Figure 3
and explained further in Section 5.2. and explained further in Section 5.2.
4. RIFT: Routing in Fat Trees 4. RIFT: Routing in Fat Trees
The remainder of this document presents the detailed specification of The remainder of this document presents the detailed specification of
the RIFT protocol, which in the most abstract terms has many the RIFT protocol, which in the most abstract terms has many
properties of a modified link-state protocol when distributing properties of a modified link-state protocol when distributing
information northbound and a distance vector protocol when information northbound and a distance-vector protocol when
distributing information southbound. While this is an unusual distributing information southbound. While this is an unusual
combination, it does quite naturally exhibit desired properties. combination, it does quite naturally exhibit desired properties.
5. Overview 5. Overview
5.1. Properties 5.1. Properties
The most singular property of RIFT is that it floods link-state The most singular property of RIFT is that it only floods link-state
information northbound only so that each level obtains the full information northbound so that each level obtains the full topology
topology of levels south of it. Link-State information is, with some of levels south of it. Link-State information is, with some
exceptions, not flooded East-West nor back South again. Exceptions exceptions, not flooded East-West nor back south again. Exceptions
like south reflection is explained in detail in Section 6.5.1 and like south reflection is explained in detail in Section 6.5.1, and
east-west flooding at ToF level in multi-plane fabrics is outlined in east-west flooding at the ToF level in multi-plane fabrics is
Section 5.2. In the southbound direction, the necessary routing outlined in Section 5.2. In the southbound direction, the necessary
information required (normally just a default route as per routing information required (normally just a default route as per
Section 6.3.8) only propagates one hop south. Those nodes then Section 6.3.8) only propagates one hop south. Those nodes then
generate their own routing information and flood it south to avoid generate their own routing information and flood it south to avoid
the overhead of building an update per adjacency. For the moment the overhead of building an update per adjacency. For the moment,
describing the East-West direction is left out until later in the describing the East-West direction is left out until later in the
document. document.
Those information flow constraints create not only an anisotropic Those information flow constraints create not only an anisotropic
protocol (i.e. the information is not distributed "evenly" or protocol (i.e., the information is not distributed "evenly" or
"clumped" but summarized along the N-S gradient) but also a "smooth" "clumped" but summarized along the north-south gradient) but also a
information propagation where nodes do not receive the same "smooth" information propagation where nodes do not receive the same
information from multiple directions at the same time. Normally, information from multiple directions at the same time. Normally,
accepting the same reachability on any link, without understanding accepting the same reachability on any link, without understanding
its topological significance, forces tie-breaking on some kind of its topological significance, forces tie-breaking on some kind of
distance function. And such tie-breaking leads ultimately to hop-by- distance function. And such tie-breaking ultimately leads to hop-by-
hop forwarding by shortest paths only. In contrast to that, RIFT, hop forwarding by shortest paths only. In contrast to that, RIFT,
under normal conditions, does not need to tie-break the same under normal conditions, does not need to tie-break the same
reachability information from multiple directions. Its computation reachability information from multiple directions. Its computation
principles (south forwarding direction is always preferred) leads to principles (south forwarding direction is always preferred) lead to
valley-free [VFR] forwarding behavior. In shortest terms, valley valley-free [VFR] forwarding behavior. In the shortest terms,
free paths allow reversal of direction at most once from a packet valley-free paths allow reversal of direction from a packet heading
heading northbound to southbound while permitting traversal of northbound to southbound while permitting traversal of horizontal
horizontal links in the northbound phase. Those principles guarantee links in the northbound phase at most once. Those principles
loop-free forwarding and with that can take advantage of all such guarantee loop-free forwarding and with that can take advantage of
feasible paths on a fabric. This is another highly desirable all such feasible paths on a fabric. This is another highly
property if available bandwidth should be utilized to the maximum desirable property if available bandwidth should be utilized to the
extent possible. maximum extent possible.
To account for the "northern" and the "southern" information split To account for the "northern" and the "southern" information split,
the link state database is partitioned accordingly into "north the link state database is partitioned accordingly into "north
representation" and "south representation" Topology Information representation" and "south representation" Topology Information
Elements (TIEs). In simplest terms the North TIEs contain a link Elements (TIEs). In the simplest terms, the North TIEs contain a
state topology description of lower levels and South TIEs carry link-state topology description of lower levels and South TIEs simply
simply node description of the level above and default routes carry a node description of the level above and default routes
pointing north. This oversimplified view will be refined gradually pointing north. This oversimplified view will be refined gradually
in the following sections while introducing protocol procedures and in the following sections while introducing protocol procedures and
state machines at the same time. state machines at the same time.
5.2. Generalized Topology View 5.2. Generalized Topology View
This section and resulting Section 6.5.2 are dedicated to multi-plane This section and Section 6.5.2 are dedicated to multi-plane fabrics,
fabrics, in contrast with the single plane designs where all ToF in contrast with the single plane designs where all ToF nodes are
nodes are topologically equal and initially connected to all the topologically equal and initially connected to all the switches at
switches at the level below them. the level below them.
Multi-plane design is effectively a multi-dimensional switching The multi-plane design is effectively a multidimensional switching
matrix. To make that easier to visualize, this document introduces a matrix. To make that easier to visualize, this document introduces a
methodology depicting the connectivity in two-dimensional pictures. methodology depicting the connectivity in two-dimensional pictures.
Further, it can be leveraged that what is under consideration here Further, it can be leveraged that what is under consideration here is
are basically stacked crossbar fabrics where ports align "on top of basically stacked crossbar fabrics where ports align "on top of each
each other" in a regular fashion. other" in a regular fashion.
A word of caution to the reader; at this point it should be observed A word of caution to the reader: At this point, it should be observed
that the language used to describe Clos variations, especially in that the language used to describe Clos variations, especially in
multi-plane designs, varies widely between sources. This description multi-plane designs, varies widely between sources. This description
follows the terminology introduced in Section 3.1. This terminology follows the terminology introduced in Section 3.1. This terminology
is needed to follow the rest of this section correctly. is needed to follow the rest of this section correctly.
5.2.1. Terminology and Glossary 5.2.1. Terminology and Glossary
This section describes the terminology and abbreviations used in the This section describes the terminology and abbreviations used in the
rest of the text. Though the glossary may not be clear on a first rest of the text. Though the glossary may not be clear on a first
read, the following sections will introduce the terms in their proper read, the following sections will introduce the terms in their proper
context. context.
P: P:
Denotes the number of PoDs in a topology. Denotes the number of PoDs in a topology.
S: S:
Denotes the number of ToF nodes in a topology. Denotes the number of ToF nodes in a topology.
K: K:
To simplify the visual aids, notations and further considerations, To simplify the visual aids, notations, and further
the assumption is made that the switches are symmetrical, i.e., considerations, the assumption is made that the switches are
they have an equal number of ports pointing northbound and symmetrical, i.e., they have an equal number of ports pointing
southbound. With that simplification, K denotes half of the radix northbound and southbound. With that simplification, K denotes
of a symmetrical switch, meaning that the switch has K ports half of the radix of a symmetrical switch, meaning that the switch
pointing north and K ports pointing south. K_LEAF (K of a leaf) has K ports pointing north and K ports pointing south. K_LEAF (K
thus represents both the number of access ports in a leaf Node and of a leaf) thus represents both the number of access ports in a
the maximum number of planes in the fabric, whereas K_TOP (K of a leaf node and the maximum number of planes in the fabric, whereas
ToP) represents the number of leaves in the PoD and the number of K_TOP (K of a ToP) represents the number of leaves in the PoD and
ports pointing north in a ToP Node towards a higher spine level the number of ports pointing north in a ToP Node towards a higher
and thus the number of ToF nodes in a plane. spine level and thus the number of ToF nodes in a plane.
ToF Plane: ToF Plane:
Set of ToFs that are aware of each other by means of south Set of ToFs that are aware of each other by means of south
reflection. Planes are designated by capital letters, e.g. plane reflection. Planes are designated by capital letters, e.g., plane
A. A.
N: N:
Denotes the number of independent ToF planes in a topology. Denotes the number of independent ToF planes in a topology.
R: R:
Denotes a redundancy factor, i.e., number of connections a spine Denotes a redundancy factor, i.e., the number of connections a
has towards a ToF plane. In single plane design K_TOP is equal to spine has towards a ToF plane. In a single plane design, K_TOP is
R. equal to R.
Fallen Leaf: Fallen Leaf:
A fallen leaf in a plane Z is a switch that lost all connectivity A fallen leaf in a plane Z is a switch that lost all connectivity
northbound to Z. northbound to Z.
5.2.2. Clos as Crossed, Stacked Crossbars 5.2.2. Clos as Crossed, Stacked Crossbars
The typical topology for which RIFT is defined is built of P number The typical topology for which RIFT is defined is built of P number
of PoDs and connected together by S number of ToF nodes. A PoD node of PoDs and connected together by S number of ToF nodes. A PoD node
has K number of ports. From here on half of them (K=Radix/2) are has K number of ports. From here on, half of them (K=Radix/2) are
assumed to connect host devices from the south, and the other half to assumed to connect host devices from the south, and the other half is
connect to interleaved PoD Top-Level switches to the north. The K assumed to connect to interleaved PoD top-level switches to the
ratio can be chosen differently without loss of generality when port north. The K ratio can be chosen differently without loss of
speeds differ or the fabric is oversubscribed but K=Radix/2 allows generality when port speeds differ or the fabric is oversubscribed,
for more readable representation whereby there are as many ports but K=Radix/2 allows for more readable representation whereby there
facing north as south on any intermediate node. A node is hence are as many ports facing north as south on any intermediate node. A
represented in a schematic fashion with ports "sticking out" to its node is hence represented in a schematic fashion with ports "sticking
north and south rather than by the usual real-world front faceplate out" to its north and south, rather than by the usual real-world
designs of the day. front faceplate designs of the day.
Figure 4 provides a view of a leaf node as seen from the north, i.e. Figure 4 provides a view of a leaf node as seen from the north, i.e.,
showing ports that connect northbound. For lack of a better symbol, showing ports that connect northbound. For lack of a better symbol,
the document chooses to use the "o" as ASCII visualisation of a the document chooses to use the "o" as ASCII visualization of a
single port. In this example, K_LEAF has 6 ports. Observe that the single port. In this example, K_LEAF has 6 ports. Observe that the
number of PoDs is not related to Radix unless the ToF Nodes are number of PoDs is not related to the Radix unless the ToF nodes are
constrained to be the same as the PoD nodes in a particular constrained to be the same as the PoD nodes in a particular
deployment. deployment.
Top view Top View
+---+ +---+
| | | |
| O | e.g., Radix = 12, K_LEAF = 6 | o | e.g., Radix = 12, K_LEAF = 6
| | | |
| O | | o |
| | ------------------------- | | -------------------------
| o <------ Physical Port (Ethernet) ----+ | o <------ Physical Port (Ethernet) ----+
| | ------------------------- | | | ------------------------- |
| O | | | o | |
| | | | | |
| O | | | o | |
| | | | | |
| O | | | o | |
| | | | | |
+---+ v +---+ v
|| || || || || || || || || || || || || ||
+----+ +------------------------------------------------+ +----+ +------------------------------------------------+
| | | | | | | |
+----+ +------------------------------------------------+ +----+ +------------------------------------------------+
|| || || || || || || || || || || || || ||
Side views Side Views
Figure 4: A Leaf Node, K_LEAF=6 Figure 4: A Leaf Node, K_LEAF=6
The Radix of a PoD's top node may be different than that of the leaf The Radix of a PoD's top node may be different than that of the leaf
node. Though, more often than not, a same type of node is used for node. Though, more often than not, a same type of node is used for
both, effectively forming a square (K*K). In the general case, both, effectively forming a square (K*K). In the general case,
switches at the top of the PoD with K_TOP southern ports not switches at the top of the PoD with K_TOP southern ports not
necessarily equal to K_LEAF could be considered . For instance, in necessarily equal to K_LEAF could be considered . For instance, in
the representations below, we pick a 6 port K_LEAF and an 8 port the representations below, we pick a 6-port K_LEAF and an 8-port
K_TOP. In order to form a crossbar, K_TOP Leaf Nodes are necessary K_TOP. In order to form a crossbar, K_TOP leaf nodes are necessary
as illustrated in Figure 5. as illustrated in Figure 5.
+---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O | | O |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
+---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
Figure 5: Southern View of Leaf Nodes of a PoD, K_TOP=8 Figure 5: Southern View of Leaf Nodes of a PoD, K_TOP=8
As further visualized in Figure 6 the K_TOP Leaf Nodes are fully As further visualized in Figure 6, the K_TOP leaf nodes are fully
interconnected with the K_LEAF ToP nodes, providing connectivity that interconnected with the K_LEAF ToP nodes, providing connectivity that
can be represented as a crossbar when "looked at" from the north. can be represented as a crossbar when "looked at" from the north.
The result is that, in the absence of a failure, a packet entering The result is that, in the absence of a failure, a packet entering
the PoD from the north on any port can be routed to any port in the the PoD from the north on any port can be routed to any port in the
south of the PoD and vice versa. And that is precisely why it makes south of the PoD and vice versa. And that is precisely why it makes
sense to talk about a "switching matrix". sense to talk about a "switching matrix".
W <---*---> E W <---*---> E
+---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
skipping to change at page 24, line 37 skipping to change at line 1071
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
+---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ | +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ |
^ | ^ |
| | | |
| ---------- ----------------------- | | ---------- ----------------------- |
+----- Leaf Node Top-of-PoD Node (Spine) --+ +----- Leaf Node Top-of-PoD Node (Spine) --+
---------- ----------------------- ---------- -----------------------
Figure 6: Northern View of a PoD's Spines, K_TOP=8 Figure 6: Northern View of a PoD's Spines, K_TOP=8
Side views of this PoD is illustrated in Figure 7 and Figure 8. Side views of this PoD is illustrated in Figures 7 and 8.
Connecting to Spine Nodes Connecting to Spine Nodes
|| || || || || || || || || || || || || || || ||
+----------------------------------------------------------------+ N +----------------------------------------------------------------+ N
| Top-of-PoD Node (Sideways) | ^ | Top-of-PoD Node (Sideways) | ^
+----------------------------------------------------------------+ | +----------------------------------------------------------------+ |
|| || || || || || || || * || || || || || || || || *
+----+ +----+ +----+ +----+ +----+ +----+ +----+ +----+ | +----+ +----+ +----+ +----+ +----+ +----+ +----+ +----+ |
|Leaf| |Leaf| |Leaf| |Leaf| |Leaf| |Leaf| |Leaf| |Leaf| v |Leaf| |Leaf| |Leaf| |Leaf| |Leaf| |Leaf| |Leaf| |Leaf| v
skipping to change at page 25, line 25 skipping to change at line 1108
+------------------------------------------------+ v +------------------------------------------------+ v
| Leaf Node (Sideways) | S | Leaf Node (Sideways) | S
+------------------------------------------------+ +------------------------------------------------+
Connecting to Client Nodes Connecting to Client Nodes
Figure 8: Other Side View of a PoD, K_TOP=8, K_LEAF=6, 90-Degree Figure 8: Other Side View of a PoD, K_TOP=8, K_LEAF=6, 90-Degree
Turn in E-W Plane from the Previous Figure Turn in E-W Plane from the Previous Figure
As a next step, observe that a resulting PoD can be abstracted as a As a next step, observe that a resulting PoD can be abstracted as a
bigger node with a number K of K_POD= K_TOP * K_LEAF, and the design bigger node with a number K of K_POD = K_TOP * K_LEAF, and the design
can recurse. can recurse.
It will be critical at this point that, before progressing further, It will be critical at this point that, before progressing further,
the concept and the picture of "crossed crossbars" is understood. the concept and the picture of "crossed crossbars" is understood.
Else, the following considerations might be difficult to comprehend. Else, the following considerations might be difficult to comprehend.
To continue, the PoDs are interconnected with each other through a To continue, the PoDs are interconnected with each other through a
ToF node at the very top or the north edge of the fabric. The ToF node at the very top or the north edge of the fabric. The
resulting ToF is *not* partitioned if, and only if (IIF), every PoD resulting ToF is *not* partitioned if and only if (IIF) every PoD
top level node (spine) is connected to every ToF Node. This topology top-level node (spine) is connected to every ToF node. This topology
is also referred to as a single plane configuration and is quite is also referred to as a single plane configuration and is quite
popular due to its simplicity. In order to reach a 1:1 connectivity popular due to its simplicity. There are K_TOP ToF nodes and K_LEAF
ratio between the ToF and the leaves, it results that there are K_TOP ToP nodes because each port of a ToP node connects to a different ToF
ToF nodes, because each port of a ToP node connects to a different node. Consequently, it will take at least P * K_LEAF ports on a ToF
ToF node, and K_LEAF ToP nodes for the same reason. Consequently, it node to connect to each of the K_LEAF ToP nodes of the P PoDs.
will take at least (P * K_LEAF) ports on a ToF node to connect to Figure 9 illustrates this, looking at P=3 PoDs from above and 2
each of the K_LEAF ToP nodes of the P PoDs. Figure 9 illustrates sides. The large view is the one from above, with the 8 ToF of 3 * 6
this, looking at P=3 PoDs from above and 2 sides. The large view is ports each interconnecting the PoDs and every ToP Node being
the one from above, with the 8 ToF of 3*6 ports each interconnecting connected to every ToF node.
the PoDs, every ToP Node being connected to every ToF node.
[ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] <-----+ [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] <-----+
| | | | | | | | | | | | | | | | | |
[=================================] | -------------- [=================================] | --------------
| | | | | | | | +----- ToF | | | | | | | | +----- ToF
[ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] +----- Node ---+ [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] +----- Node ---+
| -------------- | | -------------- |
| v | v
+-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ <-----+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ <-----+ +-+
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
skipping to change at page 26, line 37 skipping to change at line 1161
| | | | | | | | | | | | | | | | -+ +- +-+ v | | | | | | | | | | | | | | | | | | -+ +- +-+ v | |
[ |o| |o| |o| |o| |o| |o| |o| |o| ] | | --| |--[ ]--| | [ |o| |o| |o| |o| |o| |o| |o| |o| ] | | --| |--[ ]--| |
[ |o| |o| |o| |o| |o| |o| |o| |o| ] | ----- | --| |--[ ]--| | [ |o| |o| |o| |o| |o| |o| |o| |o| ] | ----- | --| |--[ ]--| |
[ |o| |o| |o| |o| |o| |o| |o| |o| ] +--- PoD ---+ --| |--[ ]--| | [ |o| |o| |o| |o| |o| |o| |o| |o| ] +--- PoD ---+ --| |--[ ]--| |
[ |o| |o| |o| |o| |o| |o| |o| |o| ] | ----- | --| |--[ ]--| | [ |o| |o| |o| |o| |o| |o| |o| |o| ] | ----- | --| |--[ ]--| |
[ |o| |o| |o| |o| |o| |o| |o| |o| ] | | --| |--[ ]--| | [ |o| |o| |o| |o| |o| |o| |o| |o| ] | | --| |--[ ]--| |
[ |o| |o| |o| |o| |o| |o| |o| |o| ] | | --| |--[ ]--| | [ |o| |o| |o| |o| |o| |o| |o| |o| ] | | --| |--[ ]--| |
| | | | | | | | | | | | | | | | -+ +- +-+ | | | | | | | | | | | | | | | | | | -+ +- +-+ | |
+-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+
Figure 9: Fabric Spines and TOFs in Single Plane Design, 3 PoDs Figure 9: Fabric Spines and ToFs in Single Plane Design, 3 PoDs
The top view can be collapsed into a third dimension where the hidden The top view can be collapsed into a third dimension where the hidden
depth index is representing the PoD number. One PoD can be shown depth index is representing the PoD number. One PoD can be shown
then as a class of PoDs and hence save one dimension in the then as a class of PoDs and hence save one dimension in the
representation. The Spine Node expands in the depth and the vertical representation. The spine node expands in the depth and the vertical
dimensions, whereas the PoD top level Nodes are constrained, in dimensions, whereas the PoD top-level nodes are constrained in the
horizontal dimension. A port in the 2-D representation represents horizontal dimension. A port in the 2-D representation effectively
effectively the class of all the ports at the same position in all represents the class of all the ports at the same position in all the
the PoDs that are projected in its position along the depth axis. PoDs that are projected in its position along the depth axis. This
This is shown in Figure 10. is shown in Figure 10.
/ / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /
/ / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /
/ / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /
/ / / / / / / / / / / / / / / / ] / / / / / / / / / / / / / / / / ]
+-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ ]] +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ ]]
| | | | | | | | | | | | | | | | ] ----------------------- | | | | | | | | | | | | | | | | ] -----------------------
[ |o| |o| |o| |o| |o| |o| |o| |o| ] <-- Top of PoD Node (Spine) [ |o| |o| |o| |o| |o| |o| |o| |o| ] <-- Top of PoD Node (Spine)
[ |o| |o| |o| |o| |o| |o| |o| |o| ] ----------------------- [ |o| |o| |o| |o| |o| |o| |o| |o| ] -----------------------
[ |o| |o| |o| |o| |o| |o| |o| |o| ]]]] [ |o| |o| |o| |o| |o| |o| |o| |o| ]]]]
skipping to change at page 27, line 32 skipping to change at line 1200
-------- --------
Figure 10: Collapsed Northern View of a Fabric for Any Number of PoDs Figure 10: Collapsed Northern View of a Fabric for Any Number of PoDs
As simple as a single plane deployment is, it introduces a limit due As simple as a single plane deployment is, it introduces a limit due
to the bound on the available radix of the ToF nodes that has to be to the bound on the available radix of the ToF nodes that has to be
at least P * K_LEAF. Nevertheless, it will become clear that a at least P * K_LEAF. Nevertheless, it will become clear that a
distinct advantage of a connected or non-partitioned ToF is that all distinct advantage of a connected or non-partitioned ToF is that all
failures can be resolved by simple, non-transitive, positive failures can be resolved by simple, non-transitive, positive
disaggregation (i.e., nodes advertising more specific prefixes with disaggregation (i.e., nodes advertising more specific prefixes with
the default to the level below them that is, however, not propagated the default to the level below them that is not propagated further
further down the fabric) as described in Section 6.5.1 . In other down the fabric) as described in Section 6.5.1. In other words, non-
words, non-partitioned ToF nodes can always reach nodes below or partitioned ToF nodes can always reach nodes below or withdraw the
withdraw the routes from PoDs they cannot reach unambiguously. And routes from PoDs they cannot reach unambiguously. And with this,
with this, positive disaggregation can heal all failures and still positive disaggregation can heal all failures and still allow all the
allow all the ToF nodes to be aware of each other via south ToF nodes to be aware of each other via south reflection.
reflection. Disaggregation will be explained in further detail in Disaggregation will be explained in further detail in Section 6.5.
Section 6.5.
In order to scale beyond the "single plane limit", the ToF can be In order to scale beyond the "single plane limit", the ToF can be
partitioned into N number of identically wired planes where N is an partitioned into N number of identically wired planes where N is an
integer divider of K_LEAF. The 1:1 ratio and the desired symmetry integer divider of K_LEAF. The 1:1 ratio and the desired symmetry
are still served, this time with (K_TOP * N) ToF nodes, each of (P * are still served, this time with (K_TOP*N) ToF nodes, each of
K_LEAF / N) ports. N=1 represents a non-partitioned Spine and (P*K_LEAF/N) ports. N=1 represents a non-partitioned Spine, and
N=K_LEAF is a maximally partitioned Spine. Further, if R is any N=K_LEAF is a maximally partitioned Spine. Further, if R is any
integer divisor of K_LEAF, then N=K_LEAF/R is a feasible number of integer divisor of K_LEAF, then N=K_LEAF/R is a feasible number of
planes and R a redundancy factor that denotes the number of planes and R is a redundancy factor that denotes the number of
independent paths between 2 leaves within a plane. It proves independent paths between 2 leaves within a plane. It proves
convenient for deployments to use a radix for the leaf nodes that is convenient for deployments to use a radix for the leaf nodes that is
a power of 2 so they can pick a number of planes that is a lower a power of 2 so they can pick a number of planes that is a lower
power of 2. The example in Figure 11 splits the Spine in 2 planes power of 2. The example in Figure 11 splits the Spine in 2 planes
with a redundancy factor R=3, meaning that there are 3 non- with a redundancy factor of R=3, meaning that there are 3 non-
intersecting paths between any leaf node and any ToF node. A ToF intersecting paths between any leaf node and any ToF node. A ToF
node must have, in this case, at least 3*P ports, and be directly node must have, in this case, at least 3*P ports and be directly
connected to 3 of the 6 ToP nodes (spines) in each PoD. The ToP connected to 3 of the 6 ToP nodes (spines) in each PoD. The ToP
nodes are represented horizontally with K_TOP=8 ports northwards nodes are represented horizontally with K_TOP=8 ports northwards
each. each.
+---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
+-| |--| |--| |--| |--| |--| |--| |--| |-+ +-| |--| |--| |--| |--| |--| |--| |--| |-+
| | O | | O | | O | | O | | O | | O | | O | | O | | | | O | | O | | O | | O | | O | | O | | O | | O | |
+-| |--| |--| |--| |--| |--| |--| |--| |-+ +-| |--| |--| |--| |--| |--| |--| |--| |-+
+-| |--| |--| |--| |--| |--| |--| |--| |-+ +-| |--| |--| |--| |--| |--| |--| |--| |-+
| | O | | O | | O | | O | | O | | O | | O | | O | | | | O | | O | | O | | O | | O | | O | | O | | O | |
skipping to change at page 29, line 5 skipping to change at line 1262
+-| |--| |--| |--| |--| |--| |--| |--| |-+ +-| |--| |--| |--| |--| |--| |--| |--| |-+
+---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
^ ^
| |
| --------------------- | ---------------------
+----- ToF Node Across Depth +----- ToF Node Across Depth
--------------------- ---------------------
Figure 11: Northern View of a Multi-Plane ToF Level, K_LEAF=6, N=2 Figure 11: Northern View of a Multi-Plane ToF Level, K_LEAF=6, N=2
At the extreme end of the spectrum it is even possible to fully At the extreme end of the spectrum, it is even possible to fully
partition the spine with N = K_LEAF and R=1, while maintaining partition the spine with N=K_LEAF and R=1 while maintaining
connectivity between each leaf node and each ToF node. In that case connectivity between each leaf node and each ToF node. In that case,
the ToF node connects to a single Port per PoD, so it appears as a the ToF node connects to a single port per PoD, so it appears as a
single port in the projected view represented in Figure 12. The single port in the projected view represented in Figure 12. The
number of ports required on the Spine Node is more than or equal to number of ports required on the spine node is more than or equal to
P, the number of PoDs. P, i.e., the number of PoDs.
Plane 1 Plane 1
+---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ -+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ -+
+-| |--| |--| |--| |--| |--| |--| |--| |-+ | +-| |--| |--| |--| |--| |--| |--| |--| |-+ |
| | O | | O | | O | | O | | O | | O | | O | | O | | | | | O | | O | | O | | O | | O | | O | | O | | O | | |
+-| |--| |--| |--| |--| |--| |--| |--| |-+ | +-| |--| |--| |--| |--| |--| |--| |--| |-+ |
+---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ | +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ |
----------- . ------------------- . ------------ . ------- | ----------- . ------------------- . ------------ . ------- |
Plane 2 | Plane 2 |
+---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ | +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ |
skipping to change at page 31, line 8 skipping to change at line 1322
| | | |
| ---------------- ------------- | | ---------------- ------------- |
+----- ToF Node Class of PoDs ---+ +----- ToF Node Class of PoDs ---+
---------------- ------------- ---------------- -------------
Figure 12: Northern View of a Maximally Partitioned ToF Level, R=1 Figure 12: Northern View of a Maximally Partitioned ToF Level, R=1
5.3. Fallen Leaf Problem 5.3. Fallen Leaf Problem
As mentioned earlier, RIFT exhibits an anisotropic behavior tailored As mentioned earlier, RIFT exhibits an anisotropic behavior tailored
for fabrics with a North / South orientation and a high level of for fabrics with a north-south orientation and a high level of
interleaving paths. A non-partitioned fabric makes a total loss of interleaving paths. A non-partitioned fabric makes a total loss of
connectivity between a ToF node at the north and a leaf node at the connectivity between a ToF node at the north and a leaf node at the
south a very rare but yet possible occasion that is fully healed by south a very rare but possible occasion that is fully healed by
positive disaggregation as described in Section 6.5.1. In large positive disaggregation as described in Section 6.5.1. In large
fabrics or fabrics built from switches with low radix, the ToF may fabrics or fabrics built from switches with a low radix, the ToF may
often become partitioned in planes which makes the occurrence of often become partitioned in planes, which makes it more likely that a
having a given leaf being only reachable from a subset of the ToF given leaf is only reachable from a subset of the ToF nodes. This
nodes more likely to happen. This makes some further considerations makes some further considerations necessary.
necessary.
A "Fallen Leaf" is a leaf that can be reached by only a subset of ToF A "Fallen Leaf" is a leaf that can be reached by only a subset of ToF
nodes due to missing connectivity. If R is the redundancy factor, nodes due to missing connectivity. If R is the redundancy factor,
then it takes at least R breakages to reach a "Fallen Leaf" then it takes at least R breakages to reach a "Fallen Leaf"
situation. situation.
In a maximally partitioned fabric, the redundancy factor is R=1, so In a maximally partitioned fabric, the redundancy factor is R=1, so
any breakage in the fabric will cause one or more fallen leaves in any breakage in the fabric will cause one or more fallen leaves in
the affected plane. R=2 guarantees that a single breakage will not the affected plane. R=2 guarantees that a single breakage will not
cause a fallen leaf. However, not all cases require disaggregation. cause a fallen leaf. However, not all cases require disaggregation.
The following cases do not require particular action: The following cases do not require particular action:
If a southern link on a node goes down, then connectivity through * If a southern link on a node goes down, then connectivity through
that node is lost for all nodes south of it. There is no need to that node is lost for all nodes south of it. There is no need to
disaggregate since the connectivity to this node is lost for all disaggregate since the connectivity to this node is lost for all
spine nodes in a same fashion. spine nodes in the same fashion.
If a ToF Node goes down, then northern traffic towards it is * If a ToF node goes down, then northern traffic towards it is
routed via alternate ToF nodes in the same plane and there is no routed via alternate ToF nodes in the same plane and there is no
need to disaggregate routes. need to disaggregate routes.
In a general manner, the mechanism of non-transitive positive In a general manner, the mechanism of non-transitive, positive
disaggregation is sufficient when the disaggregating ToF nodes disaggregation is sufficient when the disaggregating ToF nodes
collectively connect to all the ToP nodes in the broken plane. This collectively connect to all the ToP nodes in the broken plane. This
happens in the following case: happens in the following case:
If the breakage is the last northern link from a ToP node to a ToF * If the breakage is the last northern link from a ToP node to a ToF
node going down, then the fallen leaf problem affects only that node going down, then the fallen leaf problem affects only that
ToF node, and the connectivity to all the nodes in the PoD is lost ToF node, and the connectivity to all the nodes in the PoD is lost
from that ToF node. This can be observed by other ToF nodes from that ToF node. This can be observed by other ToF nodes
within the plane where the ToP node is located and positively within the plane where the ToP node is located and positively
disaggregated within that plane. disaggregated within that plane.
On the other hand, there is a need to disaggregate the routes to On the other hand, there is a need to disaggregate the routes to
Fallen Leaves within the plane in a transitive fashion, that is, all Fallen Leaves within the plane in a transitive fashion, that is, all
the way to the other leaves, in the following cases: the way to the other leaves, in the following cases:
* If the breakage is the last northern link from a leaf node within * If the breakage is the last northern link from a leaf node within
a plane (there is only one such link in a maximally partitioned a plane (there is only one such link in a maximally partitioned
fabric) that goes down, then connectivity to all unicast prefixes fabric) that goes down, then connectivity to all unicast prefixes
attached to the leaf node is lost within the plane where the link attached to the leaf node is lost within the plane where the link
is located. Southern Reflection by a leaf node, e.g., between ToP is located. Southern Reflection by a leaf node, e.g., between ToP
nodes, if the PoD has only 2 levels, happens in between planes, nodes, if the PoD has only 2 levels, happens in between planes,
allowing the ToP nodes to detect the problem within the PoD where allowing the ToP nodes to detect the problem within the PoD where
it occurs and positively disaggregate. The breakage can be it occurs and positively disaggregate. The breakage can be
observed by the ToF nodes in the same plane through the North observed by the ToF nodes in the same plane through the north
flooding of TIEs from the ToP nodes. The ToF nodes however need flooding of TIEs from the ToP nodes However, the ToF nodes need to
to be aware of all the affected prefixes for the negative, be aware of all the affected prefixes for the negative, possibly
possibly transitive disaggregation to be fully effective (i.e., a transitive, disaggregation to be fully effective (i.e., a node
node advertising in the control plane that it cannot reach a advertising in the control plane that it cannot reach a certain
certain more specific prefix than default whereas such more specific prefix than default, whereas such disaggregation in
disaggregation must in the extreme condition propagate further the extreme condition must be propagated further down southbound).
down southbound). The problem can also be observed by the ToF The problem can also be observed by the ToF nodes in the other
nodes in the other planes through the flooding of North TIEs from planes through the flooding of North TIEs from the affected leaf
the affected leaf nodes, together with non-node North TIEs which nodes, together with non-node North TIEs, which indicate the
indicate the affected prefixes. To be effective in that case, the affected prefixes. To be effective in that case, the positive
positive disaggregation must reach down to the nodes that make the disaggregation must reach down to the nodes that make the plane
plane selection, which are typically the ingress leaf nodes. The selection, which are typically the ingress leaf nodes. The
information is not useful for routing in the intermediate levels. information is not useful for routing in the intermediate levels.
* If the breakage is a ToP node in a maximally partitioned fabric * If the breakage is a ToP node in a maximally partitioned fabric
(in which case it is the only ToP node serving the plane in that (in which case it is the only ToP node serving the plane in that
PoD that goes down), then the connectivity to all the nodes in the PoD that goes down), then the connectivity to all the nodes in the
PoD is lost within the plane where the ToP node is located. PoD is lost within the plane where the ToP node is located.
Consequently, all leaves of the PoD fall in this plane. Since the Consequently, all leaves of the PoD fall in this plane. Since the
Southern Reflection between the ToF nodes happens only within a Southern Reflection between the ToF nodes happens only within a
plane, ToF nodes in other planes cannot discover fallen leaves in plane, ToF nodes in other planes cannot discover fallen leaves in
a different plane. They also cannot determine beyond their local a different plane. They also cannot determine beyond their local
plane whether a leaf node that was initially reachable has become plane whether a leaf node that was initially reachable has become
unreachable. As the breakage can be observed by the ToF nodes in unreachable. As the breakage can be observed by the ToF nodes in
the plane where the breakage happened, the ToF nodes in the plane the plane where the breakage happened, the ToF nodes in the plane
need to be aware of all the affected prefixes for the negative need to be aware of all the affected prefixes for the negative
disaggregation to be fully effective. The problem can also be disaggregation to be fully effective. The problem can also be
observed by the ToF nodes in the other planes through the flooding observed by the ToF nodes in the other planes through the flooding
of North TIEs from the affected leaf nodes, if there are only 3 of North TIEs from the affected leaf nodes if the failing ToP node
levels and the ToP nodes are directly connected to the leaf nodes, is directly connected to its leaf nodes, which can detect the link
and then again it can only be effective if it is propagated going down. Then again, the knowledge of the failure at the ToF
transitively to the leaf, and useless above that level. level can only be useful if it is propagated transitively to all
the leaves; it is useless above that level since the decision of
placing a packet in a plane happens at the leaf that injects the
packet in the fabric.
These abstractions are rolled back into a simplified example that These abstractions are rolled back into a simplified example that
shows that in Figure 3 the loss of link between spine node 3 and leaf shows that in Figure 3 the loss of the link between spine node 3 and
node 3 will make leaf node 3 a fallen leaf for ToF nodes in plane C. leaf node 3 will make leaf node 3 a fallen leaf for ToF nodes in
Worse, if the cabling was never present in the first place, plane C plane C. Worse, if the cabling was never present in the first place,
will not even be able to know that such a fallen leaf exists. Hence plane C will not even be able to know that such a fallen leaf exists.
partitioning without further treatment results in two grave problems: Hence, partitioning without further treatment results in two grave
problems:
* Leaf node 1 trying to route to leaf node 3 must not choose spine 1. Leaf node 1 trying to route to leaf node 3 must not choose spine
node 3 in plane C as its next hop since it will inevitably drop node 3 in plane C as its next hop since it will inevitably drop
the packet when forwarding using default routes or do excessive the packet when forwarding using default routes or do excessive
bow-tying. This information must be in its routing table. bow-tying. This information must be in its routing table.
* A path computation trying to deal with the problem by distributing 2. A path computation trying to deal with the problem by
host routes may only form paths through leaves. The flooding of distributing host routes may only form paths through leaves. The
information about leaf node 3 would have to go up to ToF nodes in flooding of information about leaf node 3 would have to go up to
planes A, B, and D and then "loopback" over other leaves to ToF C ToF nodes in planes A, B, and D and then "loopback" over other
leading in extreme cases to traffic for leaf node 3 when presented leaves to ToF C, leading in extreme cases to traffic for leaf
to plane C taking an "inverted fabric" path where leaves start to node 3 when presented to plane C taking an "inverted fabric" path
serve as ToFs, at least for the duration of a protocol's where leaves start to serve as ToFs, at least for the duration of
convergence. a protocol's convergence.
5.4. Discovering Fallen Leaves 5.4. Discovering Fallen Leaves
When aggregation is used, RIFT deals with fallen leaves by ensuring When aggregation is used, RIFT deals with fallen leaves by ensuring
that all the ToF nodes share the same north topology database. This that all the ToF nodes share the same north topology database. This
happens naturally in single plane design by the means of northbound happens naturally in single-plane design by the means of northbound
flooding and south reflection but needs additional considerations in flooding and south reflection but needs additional considerations in
multi-plane fabrics. To enable routing to fallen leaves in multi- multi-plane fabrics. To enable routing to fallen leaves in multi-
plane designs, RIFT requires additional interconnection across planes plane designs, RIFT requires additional interconnection across planes
between the ToF nodes, e.g., using rings as illustrated in Figure 13. between the ToF nodes, e.g., using rings as illustrated in Figure 13.
Other solutions are possible but they either need more cabling or end Other solutions are possible, but they either need more cabling or
up having much longer flooding paths and/or single points of failure. end up having much longer flooding paths and/or single points of
failure.
In detail, by reserving at least two ports on each ToF node it is In detail, by reserving at least two ports on each ToF node, it is
possible to connect them together by interplane bi-directional rings possible to connect them together by interplane bidirectional rings
as illustrated in Figure 13. The rings will be used to exchange full as illustrated in Figure 13. The rings will be used to exchange full
north topology information between planes. All ToFs having the same north topology information between planes. All ToFs having the same
north topology allows by the means of transitive, negative north topology allows, by the means of transitive, negative
disaggregation described in Section 6.5.2 to efficiently fix any disaggregation described in Section 6.5.2, to efficiently fix any
possible fallen leaf scenario. Somewhat as a side effect, the possible fallen leaf scenario. Somewhat as a side effect, the
exchange of information fulfills the requirement for a full view of exchange of information fulfills the requirement for a full view of
the fabric topology at the ToF level, without the need to collate it the fabric topology at the ToF level without the need to collate it
from multiple points. from multiple points.
____________________________________________________________________________ ____________________________________________________________________________
| [Plane A] . [Plane B] . [Plane C] . [Plane D] | | [Plane A] . [Plane B] . [Plane C] . [Plane D] |
|..........................................................................| |..........................................................................|
| +-------------------------------------------------------------+ | | +-------------------------------------------------------------+ |
| | +---+ . +---+ . +---+ . +---+ | | | | +---+ . +---+ . +---+ . +---+ | |
| +-+ n +-------------+ n +-------------+ n +-------------+ n +-+ | | +-+ n +-------------+ n +-------------+ n +-------------+ n +-+ |
| +--++ . +-+++ . +-+++ . +--++ | | +--++ . +-+++ . +-+++ . +--++ |
| || . || . || . || | | || . || . || . || |
| +---------||---------------||----------------||---------------+ || | | +---------||---------------||----------------||---------------+ || |
| | +---+ || . +---+ || . +---+ || . +---+ | || | | | +---+ || . +---+ || . +---+ || . +---+ | || |
| +-+ 1 +---||--------+ 1 +--||---------+ 1 +--||---------+ 1 +-+ || | | +-+ 1 +---||--------+ 1 +--||---------+ 1 +--||---------+ 1 +-+ || |
| +--++ || . +-+++ || . +-+++ || . +-+++ || | | +--++ || . +-+++ || . +-+++ || . +-+++ || |
| || || . || || . || || . || || | | || || . || || . || || . || || |
| || || . || || . || || . || || | | || || . || || . || || . || || |
Figure 13: Using rings to bring all planes and at the ToF bind them Figure 13: Using Rings to Bring All Planes and Bind Them at the ToF
5.5. Addressing the Fallen Leaves Problem 5.5. Addressing the Fallen Leaves Problem
One consequence of the "Fallen Leaf" problem is that some prefixes One consequence of the "Fallen Leaf" problem is that some prefixes
attached to the fallen leaf become unreachable from some of the ToF attached to the fallen leaf become unreachable from some of the ToF
nodes. RIFT defines two methods to address this issue denoted as nodes. RIFT defines two methods to address this issue, denoted as
positive disaggregation and negative disaggregation. Both methods positive disaggregation and negative disaggregation. Both methods
flood corresponding types of South TIEs to advertise the impacted flood corresponding types of South TIEs to advertise the impacted
prefix(es). prefix(es).
When used for the operation of disaggregation, a positive South TIE, When used for the operation of disaggregation, a positive South TIE,
as usual, indicates reachability to a prefix of given length and all as usual, indicates reachability to a prefix of given length and all
addresses subsumed by it. In contrast, a negative route addresses subsumed by it. In contrast, a negative route
advertisement indicates that the origin cannot route to the advertisement indicates that the origin cannot route to the
advertised prefix. advertised prefix.
The positive disaggregation is originated by a router that can still The positive disaggregation is originated by a router that can still
reach the advertised prefix, and the operation is not transitive. In reach the advertised prefix, and the operation is not transitive. In
other words, the receiver does *not* generate its own TIEs or flood other words, the receiver does *not* generate its own TIEs or flood
them south as a consequence of receiving positive disaggregation them south as a consequence of receiving positive disaggregation
advertisements from a higher level node. The effect of a positive advertisements from a higher-level node. The effect of a positive
disaggregation is that the traffic to the impacted prefix will follow disaggregation is that the traffic to the impacted prefix will follow
the longest match and will be limited to the northbound routers that the longest match and will be limited to the northbound routers that
advertised the more specific route. advertised the more specific route.
In contrast, the negative disaggregation can be transitive, and is In contrast, the negative disaggregation can be transitive and is
propagated south when all the possible routes have been advertised as propagated south when all the possible routes have been advertised as
negative exceptions. A negative route advertisement is only negative exceptions. A negative route advertisement is only
actionable when the negative prefix is aggregated by a positive route actionable when the negative prefix is aggregated by a positive route
advertisement for a shorter prefix. In such case, the negative advertisement for a shorter prefix. In such case, the negative
advertisement "punches out a hole" in the positive route in the advertisement "punches out a hole" in the positive route in the
routing table, making the positive prefix reachable through the routing table, making the positive prefix reachable through the
originator with the special consideration of the negative prefix originator with the special consideration of the negative prefix
removing certain next hop neighbors. The specific procedures will be removing certain next-hop neighbors. The specific procedures are
explained in detail in Section 6.5.2.3. explained in detail in Section 6.5.2.3.
When the ToF switches are not partitioned into multiple planes, the When the ToF switches are not partitioned into multiple planes, the
resulting southbound flooding of the positive disaggregation by the resulting southbound flooding of the positive disaggregation by the
ToF nodes that can still reach the impacted prefix is in general ToF nodes that can still reach the impacted prefix is generally
enough to cover all the switches at the next level south, typically enough to cover all the switches at the next level south, typically
the ToP nodes. If all those switches are aware of the the ToP nodes. If all those switches are aware of the
disaggregation, they collectively create a ceiling that intercepts disaggregation, they collectively create a ceiling that intercepts
all the traffic north and forwards it to the ToF nodes that all the traffic north and forwards it to the ToF nodes that
advertised the more specific route. In that case, the positive advertised the more specific route. In that case, the positive
disaggregation alone is sufficient to solve the fallen leaf problem. disaggregation alone is sufficient to solve the fallen leaf problem.
On the other hand, when the fabric is partitioned in planes, the On the other hand, when the fabric is partitioned in planes, the
positive disaggregation from ToF nodes in different planes do not positive disaggregation from ToF nodes in different planes do not
reach the ToP switches in the affected plane and cannot solve the reach the ToP switches in the affected plane and cannot solve the
skipping to change at page 35, line 33 skipping to change at line 1536
packet typically occurs at the leaf level and the disaggregation must packet typically occurs at the leaf level and the disaggregation must
be transitive and reach all the leaves. In that case, the negative be transitive and reach all the leaves. In that case, the negative
disaggregation is necessary. The details on the RIFT approach to disaggregation is necessary. The details on the RIFT approach to
deal with fallen leaves in an optimal way are specified in deal with fallen leaves in an optimal way are specified in
Section 6.5.2. Section 6.5.2.
6. Specification 6. Specification
This section specifies the protocol in a normative fashion by either This section specifies the protocol in a normative fashion by either
prescriptive procedures or behavior defined by Finite State Machines prescriptive procedures or behavior defined by Finite State Machines
(FSM). (FSMs).
The FSMs, as usual, are presented as states a neighbor can assume, The FSMs, as usual, are presented as states a neighbor can assume,
events that can occur, and the corresponding actions performed when events that can occur, and the corresponding actions performed when
transitioning between states on event processing. transitioning between states on event processing.
Actions are performed before the end state is assumed. Actions are performed before the end state is assumed.
The FSMs can queue events against itself to chain actions or against The FSMs can queue events against themselves to chain actions or
other FSMs in the specification. Events are always processed in the against other FSMs in the specification. Events are always processed
sequence they have been queued. in the sequence they have been queued.
Consequently, "On Entry" actions for an FSM state are performed every Consequently, "On Entry" actions for an FSM state are performed every
time and right before the corresponding state is entered, i.e., after time and right before the corresponding state is entered, i.e., after
any transitions from previous state. any transitions from previous state.
"On Exit" actions are performed every time and immediately when a "On Exit" actions are performed every time and immediately when a
state is exited, i.e., before any transitions towards target state state is exited, i.e., before any transitions towards the target
are performed. state are performed.
Any attempt to transition from a state towards another on reception Any attempt to transition from a state towards another on reception
of an event where no action is specified MUST be considered an of an event where no action is specified MUST be considered an
unrecoverable error and the protocol MUST reset all adjacencies and unrecoverable error, and the protocol MUST reset all adjacencies and
discard all the state (i.e., force the FSM back to _OneWay_ and flush discard all the states (i.e., force the FSM back to _OneWay_ and
all of the queues holding flooding information). flush all of the queues holding flooding information).
The data structures and FSMs described in this document are The data structures and FSMs described in this document are
conceptual and do not have to be implemented precisely as described conceptual and do not have to be implemented precisely as described
here, i.e., an implementation is considered conforming as long as it here, i.e., an implementation is considered conforming as long as it
supports the described functionality and exhibits externally supports the described functionality and exhibits externally
observable behavior equivalent to the behavior of the standardized observable behavior equivalent to the behavior of the standardized
FSMs. FSMs.
The FSMs can use "timers" for different situations. Those timers are The FSMs can use "timers" for different situations. Those timers are
started through actions and their expiration leads to queuing of started through actions, and their expiration leads to queuing of
corresponding events to be processed. corresponding events to be processed.
The term "holdtime" is used often as short-hand for "holddown timer" The term "holdtime" is used often as shorthand for "holddown timer"
and signifies either the length of the holding down period or the and signifies either the length of the holding down period or the
timer used to expire after such period. Such timers are used to timer used to expire after such period. Such timers are used to
"hold down" state within an FSM that is cleaned if the machine "hold down" the state within an FSM that is cleaned if the machine
triggers a _HoldtimeExpired_ event. triggers a _HoldtimeExpired_ event.
6.1. Transport 6.1. Transport
All normative RIFT packet structures and their contents are defined All normative RIFT packet structures and their contents are defined
in the Thrift [thrift] models in Section 7. The packet structure in the Thrift [thrift] models in Section 7. The packet structure
itself is defined in _ProtocolPacket_ which contains the packet itself is defined in _ProtocolPacket_, which contains the packet
header in _PacketHeader_ and the packet contents in _PacketContent_. header in _PacketHeader_ and the packet contents in _PacketContent_.
_PacketContent_ is a union of the LIE, TIE, TIDE, and TIRE packets _PacketContent_ is a union of the LIE, TIE, TIDE, and TIRE packets,
which are subsequently defined in _LIEPacket_, _TIEPacket_, which are subsequently defined in _LIEPacket_, _TIEPacket_,
_TIDEPacket_, and _TIREPacket_ respectively. _TIDEPacket_, and _TIREPacket_, respectively.
Further, in terms of bits on the wire, it is the _ProtocolPacket_ Further, in terms of bits on the wire, it is the _ProtocolPacket_
that is serialized and carried in an envelope defined in that is serialized and carried in an envelope defined in
Section 6.9.3 within a UDP frame that provides security and allows Section 6.9.3 within a UDP frame that provides security and allows
validation/modification of several important fields without Thrift validation/modification of several important fields without Thrift
de-serialization for performance and security reasons. Security deserialization for performance and security reasons. Security
model and procedures are further explained in Section 9. models and procedures are further explained in Section 9.
6.2. Link (Neighbor) Discovery (LIE Exchange) 6.2. Link (Neighbor) Discovery (LIE Exchange)
RIFT LIE exchange auto-discovers neighbors, negotiates RIFT ZTP RIFT LIE exchange auto-discovers neighbors, negotiates RIFT ZTP
parameters and discovers miscablings. The formation progresses under parameters, and discovers miscablings. The formation progresses
normal conditions from _OneWay_ to _TwoWay_ and then _ThreeWay_ state under normal conditions from _OneWay_ to _TwoWay_ and then _ThreeWay_
at which point it is ready to exchange TIEs per Section 6.3. The state, at which point it is ready to exchange TIEs as described in
adjacency exchanges RIFT ZTP information (Section 6.7) in any of the Section 6.3. The adjacency exchanges RIFT ZTP information
states, i.e. it is not necessary to reach _ThreeWay_ for zero-touch (Section 6.7) in any of the states, i.e., it is not necessary to
provisioning to operate. reach _ThreeWay_ for ZTP to operate.
RIFT supports any combination of IPv4 and IPv6 addressing, including RIFT supports any combination of IPv4 and IPv6 addressing, including
link-local scope, on the fabric to form adjacencies with the link-local scope, on the fabric to form adjacencies with the
additional capability for forwarding paths that are capable of additional capability for forwarding paths that are capable of
forwarding IPv4 packets in presence of IPv6 addressing only. forwarding IPv4 packets in the presence of IPv6 addressing only.
IPv4 LIE exchange happens by default over well-known administratively IPv4 LIE exchange happens by default over well-known administratively
locally scoped and configured or otherwise well-known IPv4 multicast locally scoped and configured or otherwise well-known IPv4 multicast
address [RFC2365]. For IPv6 [RFC8200] exchange is performed over address [RFC2365]. For IPv6 [RFC8200], exchange is performed over
link-local multicast scope [RFC4291] address which is configured or the link-local multicast scope [RFC4291] address, which is configured
otherwise well-known. In both cases a destination UDP port defined or otherwise well-known. In both cases, a destination UDP port
in the schema Section 7.2 is used unless configured otherwise. LIEs defined in the schema (Section 7.2) is used unless configured
MUST be sent with an IPv4 Time to Live (TTL) or an IPv6 Hop Limit otherwise. LIEs MUST be sent with an IPv4 Time to Live (TTL) or an
(HL) of either 1 or 255 to prevent RIFT information reaching beyond a IPv6 Hop Limit (HL) of either 1 or 255 to prevent RIFT information
single L3 next-hop in the topology. Observe that for the allocated reaching beyond a single Layer 3 (L3) next hop in the topology.
link-local scope IP multicast address TTL value of 1 is a more Observe that, for the allocated link-local scope IP multicast
logical choice since TTL value of 255 may in some environment lead to address, the TTL value of 1 is a more logical choice since the TTL
an early drop due to suspicious TTL value for a packet addressed to value of 255 may, in some environments, lead to an early drop due to
such destination. LIEs SHOULD be sent with network control the suspicious TTL value for a packet addressed to such a
precedence unless an implementation is prevented from doing so destination. LIEs SHOULD be sent with network control precedence
[RFC2474]. unless an implementation is prevented from doing so [RFC2474].
Any LIE packet received on an address that is neither the well-known Any LIE packet received on an address that is neither the well-known
nor configured multicast or a broadcast address MUST be discarded. nor configured multicast or a broadcast address MUST be discarded.
The originating port of the LIE has no further significance other The originating port of the LIE has no further significance, other
than identifying the origination point. LIEs are exchanged over all than identifying the origination point. LIEs are exchanged over all
links running RIFT. links running RIFT.
An implementation may listen and send LIEs on IPv4 and/or IPv6 An implementation may listen and send LIEs on IPv4 and/or IPv6
multicast addresses. A node MUST NOT originate LIEs on an address multicast addresses. A node MUST NOT originate LIEs on an address
family if it does not process received LIEs on that family. LIEs on family if it does not process received LIEs on that family. LIEs on
the same link are considered part of the same LIE FSM independent of the same link are considered part of the same LIE FSM independent of
the address family they arrive on. The LIE source address may not the address family they arrive on. The LIE source address may not
identify the peer uniquely in unnumbered or link-local address cases identify the peer uniquely in unnumbered or link-local address cases
so the response transmission MUST occur over the same interface the so the response transmission MUST occur over the same interface the
LIEs have been received on. A node may use any of the adjacency's LIEs have been received on. A node may use any of the adjacency's
source addresses it saw in LIEs on the specific interface during source addresses it saw in LIEs on the specific interface during
adjacency formation to send TIEs (Section 6.3.3). That implies that adjacency formation to send TIEs (Section 6.3.3). That implies that
an implementation MUST be ready to accept TIEs on all addresses it an implementation MUST be ready to accept TIEs on all addresses it
used as source of LIE frames. used as sources of LIE frames.
A simplified version MAY be implemented on platforms with limited A simplified version MAY be implemented on platforms with limited
multicast support (e.g. IoT devices) by sending and receiving LIE multicast support (e.g., Internet of Things (IoT) devices) by sending
frames on IPv4 subnet broadcast addresses or IPv6 all routers and receiving LIE frames on IPv4 subnet broadcast addresses or IPv6
multicast address. However, this technique is less optimal and all-routers multicast addresses. However, this technique is less
presents a wider attack surface from a security perspective and optimal and presents a wider attack surface from a security
should hence be used only as last resort. perspective and should hence be used only as a last resort.
A _ThreeWay_ adjacency (as defined in the glossary) over any address A _ThreeWay_ adjacency (as defined in the glossary) over any address
family implies support for IPv4 forwarding if the family implies support for IPv4 forwarding if the
_ipv4_forwarding_capable_ flag in _LinkCapabilities_ is set to true. _ipv4_forwarding_capable_ flag in _LinkCapabilities_ is set to true.
In the absence of IPv4 LIEs with _ipv4_forwarding_capable_ set to In the absence of IPv4 LIEs with _ipv4_forwarding_capable_ set to
true, a node MUST forward IPv4 packets using gateways discovered on true, a node MUST forward IPv4 packets using gateways discovered on
IPv6-only links advertising this capability. The mechanism to IPv6-only links advertising this capability. The mechanism to
discover the corresponding IPv6 gateway is out of scope for this discover the corresponding IPv6 gateway is out of scope for this
specification and may be implementation specific. It is expected specification and may be implementation-specific. It is expected
that the whole fabric supports the same type of forwarding of address that the whole fabric supports the same type of forwarding of address
families on all the links, any other combination is outside the scope families on all the links; any other combination is outside the scope
of this specification. If IPv4 forwarding is supported on an of this specification. If IPv4 forwarding is supported on an
interface, _ipv4_forwarding_capable_ MUST be set to true for all LIEs interface, _ipv4_forwarding_capable_ MUST be set to true for all LIEs
advertised from that interface. If IPv4 and IPv6 LIEs indicate advertised from that interface. If IPv4 and IPv6 LIEs indicate
contradicting information, protocol behavior is unspecified. A node contradicting information, protocol behavior is unspecified. A node
sending IPv4 LIEs MUST set the _ipv4_forwarding_capable_ flag to true sending IPv4 LIEs MUST set the _ipv4_forwarding_capable_ flag to true
on all LIEs advertised from that interface. on all LIEs advertised from that interface.
Operation of a fabric where only some of the links are supporting Operation of a fabric where only some of the links are supporting
forwarding on an address family or have an address in a family and forwarding on an address family or have an address in a family and
others do not is outside the scope of this specification. others do not is outside the scope of this specification.
Any attempt to construct IPv6 forwarding over IPv4 only adjacencies Any attempt to construct IPv6 forwarding over IPv4-only adjacencies
is outside this specification. is outside the scope of this specification.
Table 1 outlines protocol behavior pertaining to LIE exchange over Table 1 outlines protocol behavior pertaining to LIE exchange over
different address family combinations. Table 2 outlines the way in different address family combinations. Table 2 outlines the way in
which neighbors forward traffic as it pertains to the which neighbors forward traffic as it pertains to the
_ipv4_forwarding_capable_ flag setting across the same address family _ipv4_forwarding_capable_ flag setting across the same address family
combinations. The table is symmetric, i.e. local and remote can be combinations. The table is symmetric, i.e., the local and remote
exchanged to construct the remaining combinations. columns can be exchanged to construct the remaining combinations.
The specific forwarding implementation to support the described The specific forwarding implementation to support the described
behavior is out of scope for this document. behavior is out of scope for this document.
+==========+==========+==========================================+ +==========+==========+==========================================+
| Local | Remote | LIE Exchange Behavior | | Local | Remote | LIE Exchange Behavior |
| Neighbor | Neighbor | | | Neighbor | Neighbor | |
| AF | AF | | | AF | AF | |
+==========+==========+==========================================+ +==========+==========+==========================================+
| IPv4 | IPv4 | LIEs and TIEs are exchanged over IPv4 | | IPv4 | IPv4 | LIEs and TIEs are exchanged over IPv4 |
| | | only. The local neighbor receives TIEs | | | | only. The local neighbor receives TIEs |
| | | from remote neighbors on any of the LIE | | | | from remote neighbors on any of the LIE |
| | | source addresses. | | | | source addresses. |
+----------+----------+------------------------------------------+ +----------+----------+------------------------------------------+
| IPv6 | IPv6 | LIEs and TIEs are exchanged over IPv6 | | IPv6 | IPv6 | LIEs and TIEs are exchanged over IPv6 |
| | | only. The local neighbor receives TIEs | | | | only. The local neighbor receives TIEs |
| | | from remote neighbors on any of the LIE | | | | from remote neighbors on any of the LIE |
| | | source addresses. | | | | source addresses. |
+----------+----------+------------------------------------------+ +----------+----------+------------------------------------------+
| IPv4, | IPv6 | The local neighbor sends LIEs for both | | IPv4, | IPv6 | The local neighbor sends LIEs for both |
| IPv6 | | IPv4 and IPv6 while the remote neighbor | | IPv6 | | IPv4 and IPv6, while the remote neighbor |
| | | only sends LIEs for IPv6. The resulting | | | | only sends LIEs for IPv6. The resulting |
| | | adjacency will exchange TIEs over IPv6 | | | | adjacency will exchange TIEs over IPv6 |
| | | on any of the IPv6 LIE source addresses. | | | | on any of the IPv6 LIE source addresses. |
+----------+----------+------------------------------------------+ +----------+----------+------------------------------------------+
| IPv4, | IPv4, | LIEs and TIEs are exchanged over IPv6 | | IPv4, | IPv4, | LIEs and TIEs are exchanged over IPv6 |
| IPv6 | IPv6 | and IPv4. TIEs are received on any of | | IPv6 | IPv6 | and IPv4. TIEs are received on any of |
| | | the IPv4 or IPv6 LIE source addresses. | | | | the IPv4 or IPv6 LIE source addresses. |
| | | The local neighbor receives TIEs from | | | | The local neighbor receives TIEs from |
| | | the remote neighbors on any of the IPv4 | | | | the remote neighbors on any of the IPv4 |
| | | or IPv6 LIE source addresses. | | | | or IPv6 LIE source addresses. |
+----------+----------+------------------------------------------+ +----------+----------+------------------------------------------+
| IPv4, | IPv4 | The local neighbor sends LIEs for both | | IPv4, | IPv4 | The local neighbor sends LIEs for both |
| IPv6 | | IPv4 and IPv6 while the remote neighbor | | IPv6 | | IPv4 and IPv6, while the remote neighbor |
| | | only sends LIEs for IPv4. The resulting | | | | only sends LIEs for IPv4. The resulting |
| | | adjacency will exchange TIEs over IPv4 | | | | adjacency will exchange TIEs over IPv4 |
| | | on any of the IPv4 LIE source addresses. | | | | on any of the IPv4 LIE source addresses. |
+----------+----------+------------------------------------------+ +----------+----------+------------------------------------------+
Table 1: Control Plane Behavior for Neighbor AF Combinations Table 1: Control Plane Behavior for Neighbor AF Combinations
+==========+==========+==========================================+ +==========+==========+==========================================+
| Local | Remote | Forwarding Behavior | | Local | Remote | Forwarding Behavior |
| Neighbor | Neighbor | | | Neighbor | Neighbor | |
skipping to change at page 40, line 39 skipping to change at line 1759
| | | flags, the behavior is unspecified. | | | | flags, the behavior is unspecified. |
+----------+----------+------------------------------------------+ +----------+----------+------------------------------------------+
| IPv4, | IPv4 | IPv4 traffic can be forwarded. | | IPv4, | IPv4 | IPv4 traffic can be forwarded. |
| IPv6 | | | | IPv6 | | |
+----------+----------+------------------------------------------+ +----------+----------+------------------------------------------+
Table 2: Forwarding Behavior for Neighbor AF Combinations Table 2: Forwarding Behavior for Neighbor AF Combinations
The protocol does *not* support selective disabling of address The protocol does *not* support selective disabling of address
families after adjacency formation, disabling IPv4 forwarding families after adjacency formation, disabling IPv4 forwarding
capability or any local address changes in _ThreeWay_ state, i.e. if capability, or any local address changes in _ThreeWay_ state, i.e.,
a link has entered ThreeWay IPv4 and/or IPv6 with a neighbor on an if a link has entered ThreeWay IPv4 and/or IPv6 with a neighbor on an
adjacency and it wants to stop supporting one of the families or adjacency and it wants to stop supporting one of the families, change
change any of its local addresses or stop IPv4 forwarding, it MUST any of its local addresses, or stop IPv4 forwarding, it MUST tear
tear down and rebuild the adjacency. It MUST also remove any state down and rebuild the adjacency. It MUST also remove any state it
it stored about the remote side of the adjacency such as associated stored about the remote side of the adjacency such as associated LIE
LIE source addresses. source addresses.
Unless RIFT ZTP as described in Section 6.7 is used, each node is Unless RIFT ZTP is used as described in Section 6.7, each node is
provisioned with the level at which it is operating and advertises it provisioned with the level at which it is operating and advertises it
in the _level_ of the _PacketHeader_ schema element. It MAY be also in the _level_ of the _PacketHeader_ schema element. It MAY also be
provisioned with its PoD. If level is not provisioned, it is not provisioned with its PoD. If the level is not provisioned, it is not
present in the optional _PacketHeader_ schema element and established present in the optional _PacketHeader_ schema element and established
by ZTP procedures if feasible. If PoD is not provisioned, it is by ZTP procedures, if feasible. If PoD is not provisioned, it is
governed by the _LIEPacket_ schema element assuming the governed by the _LIEPacket_ schema element assuming the
_common.default_pod_ value. This means that switches except ToF do _common.default_pod_ value. This means that switches except ToF do
not need to be configured at all. Necessary information to configure not need to be configured at all. Necessary information to configure
all values is exchanged in the _LIEPacket_ and _PacketHeader_ or all values is exchanged in the _LIEPacket_ and _PacketHeader_ or
derived by the node automatically. derived by the node automatically.
Further definitions of leaf flags are found in Section 6.7 given they Further definitions of leaf flags are found in Section 6.7 given they
have implications in terms of level and adjacency forming here. Leaf have implications in terms of level and adjacency forming here. Leaf
flags are carried in _HierarchyIndications_. flags are carried in _HierarchyIndications_.
A node MUST form a _ThreeWay_ adjacency if at a minimum the following A node MUST form a _ThreeWay_ adjacency if, at a minimum, the
first order logic conditions are satisfied on a LIE packet as following first order logic conditions are satisfied on a LIE packet,
specified by the _LIEPacket_ schema element and received on a link as specified by the _LIEPacket_ schema element and received on a link
(such a LIE is considered a "minimally valid" LIE). Observe that (such a LIE is considered a "minimally valid" LIE). Observe that,
depending on the FSM involved and its state further conditions may be depending on the FSM involved and its state further, conditions may
checked and even a minimally valid LIE can be considered ultimately be checked, and even a minimally valid LIE can be considered
invalid if any of the additional conditions fail. ultimately invalid if any of the additional conditions fail:
1. the neighboring node is running the same major schema version as 1. the neighboring node is running the same major schema version as
indicated in the _major_version_ element in _PacketHeader_ *and* indicated in the _major_version_ element in _PacketHeader_;
2. the neighboring node uses a valid System ID (i.e. value different 2. the neighboring node uses a valid System ID (i.e., a value
from _IllegalSystemID_) in the _sender_ element in _PacketHeader_ different from _IllegalSystemID_) in the _sender_ element in
*and* _PacketHeader_;
3. the neighboring node uses a different System ID than the node 3. the neighboring node uses a different System ID than the node
itself *and* itself;
4. (the advertised MTU values in the _LiePacket_ element match on 4. the advertised MTU values in the _LiePacket_ element match on
both sides while a missing MTU in the _LiePacket_ element is both sides, while a missing MTU in the _LiePacket_ element is
interpreted as _default_mtu_size_) *and* interpreted as _default_mtu_size_;
5. both nodes advertise defined level values in _level_ element in 5. both nodes advertise defined level values in the _level_ element
_PacketHeader_ *and* in _PacketHeader_, *and*
6. [ 6. either:
i) the node is at _leaf_level_ value and has no _ThreeWay_ a. the node is at the _leaf_level_ value and has no _ThreeWay_
adjacencies already to nodes at Highest Adjacency _ThreeWay_ adjacencies already to nodes at Highest Adjacency _ThreeWay_
(HAT as defined later in Section 6.7.1) with level different (HAT), as defined later in Section 6.7.1, with the level
than the adjacent node *or* different than the adjacent node;
ii) the node is not at _leaf_level_ value and the neighboring b. the node is not at the _leaf_level_ value and the neighboring
node is at _leaf_level_ value *or* node is at the _leaf_level_ value;
iii) both nodes are at _leaf_level_ values *and* both indicate c. both nodes are at the _leaf_level_ values *and* both indicate
support for Section 6.8.9 *or* support for that described in Section 6.8.9; *or*
iv) neither node is at _leaf_level_ value and the neighboring
node is at most one level difference away
]. d. neither node is at the _leaf_level_ value and the neighboring
node is, at most, one level away.
LIEs arriving with IPv4 Time to Live (TTL) or an IPv6 Hop Limit (HL) LIEs arriving with IPv4 Time to Live (TTL) or an IPv6 Hop Limit (HL)
different than 1 or 255 MUST be ignored. different than 1 or 255 MUST be ignored.
6.2.1. LIE Finite State Machine 6.2.1. LIE Finite State Machine
This section specifies the precise, normative LIE FSM which is given This section specifies the precise, normative LIE FSM, which is also
as well in Figure 14. Additionally, some sets of actions often shown in Figure 14. Additionally, some sets of actions often repeat
repeat and are hence summarized into well-known procedures. and are hence summarized into well-known procedures.
Events generated are fairly fine grained, especially when indicating Events generated are fairly fine grained, especially when indicating
problems in adjacency forming conditions to simplify tracking of problems in adjacency-forming conditions to simplify tracking of
problems in deployment. problems in deployment.
Initial state is _OneWay_. The initial state is _OneWay_.
The machine sends LIEs proactively on several transitions to The machine sends LIEs proactively on several transitions to
accelerate adjacency bring-up without waiting for the corresponding accelerate adjacency bring-up without waiting for the corresponding
timer tic. timer tic.
Enter Enter
| |
V V
+-----------+ +-----------+
| OneWay |<----+ | OneWay |<----+
skipping to change at page 45, line 17 skipping to change at line 1976
| | LevelChanged | | LevelChanged
+------------+ MultipleNeighborsDone +------------+ MultipleNeighborsDone
Figure 14: LIE FSM Figure 14: LIE FSM
The following words are used for well-known procedures: The following words are used for well-known procedures:
* PUSH Event: queues an event to be executed by the FSM upon exit of * PUSH Event: queues an event to be executed by the FSM upon exit of
this action this action
* CLEANUP: The FSM *conceptually* holds a `current neighbor` * CLEANUP: The FSM *conceptually* holds a "current neighbor"
variable that contains information received in the remote node's variable that contains information received in the remote node's
LIE that is processed against LIE validation rules. In the event LIE that is processed against LIE validation rules. In the event
that the LIE is considered to be invalid, the existing state held that the LIE is considered to be invalid, the existing state held
by `current neighbor` MUST be deleted. by a "current neighbor" MUST be deleted.
* SEND_LIE: create and send a new LIE packet * SEND_LIE: create and send a new LIE packet
1. reflecting the _neighbor_ element as described in 1. reflecting the _neighbor_ element as described in
ValidReflection and ValidReflection,
2. setting the necessary _not_a_ztp_offer_ variable if level was 2. setting the necessary _not_a_ztp_offer_ variable if the level
derived from the last known neighbor on this interface and was derived from the last-known neighbor on this interface,
and
3. setting _you_are_flood_repeater_ variable to the computed 3. setting the _you_are_flood_repeater_ variable to the computed
value value.
* PROCESS_LIE: * PROCESS_LIE:
1. if LIE has a major version not equal to this node's major 1. if LIE has a major version not equal to this node's major
version *or* System ID equal to (this node's System ID or version *or* System ID equal to this node's System ID or
_IllegalSystemID_) then CLEANUP else _IllegalSystemID_, then CLEANUP, else
2. if both sides advertise Layer 2 MTU values and the MTU in the 2. if both sides advertise Layer 2 MTU values and the MTU in the
received LIE does not match the MTU advertised by the local received LIE does not match the MTU advertised by the local
system *or* at least one of the nodes does not advertise an system *or* at least one of the nodes does not advertise an
MTU value and the advertising node's LIE does not match the MTU value and the advertising node's LIE does not match the
_default_mtu_size_ of the system not advertising an MTU then _default_mtu_size_ of the system not advertising an MTU, then
CLEANUP, PUSH UpdateZTPOffer, PUSH MTUMismatch else CLEANUP, PUSH UpdateZTPOffer, and PUSH MTUMismatch, else
3. if the LIE has an undefined level *or* this node's level is 3. if the LIE has an undefined level *or* this node's level is
undefined *or* this node is a leaf and remote level is lower undefined *or* this node is a leaf and the remote level is
than HAT *or* (the LIE's level is not leaf *and* its lower than HAT *or* the LIE's level is not leaf *and* its
difference is more than one from this node's level) then difference is more than one from this node's level, then
CLEANUP, PUSH UpdateZTPOffer, PUSH UnacceptableHeader else CLEANUP, PUSH UpdateZTPOffer, and PUSH UnacceptableHeader,
else
4. PUSH UpdateZTPOffer, construct temporary new neighbor 4. PUSH UpdateZTPOffer, construct a temporary new neighbor
structure with values from LIE, if no current neighbor exists structure with values from LIE, if no current neighbor exists,
then set current neighbor to new neighbor, PUSH NewNeighbor then set current neighbor to new neighbor, PUSH NewNeighbor
event, CHECK_THREE_WAY else event, CHECK_THREE_WAY, else
1. if current neighbor System ID differs from LIE's System ID a. if the current neighbor System ID differs from LIE's
then PUSH MultipleNeighbors else System ID, then PUSH MultipleNeighbors, else
2. if current neighbor stored level differs from LIE's level b. if the current neighbor stored level differs from LIE's
then PUSH NeighborChangedLevel else level, then PUSH NeighborChangedLevel, else
3. if current neighbor stored IPv4/v6 address differs from c. if the current neighbor stored IPv4/v6 address differs
LIE's address then PUSH NeighborChangedAddress else from LIE's address, then PUSH NeighborChangedAddress, else
4. if any of neighbor's flood address port, name, or local d. if any of the neighbor's flood address port, name, or
LinkID changed then PUSH NeighborChangedMinorFields local LinkID changed, then PUSH NeighborChangedMinorFields
5. CHECK_THREE_WAY e. CHECK_THREE_WAY
* CHECK_THREE_WAY: if current state is _OneWay_ do nothing else * CHECK_THREE_WAY: if the current state is _OneWay_, do nothing,
else
1. if LIE packet does not contain neighbor then if current state 1. if LIE packet does not contain a neighbor and if the current
is _ThreeWay_ then PUSH NeighborDroppedReflection else state is _ThreeWay_, then PUSH NeighborDroppedReflection, else
2. if packet reflects this system's ID and local port and state 2. if the packet reflects this System ID and local port and the
is _ThreeWay_ then PUSH event ValidReflection else PUSH event state is _ThreeWay_, then PUSH the ValidReflection event, else
MultipleNeighbors PUSH the MultipleNeighbors event.
States: States:
* OneWay: initial state the FSM is starting from. In this state the * OneWay: The initial state the FSM is starting from. In this
router did not receive any valid LIEs from a neighbor. state, the router did not receive any valid LIEs from a neighbor.
* TwoWay: that state is entered when a node has received a minimally * TwoWay: This state is entered when a node has received a minimally
valid LIE from a neighbor but not a ThreeWay valid LIE. valid LIE from a neighbor but not a ThreeWay valid LIE.
* ThreeWay: this state signifies that _ThreeWay_ valid LIEs from a * ThreeWay: This state signifies that _ThreeWay_ valid LIEs from a
neighbor have been received. On achieving this state the link can neighbor have been received. On achieving this state, the link
be advertised in _neighbors_ element in _NodeTIEElement_. can be advertised in the _neighbors_ element in _NodeTIEElement_.
* MultipleNeighborsWait: occurs normally when more than two nodes * MultipleNeighborsWait: Occurs normally when more than two nodes
become aware of each other on the same link or a remote node is become aware of each other on the same link or a remote node is
quickly reconfigured or rebooted without regressing to _OneWay_ quickly reconfigured or rebooted without regressing to _OneWay_
first. Each occurrence of the event SHOULD generate notification first. Each occurrence of the event SHOULD generate a
to help operational deployments. notification to help operational deployments.
Events: Events:
* TimerTick: one-second timer tick, i.e., the event is provided to * TimerTick: One-second timer tick, i.e., the event is provided to
the FSM once a second by an implementation-specific mechanism that the FSM once a second by an implementation-specific mechanism that
is outside the scope of this specification. This event is quietly is outside the scope of this specification. This event is quietly
ignored if the relevant transition does not exist. ignored if the relevant transition does not exist.
* LevelChanged: node's level has been changed by ZTP or * LevelChanged: Node's level has been changed by ZTP or
configuration. This is provided by the ZTP FSM. configuration. This is provided by the ZTP FSM.
* HALChanged: best HAL computed by ZTP has changed. This is * HALChanged: Best HAL computed by ZTP has changed. This is
provided by the ZTP FSM. provided by the ZTP FSM.
* HATChanged: HAT computed by ZTP has changed. This is provided by * HATChanged: HAT computed by ZTP has changed. This is provided by
the ZTP FSM. the ZTP FSM.
* HALSChanged: set of HAL offering systems computed by ZTP has * HALSChanged: Set of HAL offering systems computed by ZTP has
changed. This is provided by the ZTP FSM. changed. This is provided by the ZTP FSM.
* LieRcvd: received LIE on the interface. * LieRcvd: Received LIE on the interface.
* NewNeighbor: new neighbor is present in the received LIE. * NewNeighbor: New neighbor is present in the received LIE.
* ValidReflection: received valid reflection of this node from * ValidReflection: Received valid reflection of this node from the
neighbor, i.e. all elements in _neighbor_ element in _LiePacket_ neighbor, i.e., all elements in the _neighbor_ element in
have values corresponding to this link. _LiePacket_ have values corresponding to this link.
* NeighborDroppedReflection: lost previously held reflection from * NeighborDroppedReflection: Lost previously held reflection from
neighbor, i.e. _neighbor_ element in _LiePacket_ does not the neighbor, i.e., the _neighbor_ element in _LiePacket_ does not
correspond to this node or is not present. correspond to this node or is not present.
* NeighborChangedLevel: neighbor changed advertised level from the * NeighborChangedLevel: Neighbor changed the advertised level from
previously held one. the previously held one.
* NeighborChangedAddress: neighbor changed IP address, i.e. LIE has * NeighborChangedAddress: Neighbor changed the IP address, i.e., the
been received from an address different from previous LIEs. Those LIE has been received from an address different from previous
changes will influence the sockets used to listen to TIEs, TIREs, LIEs. Those changes will influence the sockets used to listen to
TIDEs. TIEs, TIREs, and TIDEs.
* UnacceptableHeader: Unacceptable header received. * UnacceptableHeader: Unacceptable header received.
* MTUMismatch: MTU mismatched. * MTUMismatch: MTU mismatched.
* NeighborChangedMinorFields: minor fields changed in neighbor's * NeighborChangedMinorFields: Minor fields changed in the neighbor's
LIE. LIE.
* HoldtimeExpired: adjacency holddown timer expired. * HoldtimeExpired: Adjacency holddown timer expired.
* MultipleNeighbors: more than one neighbor is present on interface * MultipleNeighbors: More than one neighbor is present on the
* MultipleNeighborsDone: multiple neighbors timer expired. interface.
* FloodLeadersChanged: node's election algorithm determined new set * MultipleNeighborsDone: Multiple neighbors' timers expired.
* FloodLeadersChanged: Node's election algorithm determined new set
of flood leaders. of flood leaders.
* SendLie: send a LIE out. * SendLie: Send a LIE out.
* UpdateZTPOffer: update this node's ZTP offer. This is sent to the * UpdateZTPOffer: Update this node's ZTP offer. This is sent to the
ZTP FSM. ZTP FSM.
Actions: Actions:
* on HATChanged in _OneWay_ finishes in OneWay: store HAT * on HATChanged in _OneWay_ finishes in OneWay: store HAT
* on FloodLeadersChanged in _OneWay_ finishes in OneWay: update * on FloodLeadersChanged in _OneWay_ finishes in OneWay: update
_you_are_flood_repeater_ LIE elements based on flood leader _you_are_flood_repeater_ LIE elements based on the flood leader
election results election results
* on UnacceptableHeader in _OneWay_ finishes in OneWay: no action * on UnacceptableHeader in _OneWay_ finishes in OneWay: no action
* on NeighborChangedMinorFields in _OneWay_ finishes in OneWay: no * on NeighborChangedMinorFields in _OneWay_ finishes in OneWay: no
action action
* on SendLie in _OneWay_ finishes in OneWay: SEND_LIE * on SendLie in _OneWay_ finishes in OneWay: SEND_LIE
* on HALSChanged in _OneWay_ finishes in OneWay: store HALS * on HALSChanged in _OneWay_ finishes in OneWay: store the HALS
* on MultipleNeighbors in _OneWay_ finishes in * on MultipleNeighbors in _OneWay_ finishes in
MultipleNeighborsWait: start multiple neighbors timer with MultipleNeighborsWait: start multiple neighbors' timers with the
interval _multiple_neighbors_lie_holdtime_multipler_ * interval _multiple_neighbors_lie_holdtime_multipler_ *
_default_lie_holdtime_ _default_lie_holdtime_
* on NeighborChangedLevel in _OneWay_ finishes in OneWay: no action * on NeighborChangedLevel in _OneWay_ finishes in OneWay: no action
* on LieRcvd in _OneWay_ finishes in OneWay: PROCESS_LIE * on LieRcvd in _OneWay_ finishes in OneWay: PROCESS_LIE
* on MTUMismatch in _OneWay_ finishes in OneWay: no action * on MTUMismatch in _OneWay_ finishes in OneWay: no action
* on ValidReflection in _OneWay_ finishes in ThreeWay: no action * on ValidReflection in _OneWay_ finishes in ThreeWay: no action
* on LevelChanged in _OneWay_ finishes in OneWay: update level with * on LevelChanged in _OneWay_ finishes in OneWay: update the level
event value, PUSH SendLie event with the event value, PUSH the SendLie event
* on HALChanged in _OneWay_ finishes in OneWay: store new HAL * on HALChanged in _OneWay_ finishes in OneWay: store the new HAL
* on HoldtimeExpired in _OneWay_ finishes in OneWay: no action * on HoldtimeExpired in _OneWay_ finishes in OneWay: no action
* on NeighborChangedAddress in _OneWay_ finishes in OneWay: no * on NeighborChangedAddress in _OneWay_ finishes in OneWay: no
action action
* on NewNeighbor in _OneWay_ finishes in TwoWay: PUSH SendLie event * on NewNeighbor in _OneWay_ finishes in TwoWay: PUSH the SendLie
event
* on UpdateZTPOffer in _OneWay_ finishes in OneWay: send offer to * on UpdateZTPOffer in _OneWay_ finishes in OneWay: send the offer
ZTP FSM to the ZTP FSM
* on NeighborDroppedReflection in _OneWay_ finishes in OneWay: no * on NeighborDroppedReflection in _OneWay_ finishes in OneWay: no
action action
* on TimerTick in _OneWay_ finishes in OneWay: PUSH SendLie event * on TimerTick in _OneWay_ finishes in OneWay: PUSH SendLie event
* on FloodLeadersChanged in _TwoWay_ finishes in TwoWay: update * on FloodLeadersChanged in _TwoWay_ finishes in TwoWay: update
_you_are_flood_repeater_ LIE elements based on flood leader _you_are_flood_repeater_ LIE elements based on the flood leader
election results election results
* on UpdateZTPOffer in _TwoWay_ finishes in TwoWay: send offer to * on UpdateZTPOffer in _TwoWay_ finishes in TwoWay: send the offer
ZTP FSM to the ZTP FSM
* on NewNeighbor in _TwoWay_ finishes in MultipleNeighborsWait: PUSH * on NewNeighbor in _TwoWay_ finishes in MultipleNeighborsWait: PUSH
SendLie event the SendLie event
* on ValidReflection in _TwoWay_ finishes in ThreeWay: no action * on ValidReflection in _TwoWay_ finishes in ThreeWay: no action
* on LieRcvd in _TwoWay_ finishes in TwoWay: PROCESS_LIE * on LieRcvd in _TwoWay_ finishes in TwoWay: PROCESS_LIE
* on UnacceptableHeader in _TwoWay_ finishes in OneWay: no action * on UnacceptableHeader in _TwoWay_ finishes in OneWay: no action
* on HALChanged in _TwoWay_ finishes in TwoWay: store new HAL * on HALChanged in _TwoWay_ finishes in TwoWay: store the new HAL
* on HoldtimeExpired in _TwoWay_ finishes in OneWay: no action * on HoldtimeExpired in _TwoWay_ finishes in OneWay: no action
* on LevelChanged in _TwoWay_ finishes in TwoWay: update level with * on LevelChanged in _TwoWay_ finishes in TwoWay: update the level
event value with the event value
* on TimerTick in _TwoWay_ finishes in TwoWay: PUSH SendLie event, * on TimerTick in _TwoWay_ finishes in TwoWay: PUSH SendLie event,
if last valid LIE was received more than _holdtime_ ago as if last valid LIE was received more than _holdtime_ ago as
advertised by neighbor then PUSH HoldtimeExpired event advertised by the neighbor, then PUSH the HoldtimeExpired event
* on HATChanged in _TwoWay_ finishes in TwoWay: store HAT * on HATChanged in _TwoWay_ finishes in TwoWay: store HAT
* on NeighborChangedLevel in _TwoWay_ finishes in OneWay: no action * on NeighborChangedLevel in _TwoWay_ finishes in OneWay: no action
* on HALSChanged in _TwoWay_ finishes in TwoWay: store HALS * on HALSChanged in _TwoWay_ finishes in TwoWay: store the HALS
* on MTUMismatch in _TwoWay_ finishes in OneWay: no action * on MTUMismatch in _TwoWay_ finishes in OneWay: no action
* on NeighborChangedAddress in _TwoWay_ finishes in OneWay: no * on NeighborChangedAddress in _TwoWay_ finishes in OneWay: no
action action
* on SendLie in _TwoWay_ finishes in TwoWay: SEND_LIE * on SendLie in _TwoWay_ finishes in TwoWay: SEND_LIE
* on MultipleNeighbors in _TwoWay_ finishes in * on MultipleNeighbors in _TwoWay_ finishes in
MultipleNeighborsWait: start multiple neighbors timer with MultipleNeighborsWait: start multiple neighbors' timers with the
interval _multiple_neighbors_lie_holdtime_multipler_ * interval _multiple_neighbors_lie_holdtime_multipler_ *
_default_lie_holdtime_ _default_lie_holdtime_
* on TimerTick in _ThreeWay_ finishes in ThreeWay: PUSH SendLie * on TimerTick in _ThreeWay_ finishes in ThreeWay: PUSH the SendLie
event, if last valid LIE was received more than _holdtime_ ago as event, if the last valid LIE was received more than _holdtime_ ago
advertised by neighbor then PUSH HoldtimeExpired event as advertised by the neighbor, then PUSH the HoldtimeExpired event
* on LevelChanged in _ThreeWay_ finishes in OneWay: update level * on LevelChanged in _ThreeWay_ finishes in OneWay: update the level
with event value with the event value
* on HATChanged in _ThreeWay_ finishes in ThreeWay: store HAT * on HATChanged in _ThreeWay_ finishes in ThreeWay: store HAT
* on MTUMismatch in _ThreeWay_ finishes in OneWay: no action * on MTUMismatch in _ThreeWay_ finishes in OneWay: no action
* on UnacceptableHeader in _ThreeWay_ finishes in OneWay: no action * on UnacceptableHeader in _ThreeWay_ finishes in OneWay: no action
* on MultipleNeighbors in _ThreeWay_ finishes in * on MultipleNeighbors in _ThreeWay_ finishes in
MultipleNeighborsWait: start multiple neighbors timer with MultipleNeighborsWait: start multiple neighbors' timers with the
interval _multiple_neighbors_lie_holdtime_multipler_ * interval _multiple_neighbors_lie_holdtime_multipler_ *
_default_lie_holdtime_ _default_lie_holdtime_
* on NeighborChangedLevel in _ThreeWay_ finishes in OneWay: no * on NeighborChangedLevel in _ThreeWay_ finishes in OneWay: no
action action
* on HALSChanged in _ThreeWay_ finishes in ThreeWay: store HALS * on HALSChanged in _ThreeWay_ finishes in ThreeWay: store the HALS
* on LieRcvd in _ThreeWay_ finishes in ThreeWay: PROCESS_LIE * on LieRcvd in _ThreeWay_ finishes in ThreeWay: PROCESS_LIE
* on FloodLeadersChanged in _ThreeWay_ finishes in ThreeWay: update * on FloodLeadersChanged in _ThreeWay_ finishes in ThreeWay: update
_you_are_flood_repeater_ LIE elements based on flood leader _you_are_flood_repeater_ LIE elements based on the flood leader
election results, PUSH SendLie election results, PUSH the SendLie event
* on NeighborDroppedReflection in _ThreeWay_ finishes in TwoWay: no * on NeighborDroppedReflection in _ThreeWay_ finishes in TwoWay: no
action action
* on HoldtimeExpired in _ThreeWay_ finishes in OneWay: no action * on HoldtimeExpired in _ThreeWay_ finishes in OneWay: no action
* on ValidReflection in _ThreeWay_ finishes in ThreeWay: no action * on ValidReflection in _ThreeWay_ finishes in ThreeWay: no action
* on UpdateZTPOffer in _ThreeWay_ finishes in ThreeWay: send offer * on UpdateZTPOffer in _ThreeWay_ finishes in ThreeWay: send the
to ZTP FSM offer to the ZTP FSM
* on NeighborChangedAddress in _ThreeWay_ finishes in OneWay: no * on NeighborChangedAddress in _ThreeWay_ finishes in OneWay: no
action action
* on HALChanged in _ThreeWay_ finishes in ThreeWay: store new HAL * on HALChanged in _ThreeWay_ finishes in ThreeWay: store the new
HAL
* on SendLie in _ThreeWay_ finishes in ThreeWay: SEND_LIE * on SendLie in _ThreeWay_ finishes in ThreeWay: SEND_LIE
* on MultipleNeighbors in MultipleNeighborsWait finishes in * on MultipleNeighbors in MultipleNeighborsWait finishes in
MultipleNeighborsWait: start multiple neighbors timer with MultipleNeighborsWait: start multiple neighbors' timers with the
interval _multiple_neighbors_lie_holdtime_multipler_ * interval _multiple_neighbors_lie_holdtime_multipler_ *
_default_lie_holdtime_ _default_lie_holdtime_
* on FloodLeadersChanged in MultipleNeighborsWait finishes in * on FloodLeadersChanged in MultipleNeighborsWait finishes in
MultipleNeighborsWait: update _you_are_flood_repeater_ LIE MultipleNeighborsWait: update _you_are_flood_repeater_ LIE
elements based on flood leader election results elements based on the flood leader election results
* on TimerTick in MultipleNeighborsWait finishes in * on TimerTick in MultipleNeighborsWait finishes in
MultipleNeighborsWait: check MultipleNeighbors timer, if timer MultipleNeighborsWait: check MultipleNeighbors timer, if the timer
expired PUSH MultipleNeighborsDone expired, PUSH MultipleNeighborsDone
* on ValidReflection in MultipleNeighborsWait finishes in * on ValidReflection in MultipleNeighborsWait finishes in
MultipleNeighborsWait: no action MultipleNeighborsWait: no action
* on UpdateZTPOffer in MultipleNeighborsWait finishes in * on UpdateZTPOffer in MultipleNeighborsWait finishes in
MultipleNeighborsWait: send offer to ZTP FSM MultipleNeighborsWait: send the offer to the ZTP FSM
* on NeighborDroppedReflection in MultipleNeighborsWait finishes in * on NeighborDroppedReflection in MultipleNeighborsWait finishes in
MultipleNeighborsWait: no action MultipleNeighborsWait: no action
* on LieRcvd in MultipleNeighborsWait finishes in * on LieRcvd in MultipleNeighborsWait finishes in
MultipleNeighborsWait: no action MultipleNeighborsWait: no action
* on UnacceptableHeader in MultipleNeighborsWait finishes in * on UnacceptableHeader in MultipleNeighborsWait finishes in
MultipleNeighborsWait: no action MultipleNeighborsWait: no action
* on NeighborChangedAddress in MultipleNeighborsWait finishes in * on NeighborChangedAddress in MultipleNeighborsWait finishes in
MultipleNeighborsWait: no action MultipleNeighborsWait: no action
* on LevelChanged in MultipleNeighborsWait finishes in OneWay: * on LevelChanged in MultipleNeighborsWait finishes in OneWay:
update level with event value update the level with the event value
* on HATChanged in MultipleNeighborsWait finishes in * on HATChanged in MultipleNeighborsWait finishes in
MultipleNeighborsWait: store HAT MultipleNeighborsWait: store HAT
* on MTUMismatch in MultipleNeighborsWait finishes in * on MTUMismatch in MultipleNeighborsWait finishes in
MultipleNeighborsWait: no action MultipleNeighborsWait: no action
* on HALSChanged in MultipleNeighborsWait finishes in * on HALSChanged in MultipleNeighborsWait finishes in
MultipleNeighborsWait: store HALS MultipleNeighborsWait: store the HALS
* on HALChanged in MultipleNeighborsWait finishes in * on HALChanged in MultipleNeighborsWait finishes in
MultipleNeighborsWait: store new HAL MultipleNeighborsWait: store the new HAL
* on HoldtimeExpired in MultipleNeighborsWait finishes in * on HoldtimeExpired in MultipleNeighborsWait finishes in
MultipleNeighborsWait: no action MultipleNeighborsWait: no action
* on SendLie in MultipleNeighborsWait finishes in * on SendLie in MultipleNeighborsWait finishes in
MultipleNeighborsWait: no action MultipleNeighborsWait: no action
* on MultipleNeighborsDone in MultipleNeighborsWait finishes in * on MultipleNeighborsDone in MultipleNeighborsWait finishes in
OneWay: no action OneWay: no action
* on Entry into OneWay: CLEANUP * on Entry into OneWay: CLEANUP
6.3. Topology Exchange (TIE Exchange) 6.3. Topology Exchange (TIE Exchange)
6.3.1. Topology Information Elements 6.3.1. Topology Information Elements
Topology and reachability information in RIFT is conveyed by TIEs. Topology and reachability information in RIFT is conveyed by TIEs.
The TIE exchange mechanism uses the port indicated by each node in The TIE exchange mechanism uses the port indicated by each node in
the LIE exchange as _flood_port_ in _LIEPacket_ and the interface on the LIE exchange as _flood_port_ in _LIEPacket_ and the interface on
which the adjacency has been formed as destination. TIEs MUST be which the adjacency has been formed as the destination. TIEs MUST be
sent with an IPv4 Time to Live (TTL) or an IPv6 Hop Limit (HL) of sent with an IPv4 Time to Live (TTL) or an IPv6 Hop Limit (HL) of
either 1 or 255 and also MUST be ignored if received with values either 1 or 255 and also MUST be ignored if received with values
different than 1 or 255. This helps to protect RIFT information from different than 1 or 255. This helps to protect RIFT information from
being accepted beyond a single L3 next-hop in the topology. TIEs being accepted beyond a single L3 next hop in the topology. TIEs
SHOULD be sent with network control precedence unless an SHOULD be sent with network control precedence unless an
implementation is prevented from doing so [RFC2474]. implementation is prevented from doing so [RFC2474].
TIEs contain sequence numbers, lifetimes, and a type. Each type has TIEs contain sequence numbers, lifetimes, and a type. Each type has
ample identifying number space and information is spread across ample identifying number space, and information is spread across
multiple TIEs with the same TIEElement type (this is true for all TIE multiple TIEs with the same TIEElement type (this is true for all TIE
types). types).
More information about the TIE structure can be found in the schema More information about the TIE structure can be found in the schema
in Section 7 starting with _TIEPacket_ root. in Section 7, starting with _TIEPacket_ root.
6.3.2. Southbound and Northbound TIE Representation 6.3.2. Southbound and Northbound TIE Representation
A central concept of RIFT is that each node represents itself A central concept of RIFT is that each node represents itself
differently depending on the direction in which it is advertising differently, depending on the direction in which it is advertising
information. More precisely, a spine node represents two different information. More precisely, a spine node represents two different
databases over its adjacencies depending on whether it advertises databases over its adjacencies, depending on whether it advertises
TIEs to the north or to the south/east-west. Those differing TIE TIEs to the north or to the south/east-west. Those differing TIE
databases are called either south- or northbound (South TIEs and databases are called either southbound or northbound (South TIEs and
North TIEs) depending on the direction of distribution. North TIEs), depending on the direction of distribution.
The North TIEs hold all of the node's adjacencies and local prefixes The North TIEs hold all of the node's adjacencies and local prefixes,
while the South TIEs hold only all of the node's adjacencies, the while the South TIEs hold all of the node's adjacencies, the default
default prefix with necessary disaggregated prefixes and local prefix with necessary disaggregated prefixes, and local prefixes.
prefixes. Section 6.5 explains further details. Section 6.5 explains further details.
All TIE types are mostly symmetrical in both directions. The All TIE types are mostly symmetrical in both directions. Section 7.3
(Section 7.3) defines the TIE types (i.e., the TIETypeType element) defines the TIE types (i.e., the TIETypeType element) and their
and their directionality (i.e., _direction_ within the _TIEID_ directionality (i.e., _direction_ within the _TIEID_ element).
element).
As an example illustrating a database holding both representations, As an example illustrating a database holding both representations,
the topology in Figure 2 with the optional link between spine 111 and the topology in Figure 2 with the optional link between spine 111 and
spine 112 (so that the flooding on an East-West link can be shown) is spine 112 (so that the flooding on an East-West link can be shown) is
shown below. Unnumbered interfaces are implicitly assumed and for shown below. Unnumbered interfaces are implicitly assumed and, for
simplicity, the key value elements which may be included in their simplicity, the key value elements, which may be included in their
South TIEs or North TIEs are not shown. First, in Figure 15 are the South TIEs or North TIEs, are not shown. First, Figure 15 shows the
TIEs generated by some nodes. TIEs generated by some nodes.
ToF 21 South TIEs: ToF 21 South TIEs:
Node South TIE: Node South TIE:
NodeTIEElement(level=2, NodeTIEElement(level=2,
neighbors( neighbors(
(Spine 111, level 1, cost 1, links(...)), (Spine 111, level 1, cost 1, links(...)),
(Spine 112, level 1, cost 1, links(...)), (Spine 112, level 1, cost 1, links(...)),
(Spine 121, level 1, cost 1, links(...)), (Spine 121, level 1, cost 1, links(...)),
(Spine 122, level 1, cost 1, links(...)) (Spine 122, level 1, cost 1, links(...))
) )
) )
Prefix South TIE: Prefix South TIE:
PrefixTIEElement(prefixes(0/0, metric 1), (::/0, metric 1)) PrefixTIEElement(prefixes(0/0, metric 1), (::/0, metric 1))
Spine 111 South TIEs:
Node South TIE:
NodeTIEElement(level=1,
neighbors(
(ToF 21, level 2, cost 1, links(...)),
(ToF 22, level 2, cost 1, links(...)),
(Spine 112, level 1, cost 1, links(...)),
(Leaf111, level 0, cost 1, links(...)),
(Leaf112, level 0, cost 1, links(...))
)
)
Prefix South TIE:
PrefixTIEElement(prefixes(0/0, metric 1), (::/0, metric 1))
Spine 111 North TIEs: Spine 111 South TIEs:
Node North TIE: Node South TIE:
NodeTIEElement(level=1, NodeTIEElement(level=1,
neighbors( neighbors(
(ToF 21, level 2, cost 1, links(...)), (ToF 21, level 2, cost 1, links(...)),
(ToF 22, level 2, cost 1, links(...)), (ToF 22, level 2, cost 1, links(...)),
(Spine 112, level 1, cost 1, links(...)), (Spine 112, level 1, cost 1, links(...)),
(Leaf111, level 0, cost 1, links(...)), (Leaf111, level 0, cost 1, links(...)),
(Leaf112, level 0, cost 1, links(...)) (Leaf112, level 0, cost 1, links(...))
) )
) )
Prefix North TIE: Prefix South TIE:
PrefixTIEElement(prefixes(Spine 111.loopback) PrefixTIEElement(prefixes(0/0, metric 1), (::/0, metric 1))
Spine 121 South TIEs: Spine 111 North TIEs:
Node South TIE: Node North TIE:
NodeTIEElement(level=1, NodeTIEElement(level=1,
neighbors( neighbors(
(ToF 21, level 2, cost 1, links(...)), (ToF 21, level 2, cost 1, links(...)),
(ToF 22, level 2, cost 1, links(...)), (ToF 22, level 2, cost 1, links(...)),
(Leaf121, level 0, cost 1, links(...)), (Spine 112, level 1, cost 1, links(...)),
(Leaf122, level 0, cost 1, links(...)) (Leaf111, level 0, cost 1, links(...)),
) (Leaf112, level 0, cost 1, links(...))
) )
Prefix South TIE: )
PrefixTIEElement(prefixes(0/0, metric 1), (::/0, metric 1)) Prefix North TIE:
PrefixTIEElement(prefixes(Spine 111.loopback)
Spine 121 North TIEs: Spine 121 South TIEs:
Node North TIE: Node South TIE:
NodeTIEElement(level=1, NodeTIEElement(level=1,
neighbors( neighbors(
(ToF 21, level 2, cost 1, links(...)), (ToF 21, level 2, cost 1, links(...)),
(ToF 22, level 2, cost 1, links(...)), (ToF 22, level 2, cost 1, links(...)),
(Leaf121, level 0, cost 1, links(...)), (Leaf121, level 0, cost 1, links(...)),
(Leaf122, level 0, cost 1, links(...)) (Leaf122, level 0, cost 1, links(...))
) )
) )
Prefix North TIE: Prefix South TIE:
PrefixTIEElement(prefixes(Spine 121.loopback) PrefixTIEElement(prefixes(0/0, metric 1), (::/0, metric 1))
Leaf112 North TIEs: Spine 121 North TIEs:
Node North TIE:
NodeTIEElement(level=1,
neighbors(
(ToF 21, level 2, cost 1, links(...)),
(ToF 22, level 2, cost 1, links(...)),
(Leaf121, level 0, cost 1, links(...)),
(Leaf122, level 0, cost 1, links(...))
)
)
Prefix North TIE:
PrefixTIEElement(prefixes(Spine 121.loopback)
Node North TIE: Leaf112 North TIEs:
NodeTIEElement(level=0, Node North TIE:
neighbors( NodeTIEElement(level=0,
(Spine 111, level 1, cost 1, links(...)), neighbors(
(Spine 112, level 1, cost 1, links(...)) (Spine 111, level 1, cost 1, links(...)),
) (Spine 112, level 1, cost 1, links(...))
) )
Prefix North TIE: )
PrefixTIEElement(prefixes(Leaf112.loopback, Prefix112, Prefix_MH)) Prefix North TIE:
PrefixTIEElement(prefixes(Leaf112.loopback, Prefix112, Prefix_MH))
Figure 15: Example TIEs Generated in a 2 Level Spine-and-Leaf Figure 15: Example TIEs Generated in a 2-Level Spine-and-Leaf
Topology Topology
It may not be obvious here as to why the Node South TIEs contain all It may not be obvious here as to why the Node South TIEs contain all
the adjacencies of the corresponding node. This will be necessary the adjacencies of the corresponding node. This will be necessary
for algorithms further elaborated on in Section 6.3.9 and for algorithms further elaborated on in Sections 6.3.9 and 6.8.7.
Section 6.8.7.
For Node TIEs to carry more adjacencies than fit into an MTU-sized For Node TIEs to carry more adjacencies than fit into an MTU-sized
packet, the element _neighbors_ may contain a different set of packet, the _neighbors_ element may contain a different set of
neighbors in each TIE. Those disjointed sets of neighbors MUST be neighbors in each TIE. Those disjointed sets of neighbors MUST be
joined during corresponding computation. However, if the following joined during corresponding computation. However, if the following
occurs across multiple Node TIEs occurs across multiple Node TIEs:
1. _capabilities_ do not match *or* 1. _capabilities_ do not match,
2. _flags_ values do not match *or* 2. _flags_ values do not match, *or*
3. same neighbor repeats in multiple TIEs with different values 3. the same neighbor repeats in multiple TIEs with different values.
The implementation is expected to use the value of any of the valid The implementation is expected to use the value of any of the valid
TIEs it received as it cannot control the arrival order of those TIEs it received, as it cannot control the arrival order of those
TIEs. TIEs.
The _miscabled_links_ element SHOULD be included in every Node TIE, The _miscabled_links_ element SHOULD be included in every Node TIE;
otherwise the behavior is undefined. otherwise, the behavior is undefined.
A ToF node MUST include information on all other ToFs it is aware of A ToF node MUST include information on all other ToFs it is aware of
through reflection. The _same_plane_tofs_ element is used to carry through reflection. The _same_plane_tofs_ element is used to carry
this information. To prevent MTU overrun problems, multiple Node this information. To prevent MTU overrun problems, multiple Node
TIEs can carry disjointed sets of ToFs which MUST be joined to form a TIEs can carry disjointed sets of ToFs, which MUST be joined to form
single set. a single set.
Different TIE types are carried in _TIEElement_. Schema enum Different TIE types are carried in _TIEElement_. Schema enum
`common.TIETypeType` in _TIEID_ indicates which elements MUST be 'common.TIETypeType' in _TIEID_ indicates which elements MUST be
present in the _TIEElement_. In case of a mismatch between the present in _TIEElement_. In case of a mismatch between _TIETypeType_
_TIETypeType_ in the _TIEID_ and the present element, the unexpected in the _TIEID_ and the present element, the unexpected elements MUST
elements MUST be ignored. In case of lack of expected element in the be ignored. In case of the lack of an expected element in the TIE,
TIE an error MUST be reported and the TIE MUST be ignored. The an error MUST be reported and the TIE MUST be ignored. The
element _positive_disaggregation_prefixes_ and _positive_disaggregation_prefixes_ and
_positive_external_disaggregation_prefixes_ MUST be advertised _positive_external_disaggregation_prefixes_ elements MUST be
southbound only and ignored in North TIEs. The element advertised southbound only and ignored in North TIEs. The
_negative_disaggregation_prefixes_ MUST be propagated according to _negative_disaggregation_prefixes_ element MUST be propagated,
Section 6.5.2 southwards towards lower levels to heal pathological according to Section 6.5.2, southwards towards lower levels to heal
upper-level partitioning, otherwise traffic loss may occur in pathological upper-level partitioning; otherwise, traffic loss may
multiplane fabrics. It MUST NOT be advertised within a North TIE and occur in multi-plane fabrics. It MUST NOT be advertised within a
MUST be ignored otherwise. North TIE and MUST be ignored otherwise.
6.3.3. Flooding 6.3.3. Flooding
As described before, TIEs themselves are transported over UDP with As described before, TIEs themselves are transported over UDP with
the ports indicated in the LIE exchanges and using the destination the ports indicated in the LIE exchanges and use the destination
address on which the LIE adjacency has been formed. address on which the LIE adjacency has been formed.
TIEs are uniquely identified by the _TIEID_ schema element. The TIEs are uniquely identified by the _TIEID_ schema element. _TIEID_
_TIEID_ induces a total order achieved by comparing the elements in induces a total order achieved by comparing the elements in sequence
sequence defined in the element and comparing each value as an defined in the element and comparing each value as an unsigned
unsigned integer of corresponding length. The _TIEHeader_ element integer of corresponding length. The _TIEHeader_ element contains a
contains a _seq_nr_ element to distinguish newer versions of same _seq_nr_ element to distinguish newer versions of the same TIE.
TIE.
The _TIEHeader_ can also carry an _origination_time_ schema element _TIEHeader_ can also carry an _origination_time_ schema element (for
(for fabrics that utilize precision timing) which contains the fabrics that utilize precision timing) that contains the absolute
absolute timestamp of when the TIE was generated and an timestamp of when the TIE was generated and an _origination_lifetime_
_origination_lifetime_ to indicate the original lifetime when the TIE to indicate the original lifetime when the TIE was generated. When
was generated. When carried, they can be used for debugging or carried, they can be used for debugging or security purposes (e.g.,
security purposes (e.g. to prevent lifetime modification attacks). to prevent lifetime modification attacks). Clock synchronization is
Clock synchronization is considered in more detail in Section 6.8.4. considered in more detail in Section 6.8.4.
_remaining_lifetime_ counts down to 0 from _origination_lifetime_. _remaining_lifetime_ counts down to 0 from _origination_lifetime_.
TIEs with lifetimes differing by less than _lifetime_diff2ignore_ TIEs with lifetimes differing by less than _lifetime_diff2ignore_
MUST be considered EQUAL (if all other fields are equal). This MUST be considered EQUAL (if all other fields are equal). This
constant MUST be larger than _purge_lifetime_ to avoid constant MUST be larger than _purge_lifetime_ to avoid
retransmissions. retransmissions.
This normative ordering methodology is described in Figure 16 and This normative ordering methodology is described in Figure 16 and
MUST be used by all implementations. MUST be used by all implementations.
function Compare(X: TIEHeader, Y: TIEHeader) returns Ordering: function Compare(X: TIEHeader, Y: TIEHeader) returns Ordering:
seq_nr of a TIEHeader = TIEHeader.seq_nr seq_nr of a TIEHeader = TIEHeader.seq_nr
TIEID of a TIEHeader = TIEHeader.TIEID TIEID of a TIEHeader = TIEHeader.TIEID
direction of a TIEID = TIEID.direction direction of a TIEID = TIEID.direction
# System ID # System ID
originator of a TIEID = TIEID.originator originator of a TIEID = TIEID.originator
# is of type TIETypeType # is of type TIETypeType
skipping to change at page 57, line 31 skipping to change at line 2553
else if X.direction < Y.direction: else if X.direction < Y.direction:
return Y is larger return Y is larger
else if X.originator > Y.originator: else if X.originator > Y.originator:
return X is larger return X is larger
else if X.originator < Y.originator: else if X.originator < Y.originator:
return Y is larger return Y is larger
else: else:
if X.tietype == Y.tietype: if X.tietype == Y.tietype:
if X.tie_nr == Y.tie_nr: if X.tie_nr == Y.tie_nr:
if X.seq_nr == Y.seq_nr: if X.seq_nr == Y.seq_nr:
X.lifetime_left = X.remaining_lifetime - time since TIE was received X.lifetime_left = X.remaining_lifetime
Y.lifetime_left = Y.remaining_lifetime - time since TIE was received - time since TIE was received
Y.lifetime_left = Y.remaining_lifetime
- time since TIE was received
if absolute_value_of(X.lifetime_left - Y.lifetime_left) <= common.lifetime_diff2ignore: if absolute_value_of(X.lifetime_left -
Y.lifetime_left) <= common.lifetime_diff2ignore:
return Both are Equal return Both are Equal
else: else:
return TIEHeader with larger lifetime_left is larger return TIEHeader with larger lifetime_left is
larger
else: else:
return return TIEHeader with larger seq_nr is larger return TIEHeader with larger seq_nr is larger
else: else:
return TIEHeader with larger tie_nr is larger return TIEHeader with larger tie_nr is larger
else: else:
return TIEHeader with larger TIEType is larger return TIEHeader with larger TIEType is larger
Figure 16: TIEHeader Comparison Function Figure 16: TIEHeader Comparison Function
All valid TIE types are defined in _TIETypeType_. This enum All valid TIE types are defined in _TIETypeType_. This enum
indicates what TIE type the TIE is carrying. In case the value is indicates what TIE type the TIE is carrying. In case the value is
not known to the receiver, the TIE MUST be re-flooded with scope not known to the receiver, the TIE MUST be reflooded with the scope
identical to the scope of a prefix TIE. This allows for future identical to the scope of a prefix TIE. This allows for future
extensions of the protocol within the same major schema with types extensions of the protocol within the same major schema with types
opaque to some nodes with some restrictions defined in Section 7. opaque to some nodes with some restrictions defined in Section 7.
6.3.3.1. Normative Flooding Procedures 6.3.3.1. Normative Flooding Procedures
On reception of a TIE with an undefined level value in the packet On reception of a TIE with an undefined level value in the packet
header the node MUST issue a warning and discard the packet. header, the node MUST issue a warning and discard the packet.
This section specifies the precise, normative flooding mechanism and This section specifies the precise, normative flooding mechanism and
can be omitted unless the reader is pursuing an implementation of the can be omitted unless the reader is pursuing an implementation of the
protocol or looks for a deep understanding of underlying information protocol or looks for a deep understanding of underlying information
distribution mechanism. distribution mechanism.
Flooding Procedures are described in terms of the flooding state of Flooding procedures are described in terms of the flooding state of
an adjacency and resulting operations on it driven by packet an adjacency, and resulting operations on it are driven by packet
arrivals. Implementations MUST implement a behavior that is arrivals. Implementations MUST implement a behavior that is
externally indistinguishable from the FSMs and normative procedures externally indistinguishable from the FSMs and normative procedures
given here. given here.
RIFT does not specify any kind of flood rate limiting. To help with RIFT does not specify any kind of flood rate limiting. To help with
adjustment of flooding speeds the encoded packets provide hints to adjustment of flooding speeds, the encoded packets provide hints to
react accordingly to losses or overruns via react accordingly to losses or overruns via
_you_are_sending_too_quickly_ in the _LIEPacket_ and `Packet Number` _you_are_sending_too_quickly_ in the _LIEPacket_ and "Packet Number"
in the security envelope described in Section 6.9.3. Flooding of all in the security envelope described in Section 6.9.3. Flooding of all
corresponding topology exchange elements SHOULD be performed at the corresponding topology exchange elements SHOULD be performed at the
highest feasible rate but the rate of transmission MUST be throttled highest feasible rate, but the rate of transmission MUST be throttled
by reacting to packet elements and features of the system such as by reacting to packet elements and features of the system, such as
e.g. queue lengths or congestion indications in the protocol packets. queue lengths or congestion indications in the protocol packets.
A node SHOULD NOT send out any topology information elements if the A node SHOULD NOT send out any topology information elements if the
adjacency is not in a "ThreeWay" state. No further tightening of adjacency is not in a _ThreeWay_ state. No further tightening of
this rule is possible. For example, link buffering may cause both this rule is possible. For example, link buffering may cause both
LIEs and TIEs/TIDEs/TIREs to be re-ordered. LIEs and TIEs/TIDEs/TIREs to be reordered.
A node MUST drop any received TIEs/TIDEs/TIREs unless it is in A node MUST drop any received TIEs/TIDEs/TIREs unless it is in the
_ThreeWay_ state. _ThreeWay_ state.
TIEs generated by other nodes MUST be re-flooded. TIDEs and TIREs TIEs generated by other nodes MUST be reflooded. TIDEs and TIREs
MUST NOT be re-flooded. MUST NOT be reflooded.
6.3.3.1.1. FloodState Structure per Adjacency 6.3.3.1.1. FloodState Structure per Adjacency
The structure contains conceptually for each adjacency the following For each adjacency, the structure conceptually contains the following
elements. The word "collection" or "queue" indicates a set of elements. The word "collection" or "queue" indicates a set of
elements that can be iterated over: elements that can be iterated over the following:
TIES_TX: TIES_TX:
Collection containing all the TIEs to transmit on the adjacency. Collection containing all the TIEs to transmit on the adjacency.
TIES_ACK: TIES_ACK:
Collection containing all the TIEs that have to be acknowledged on Collection containing all the TIEs that have to be acknowledged on
the adjacency. the adjacency.
TIES_REQ: TIES_REQ:
Collection containing all the TIE headers that have to be Collection containing all the TIE headers that have to be
skipping to change at page 59, line 31 skipping to change at line 2644
TIES_RTX: TIES_RTX:
Collection containing all TIEs that need retransmission with the Collection containing all TIEs that need retransmission with the
corresponding time to retransmit. corresponding time to retransmit.
FILTERED_TIEDB: FILTERED_TIEDB:
A filtered view of TIEDB, which retains for consideration only A filtered view of TIEDB, which retains for consideration only
those headers permitted by is_tide_entry_filtered and which either those headers permitted by is_tide_entry_filtered and which either
have a lifetime left > 0 or have no content. have a lifetime left > 0 or have no content.
Following words are used for well-known elements and procedures The following words are used for well-known elements and procedures
operating on this structure: operating on this structure:
TIE: TIE:
Describes either a full RIFT TIE or just the _TIEHeader_ or describes either a full RIFT TIE or just the _TIEHeader_ or
_TIEID_ equivalent as defined in Section 7.3. The corresponding _TIEID_ equivalent, as defined in Section 7.3. The corresponding
meaning is unambiguously contained in the context of each meaning is unambiguously contained in the context of each
algorithm. algorithm.
is_flood_reduced(TIE): is_flood_reduced(TIE):
returns whether a TIE can be flood reduced or not. returns whether a TIE can be flood-reduced or not.
is_tide_entry_filtered(TIE): is_tide_entry_filtered(TIE):
returns whether a header should be propagated in TIDE according to returns whether a header should be propagated in TIDE according to
flooding scopes. flooding scopes.
is_request_filtered(TIE): is_request_filtered(TIE):
returns whether a TIE request should be propagated to neighbor or returns whether a TIE request should be propagated to the neighbor
not according to flooding scopes. or not, according to flooding scopes.
is_flood_filtered(TIE): is_flood_filtered(TIE):
returns whether a TIE requested be flooded to neighbor or not returns whether a TIE requested be flooded to the neighbor or not,
according to flooding scopes. according to flooding scopes.
try_to_transmit_tie(TIE): try_to_transmit_tie(TIE):
A. if not is_flood_filtered(TIE) then if not is_flood_filtered(TIE), then
1. remove TIE from TIES_RTX if present 1. remove the TIE from TIES_RTX if present
2. if TIE with same key is found on TIES_ACK then 2. if the TIE with same key is found on TIES_ACK, then
a. if TIE is same or newer than TIE do nothing else a. if the TIE is the same as or newer than TIE, do nothing,
else
b. remove TIE from TIES_ACK and add TIE to TIES_TX b. remove the TIE from TIES_ACK and add TIE to TIES_TX
3. else insert TIE into TIES_TX 3. else insert the TIE into TIES_TX.
ack_tie(TIE): ack_tie(TIE):
remove TIE from all collections and then insert TIE into TIES_ACK. remove the TIE from all collections and then insert the TIE into
TIES_ACK.
tie_been_acked(TIE): tie_been_acked(TIE):
remove TIE from all collections. remove the TIE from all collections.
remove_from_all_queues(TIE): remove_from_all_queues(TIE):
same as _tie_been_acked_. same as _tie_been_acked_.
request_tie(TIE): request_tie(TIE):
if not is_request_filtered(TIE) then remove_from_all_queues(TIE) if not is_request_filtered(TIE), then remove_from_all_queues(TIE)
and add to TIES_REQ. and add to TIES_REQ.
move_to_rtx_list(TIE): move_to_rtx_list(TIE):
remove TIE from TIES_TX and then add to TIES_RTX using TIE remove the TIE from TIES_TX and then add to TIES_RTX, using the
retransmission interval. TIE retransmission interval.
clear_requests(TIEs): clear_requests(TIEs):
remove all TIEs from TIES_REQ. remove all TIEs from TIES_REQ.
bump_own_tie(TIE): bump_own_tie(TIE):
for self-originated TIE originate an empty or re-generate with for a self-originated TIE, originate an empty or regenerate with
version number higher than the one in TIE. the version number higher than the one in the TIE.
The collection SHOULD be served with the following priorities if the The collection SHOULD be served with the following priorities if the
system cannot process all the collections in real time: system cannot process all the collections in real time:
1. Elements on TIES_ACK should be processed with highest priority 1. Elements on TIES_ACK should be processed with highest priority
2. TIES_TX 2. TIES_TX
3. TIES_REQ and TIES_RTX should be processed with lowest priority 3. TIES_REQ and TIES_RTX should be processed with lowest priority
6.3.3.1.2. TIDEs 6.3.3.1.2. TIDEs
_TIEID_ and _TIEHeader_ space forms a strict total order (modulo _TIEID_ and _TIEHeader_ spaces form a strict total order (modulo
incomparable sequence numbers (found in `TIEHeader.seq_nr`) as incomparable sequence numbers (found in "TIEHeader.seq_nr"), as
explained in Appendix A in the very unlikely event that can occur if explained in Appendix A, in the very unlikely event that a TIE is
a TIE is "stuck" in a part of a network while the originator reboots "stuck" in a part of a network while the originator reboots and
and reissues TIEs many times to the point its sequence# rolls over reissues TIEs many times to the point its sequence number rolls over
and forms incomparable distance to the "stuck" copy) which implies and forms an incomparable distance to the "stuck" copy), which
that a comparison relation is possible between two elements. With implies that a comparison relation is possible between two elements.
that it is implicitly possible to compare TIEs, TIEHeaders and TIEIDs With that, it is implicitly possible to compare TIEs, TIEHeaders, and
to each other whereas the shortest viable key is always implied. TIEIDs to each other, whereas the shortest viable key is always
implied.
6.3.3.1.2.1. TIDE Generation 6.3.3.1.2.1. TIDE Generation
As given by timer constant, periodically generate TIDEs by: As given by the timer constant, periodically generate TIDEs by:
NEXT_TIDE_ID: ID of next TIE to be sent in TIDE. NEXT_TIDE_ID: ID of the next TIE to be sent in the TIDE.
a. NEXT_TIDE_ID = MIN_TIEID 1. NEXT_TIDE_ID = MIN_TIEID
b. while NEXT_TIDE_ID not equal to MAX_TIEID do 2. while NEXT_TIDE_ID is not equal to MAX_TIEID, do the following:
1. HEADERS = Exactly TIRDEs_PER_PKT headers from FILTERED_TIEDB a. HEADERS = Exactly TIRDEs_PER_PKT headers from FILTERED_TIEDB
starting at NEXT_TIDE_ID, unless fewer than TIRDEs_PER_PKT starting at NEXT_TIDE_ID, unless fewer than TIRDEs_PER_PKT
remain, in which case all remaining headers. remain, in which case all remaining headers.
2. if HEADERS is empty then START = MIN_TIEID else START = first b. if HEADERS is empty, then START = MIN_TIEID, else START =
element in HEADERS first element in HEADERS
3. if HEADERS' size less than TIRDEs_PER_PKT then END = c. if HEADERS' size is less than TIRDEs_PER_PKT, then END =
MAX_TIEID else END = last element in HEADERS MAX_TIEID, else END = last element in HEADERS
4. send *sorted* HEADERS as TIDE setting START and END as its d. send *sorted* HEADERS the as TIDE, setting START and END as
range its range
5. NEXT_TIDE_ID = END e. NEXT_TIDE_ID = END
The constant _TIRDEs_PER_PKT_ SHOULD be computed per interface and The constant _TIRDEs_PER_PKT_ SHOULD be computed per interface and
used by the implementation to limit the amount of TIE headers per used by the implementation to limit the amount of TIE headers per
TIDE so the sent TIDE PDU does not exceed interface MTU. TIDE so the sent TIDE PDU does not exceed the interface of MTU.
TIDE PDUs SHOULD be spaced on sending to prevent packet drops. TIDE PDUs SHOULD be spaced on sending to prevent packet drops.
The algorithm will intentionally enter the loop once and send a The algorithm will intentionally enter the loop once and send a
single TIDE even when the database is empty, otherwise no TIDEs would single TIDE, even when the database is empty; otherwise, no TIDEs
be sent for in case of empty database and break intended would be sent for in case of an empty database and break the intended
synchronization. synchronization.
6.3.3.1.2.2. TIDE Processing 6.3.3.1.2.2. TIDE Processing
On reception of TIDEs the following processing is performed: On reception of TIDEs, the following processing is performed:
TXKEYS: Collection of TIE Headers to be sent after processing of TXKEYS: Collection of TIE headers to be sent after processing of the
the packet packet
REQKEYS: Collection of TIEIDs to be requested after processing of REQKEYS: Collection of TIEIDs to be requested after processing of
the packet the packet
CLEARKEYS: Collection of TIEIDs to be removed from flood state CLEARKEYS: Collection of TIEIDs to be removed from flood state
queues queues
LASTPROCESSED: Last processed TIEID in TIDE LASTPROCESSED: Last processed TIEID in the TIDE
DBTIE: TIE in the Link State Database (LSDB) if found DBTIE: TIE in the Link State Database (LSDB), if found
a. LASTPROCESSED = TIDE.start_range 1. LASTPROCESSED = TIDE.start_range
b. for every HEADER in TIDE do 2. For every HEADER in the TIDE, do the following:
1. DBTIE = find HEADER in current LSDB a. DBTIE = find HEADER in the current LSDB
2. if HEADER < LASTPROCESSED then report error and reset b. if HEADER < LASTPROCESSED, then report the error and reset
adjacency and return the adjacency and return
3. put all TIEs in LSDB where (TIE.HEADER > LASTPROCESSED and c. put all TIEs in LSDB, where TIE.HEADER > LASTPROCESSED and
TIE.HEADER < HEADER) into TXKEYS TIE.HEADER < HEADER, into TXKEYS
4. LASTPROCESSED = HEADER d. LASTPROCESSED = HEADER
5. if DBTIE not found then e. if DBTIE is not found, then
I) if originator is this node, then bump_own_tie i. if originator is this node, then bump_own_tie
II) else put HEADER into REQKEYS ii. else put HEADER into REQKEYS
6. if DBTIE.HEADER < HEADER then f. if DBTIE.HEADER < HEADER, then
I) if originator is this node then bump_own_tie else i. if the originator is this node, then bump_own_tie, else
i. if this is a North TIE header from a northbound 1. if this is a North TIE header from a northbound
neighbor then override DBTIE in LSDB with HEADER neighbor, then override DBTIE in LSDB with HEADER
ii. else put HEADER into REQKEYS 2. else put HEADER into REQKEYS
7. if DBTIE.HEADER > HEADER then put DBTIE.HEADER into TXKEYS g. if DBTIE.HEADER > HEADER, then put DBTIE.HEADER into TXKEYS
8. if DBTIE.HEADER = HEADER then h. if DBTIE.HEADER = HEADER, then
I) if DBTIE has content already then put DBTIE.HEADER into i. if DBTIE has content already, then put DBTIE.HEADER into
CLEARKEYS CLEARKEYS, else
II) else put HEADER into REQKEYS ii. put HEADER into REQKEYS
c. put all TIEs in LSDB where (TIE.HEADER > LASTPROCESSED and 3. put all TIEs in LSDB, where TIE.HEADER > LASTPROCESSED and
TIE.HEADER <= TIDE.end_range) into TXKEYS TIE.HEADER <= TIDE.end_range, into TXKEYS
d. for all TIEs in TXKEYS try_to_transmit_tie(TIE) 4. for all TIEs in TXKEYS, try_to_transmit_tie(TIE)
e. for all TIEs in REQKEYS request_tie(TIE) 5. for all TIEs in REQKEYS, request_tie(TIE)
f. for all TIEs in CLEARKEYS remove_from_all_queues(TIE) 6. for all TIEs in CLEARKEYS, remove_from_all_queues(TIE)
6.3.3.1.3. TIREs 6.3.3.1.3. TIREs
6.3.3.1.3.1. TIRE Generation 6.3.3.1.3.1. TIRE Generation
Elements from both TIES_REQ and TIES_ACK MUST be collected and sent Elements from both TIES_REQ and TIES_ACK MUST be collected and sent
out as fast as feasible as TIREs. When sending TIREs with elements out as fast as feasible as TIREs. When sending TIREs with elements
from TIES_REQ the _remaining_lifetime_ field in from TIES_REQ, the _remaining_lifetime_ field in
_TIEHeaderWithLifeTime_ MUST be set to 0 to force reflooding from the _TIEHeaderWithLifeTime_ MUST be set to 0 to force reflooding from the
neighbor even if the TIEs seem to be same. neighbor even if the TIEs seem to be the same.
6.3.3.1.3.2. TIRE Processing 6.3.3.1.3.2. TIRE Processing
On reception of TIREs the following processing is performed: On reception of TIREs, the following processing is performed:
TXKEYS: Collection of TIE Headers to be sent after processing of TXKEYS: Collection of TIE headers to be sent after processing of the
the packet packet
REQKEYS: Collection of TIEIDs to be requested after processing of REQKEYS: Collection of TIEIDs to be requested after processing of
the packet the packet
ACKKEYS: Collection of TIEIDs that have been acked ACKKEYS: Collection of TIEIDs that have been acknowledged
DBTIE: TIE in the LSDB if found DBTIE: TIE in the LSDB, if found
a. for every HEADER in TIRE do 1. for every HEADER in TIRE, do the following:
1. DBTIE = find HEADER in current LSDB a. DBTIE = find HEADER in the current LSDB
2. if DBTIE not found then do nothing
3. if DBTIE.HEADER < HEADER then put HEADER into REQKEYS b. if DBTIE is not found, then do nothing
4. if DBTIE.HEADER > HEADER then put DBTIE.HEADER into TXKEYS c. if DBTIE.HEADER < HEADER, then put HEADER into REQKEYS
5. if DBTIE.HEADER = HEADER then put DBTIE.HEADER into ACKKEYS d. if DBTIE.HEADER > HEADER, then put DBTIE.HEADER into TXKEYS
b. for all TIEs in TXKEYS try_to_transmit_tie(TIE) e. if DBTIE.HEADER = HEADER, then put DBTIE.HEADER into ACKKEYS
c. for all TIEs in REQKEYS request_tie(TIE) 2. for all TIEs in TXKEYS, try_to_transmit_tie(TIE)
d. for all TIEs in ACKKEYS tie_been_acked(TIE) 3. for all TIEs in REQKEYS, request_tie(TIE)
4. for all TIEs in ACKKEYS, tie_been_acked(TIE)
6.3.3.1.4. TIEs Processing on Flood State Adjacency 6.3.3.1.4. TIEs Processing on Flood State Adjacency
On reception of TIEs the following processing is performed: On reception of TIEs, the following processing is performed:
ACKTIE: TIE to acknowledge ACKTIE: TIE to acknowledge
TXTIE: TIE to transmit TXTIE: TIE to transmit
DBTIE: TIE in the LSDB if found DBTIE: TIE in the LSDB, if found
a. DBTIE = find TIE in current LSDB 1. DBTIE = find TIE in the current LSDB
b. if DBTIE not found then 2. if DBTIE is not found, then
1. if originator is this node then bump_own_tie with a short a. if the originator is this node, then bump_own_tie with a
remaining lifetime short remaining lifetime, else
2. else insert TIE into LSDB and ACKTIE = TIE b. insert TIE into LSDB and ACKTIE = TIE
else else
1. if DBTIE.HEADER = TIE.HEADER then a. if DBTIE.HEADER = TIE.HEADER, then
i. if DBTIE has content already then ACKTIE = TIE i. if DBTIE has content already, then ACKTIE = TIE, else
ii. else process like the "DBTIE.HEADER < TIE.HEADER" case ii. process like the "DBTIE.HEADER < TIE.HEADER" case
2. if DBTIE.HEADER < TIE.HEADER then b. if DBTIE.HEADER < TIE.HEADER, then
i. if originator is this node then bump_own_tie i. if the originator is this node, then bump_own_tie, else
ii. else insert TIE into LSDB and ACKTIE = TIE ii. insert TIE into LSDB and ACKTIE = TIE
3. if DBTIE.HEADER > TIE.HEADER then c. if DBTIE.HEADER > TIE.HEADER, then
i. if DBTIE has content already then TXTIE = DBTIE
ii. else ACKTIE = DBTIE i. if DBTIE has content already, then TXTIE = DBTIE, else
c. if TXTIE is set then try_to_transmit_tie(TXTIE) ii. ACKTIE = DBTIE
d. if ACKTIE is set then ack_tie(TIE) 3. if TXTIE is set, then try_to_transmit_tie(TXTIE)
4. if ACKTIE is set, then ack_tie(TIE)
6.3.3.1.5. Sending TIEs 6.3.3.1.5. Sending TIEs
On a periodic basis all TIEs with lifetime left > 0 MUST be sent out On a periodic basis, all TIEs with a lifetime of > 0 left MUST be
on the adjacency, removed from TIES_TX list and requeued onto sent out on the adjacency, removed from the TIES_TX list, and
TIES_RTX list. The specific period is out of scope for this requeued onto TIES_RTX list. The specific period is out of scope for
document. this document.
6.3.3.1.6. TIEs Processing In LSDB 6.3.3.1.6. TIEs Processing in LSDB
The Link State Database (LSDB) holds the most recent copy of TIEs The Link State Database (LSDB) holds the most recent copy of TIEs
received via flooding from according peers. Consecutively, after received via flooding from according peers. Consecutively, after
version tie-breaking by LSDB, a peer receives from the LSDB the version tie-breaking by LSDB, a peer receives from the LSDB the
newest versions of TIEs received by other peers and processes them newest versions of TIEs received by other peers and processes them
(without any filtering) just like receiving TIEs from its remote (without any filtering) just like receiving TIEs from its remote
peer. Such a publisher model can be implemented in several ways, peer. Such a publisher model can be implemented in several ways,
either in a single thread of execution or in multiple parallel either in a single thread of execution or in multiple parallel
threads. threads.
LSDB can be logically considered as the entity aging out TIEs, i.e. LSDB can be logically considered as the entity aging out TIEs, i.e.,
being responsible to discard TIEs that are stored longer than being responsible to discard TIEs that are stored longer than
_remaining_lifetime_ on their reception. _remaining_lifetime_ on their reception.
LSDB is also expected to periodically re-originate the node's own LSDB is also expected to periodically reoriginate the node's own
TIEs. Originating at an interval significantly shorter than TIEs. Originating at an interval significantly shorter than
_default_lifetime_ is RECOMMENDED to prevent TIE expiration by other _default_lifetime_ is RECOMMENDED to prevent TIE expiration by other
nodes in the network which can lead to instabilities. nodes in the network, which can lead to instabilities.
6.3.4. TIE Flooding Scopes 6.3.4. TIE Flooding Scopes
In a somewhat analogous fashion to link-local, area and domain In a somewhat analogous fashion to link-local, area, and domain
flooding scopes, RIFT defines several complex "flooding scopes" flooding scopes, RIFT defines several complex "flooding scopes",
depending on the direction and type of TIE propagated. depending on the direction and type of TIE propagated.
Every North TIE is flooded northbound, providing a node at a given Every North TIE is flooded northbound, providing a node at a given
level with the complete topology of the Clos or Fat Tree network that level with the complete topology of the Clos or Fat Tree network that
is reachable southwards of it, including all specific prefixes. This is reachable southwards of it, including all specific prefixes. This
means that a packet received from a node at the same or lower level means that a packet received from a node at the same or lower level
whose destination is covered by one of those specific prefixes will whose destination is covered by one of those specific prefixes will
be routed directly towards the node advertising that prefix rather be routed directly towards the node advertising that prefix, rather
than sending the packet to a node at a higher level. than sending the packet to a node at a higher level.
A node's Node South TIEs, consisting of all node's adjacencies and A node's Node South TIEs, consisting of all node's adjacencies and
prefix South TIEs limited to those related to default IP prefix and prefix South TIEs limited to those related to default IP prefix and
disaggregated prefixes, are flooded southbound in order to inform disaggregated prefixes, are flooded southbound in order to inform
nodes one level down of connectivity of the higher level as well as nodes one level down of connectivity of the higher level as well as
reachability to the rest of the fabric. In order to allow an E-W reachability to the rest of the fabric. In order to allow an E-W
disconnected node in a given level to receive the South TIEs of other disconnected node in a given level to receive the South TIEs of other
nodes at its level, every *NODE* South TIE is "reflected" northbound nodes at its level, every Node South TIE is "reflected" northbound to
to the level from which it was received. It should be noted that the level from which it was received. It should be noted that East-
East-West links are included in South TIE flooding (except at the ToF West links are included in South TIE flooding (except at the ToF
level); those TIEs need to be flooded to satisfy algorithms in level); those TIEs need to be flooded to satisfy the algorithms
Section 6.4. In that way nodes at same level can learn about each described in Section 6.4. In that way, nodes at same level can learn
other using without a lower level except in case of leaf level. The about each other without using a lower level except in case of leaf
precise, normative flooding scopes are given in Table 3. Those rules level. The precise, normative flooding scopes are given in Table 3.
also govern what SHOULD be included in TIDEs on the adjacency. Those rules also govern what SHOULD be included in TIDEs on the
Again, East-West flooding scopes are identical to South flooding adjacency. Again, East-West flooding scopes are identical to
scopes except in case of ToF East-West links (rings) which are southern flooding scopes, except in case of ToF East-West links
basically performing northbound flooding. (rings), which are basically performing northbound flooding.
Node South TIE "south reflection" enables support of positive Node South TIE "south reflection" enables support of positive
disaggregation on failures as described in Section 6.5 and flooding disaggregation on failures, as described in Section 6.5, and flooding
reduction in Section 6.3.9. reduction, as described in Section 6.3.9.
+===========+======================+==============+=================+ +===========+======================+==============+=================+
| Type / | South | North | East-West | | Type / | South | North | East-West |
| Direction | | | | | Direction | | | |
+===========+======================+==============+=================+ +===========+======================+==============+=================+
| Node | flood if level of | flood if | flood only if | | Node | flood if the level | flood if the | flood only if |
| South TIE | originator is | level of | this node is | | South TIE | of the originator | level of the | this node is |
| | equal to this | originator | not ToF | | | is equal to this | originator | not ToF |
| | node | is higher | | | | node | is higher | |
| | | than this | | | | | than this | |
| | | node | | | | | node | |
+-----------+----------------------+--------------+-----------------+ +-----------+----------------------+--------------+-----------------+
| non-Node | flood self- | flood only | flood only if | | non-Node | flood self- | flood only | flood only if |
| South TIE | originated only | if neighbor | self-originated | | South TIE | originated only | if the | it is self- |
| | | is | and this node | | | | neighbor is | originated and |
| | | originator | is not ToF | | | | the | this node is |
| | | originator | not ToF |
| | | of TIE | | | | | of TIE | |
+-----------+----------------------+--------------+-----------------+ +-----------+----------------------+--------------+-----------------+
| all North | never flood | flood always | flood only if | | all North | never flood | flood always | flood only if |
| TIEs | | | this node is | | TIEs | | | this node is |
| | | | ToF | | | | | ToF |
+-----------+----------------------+--------------+-----------------+ +-----------+----------------------+--------------+-----------------+
| TIDE | include at least | include at | if this node is | | TIDE | include at least | include at | if this node is |
| | all non-self | least all | ToF then | | | all non-self- | least all | ToF, then |
| | originated North | Node South | include all | | | originated North | Node South | include all |
| | TIE headers and | TIEs and all | North TIEs, | | | TIE headers and | TIEs and all | North TIEs; |
| | self-originated | South TIEs | otherwise only | | | self-originated | South TIEs | otherwise, only |
| | South TIE headers | originated | self-originated | | | South TIE headers | originated | include self- |
| | and Node South | by peer and | TIEs | | | and Node South TIEs | by a peer | originated TIEs |
| | TIEs of nodes at | all North | | | | of nodes at same | and all | |
| | same level | TIEs | | | | level | North TIEs | |
+-----------+----------------------+--------------+-----------------+ +-----------+----------------------+--------------+-----------------+
| TIRE as | request all North | request all | if this node is | | TIRE as | request all North | request all | if this node is |
| Request | TIEs and all | South TIEs | ToF then apply | | Request | TIEs and all peer's | South TIEs | ToF, then apply |
| | peer's self- | | North scope | | | self-originated | | north scope |
| | originated TIEs | | rules, | | | TIEs and all Node | | rules; |
| | and all Node | | otherwise South | | | South TIEs | | otherwise, |
| | South TIEs | | scope rules | | | | | apply south |
| | | | scope rules |
+-----------+----------------------+--------------+-----------------+ +-----------+----------------------+--------------+-----------------+
| TIRE as | Ack all received | Ack all | Ack all | | TIRE as | Ack all received | Ack all | Ack all |
| Ack | TIEs | received | received TIEs | | Ack | TIEs | received | received TIEs |
| | | TIEs | | | | | TIEs | |
+-----------+----------------------+--------------+-----------------+ +-----------+----------------------+--------------+-----------------+
Table 3: Normative Flooding Scopes Table 3: Normative Flooding Scopes
If the TIDE includes additional TIE headers beside the ones If the TIDE includes additional TIE headers beside the ones
specified, the receiving neighbor must apply the corresponding filter specified, the receiving neighbor must apply the corresponding filter
skipping to change at page 69, line 49 skipping to change at line 3079
+------------+----------+-------------------------------------------+ +------------+----------+-------------------------------------------+
| ToF 21 | Spine | ToF 21 South TIEs | | ToF 21 | Spine | ToF 21 South TIEs |
| | 121 | | | | 121 | |
+------------+----------+-------------------------------------------+ +------------+----------+-------------------------------------------+
| ToF 21 | Spine | ToF 21 South TIEs | | ToF 21 | Spine | ToF 21 South TIEs |
| | 122 | | | | 122 | |
+------------+----------+-------------------------------------------+ +------------+----------+-------------------------------------------+
| ... | ... | ... | | ... | ... | ... |
+------------+----------+-------------------------------------------+ +------------+----------+-------------------------------------------+
Table 4: Flooding some TIEs from example topology Table 4: Flooding Some TIEs from Example Topology
6.3.5. RAIN: RIFT Adjacency Inrush Notification 6.3.5. RAIN: RIFT Adjacency Inrush Notification
The optional RIFT Adjacency Inrush Notification (RAIN) mechanism The optional RIFT Adjacency Inrush Notification (RAIN) mechanism
helps to prevent adjacencies from being overwhelmed by flooding on helps to prevent adjacencies from being overwhelmed by flooding on
restart or bring-up with many southbound neighbors. A node MAY set restart or bring-up with many southbound neighbors. In its LIEs, a
in its LIEs the corresponding _you_are_sending_too_quickly_ flag to node MAY set the corresponding _you_are_sending_too_quickly_ flag to
indicate to the neighbor that it SHOULD flood Node TIEs with normal indicate to the neighbor that it SHOULD flood Node TIEs with normal
speed and significantly slow down the flooding of any other TIEs. speed and significantly slow down the flooding of any other TIEs.
The flag SHOULD be set only in the southbound direction. The The flag SHOULD be set only in the southbound direction. The
receiving node SHOULD accommodate the request to lessen the flooding receiving node SHOULD accommodate the request to lessen the flooding
load on the affected node if south of the sender and should ignore load on the affected node if it is south of the sender and should
the indication if north of the sender. ignore the indication if it is north of the sender.
The distribution of Node TIEs at normal speed even at high load The distribution of Node TIEs at normal speed, even at high load,
guarantees correct behavior of algorithms like disaggregation or guarantees correct behavior of algorithms like disaggregation or
default route origination. Furthermore though, the use of this bit default route origination. Furthermore though, the use of this bit
presents an inherent trade-off between processing load and presents an inherent trade-off between processing load and
convergence speed since significantly slowing down flooding of convergence speed since significantly slowing down flooding of
northbound prefixes from neighbors for an extended time will lead to northbound prefixes from neighbors for an extended time will lead to
traffic losses. traffic losses.
6.3.6. Initial and Periodic Database Synchronization 6.3.6. Initial and Periodic Database Synchronization
The initial exchange of RIFT includes periodic TIDE exchanges that The initial exchange of RIFT includes periodic TIDE exchanges that
contain description of the link state database and TIREs which contain descriptions of the link state database and TIREs, which
perform the function of requesting unknown TIEs as well as confirming perform the function of requesting unknown TIEs as well as confirming
reception of flooded TIEs. The content of TIDEs and TIREs is the reception of flooded TIEs. The content of TIDEs and TIREs is
governed by Table 3. governed by Table 3.
6.3.7. Purging and Roll-Overs 6.3.7. Purging and Rollovers
When a node exits the network, if "unpurged", residual stale TIEs may When a node exits in the network, if "unpurged", residual stale TIEs
exist in the network until their lifetimes expire (which in case of may exist in the network until their lifetimes expire (which in case
RIFT is by default a rather long period to prevent ongoing re- of RIFT is by default a rather long period to prevent ongoing
origination of TIEs in very large topologies). RIFT does not have a reorigination of TIEs in very large topologies). RIFT does not have
"purging mechanism" based on sending specialized "purge" packets. In a "purging mechanism" based on sending specialized "purge" packets.
other routing protocols such a mechanism has proven to be complex and In other routing protocols, such a mechanism has proven to be complex
fragile based on many years of experience. RIFT simply issues a new, and fragile based on many years of experience. RIFT simply issues a
i.e., higher sequence number, empty version of the TIE with a short new, i.e., higher sequence number, empty version of the TIE with a
lifetime given by the _purge_lifetime_ constant and relies on each short lifetime given by the _purge_lifetime_ constant and relies on
node to age out and delete each TIE copy independently. Abundant each node to age out and delete each TIE copy independently.
amounts of memory are available today even on low-end platforms and Abundant amounts of memory are available today, even on low-end
hence keeping those relatively short-lived extra copies for a while platforms, and hence, keeping those relatively short-lived extra
is acceptable. The information will age out and in the meantime all copies for a while is acceptable. The information will age out and,
computations will deliver correct results if a node leaves the in the meantime, all computations will deliver correct results if a
network due to the new information distributed by its adjacent nodes node leaves the network due to the new information distributed by its
breaking bi-directional connectivity checks in different adjacent nodes breaking bidirectional connectivity checks in
computations. different computations.
Once a RIFT node issues a TIE with an ID, it SHOULD preserve the ID Once a RIFT node issues a TIE with an ID, it SHOULD preserve the ID
as long as feasible (also when the protocol restarts), even if the as long as feasible (also when the protocol restarts), even if the
TIE looses all content. The re-advertisement of an empty TIE TIE looses all content. The re-advertisement of an empty TIE
fulfills the purpose of purging any information advertised in fulfills the purpose of purging any information advertised in
previous versions. The originator is free to not re-originate the previous versions. The originator is free to not reoriginate the
corresponding empty TIE again or originate an empty TIE with corresponding empty TIE again or originate an empty TIE with a
relatively short lifetime to prevent large number of long-lived empty relatively short lifetime to prevent a large number of long-lived
stubs polluting the network. Each node MUST time out and clean up empty stubs polluting the network. Each node MUST time out and clean
the corresponding empty TIEs independently. up the corresponding empty TIEs independently.
Upon restart a node MUST be prepared to receive TIEs with its own Upon restart, a node MUST be prepared to receive TIEs with its own
System ID and supersede them with equivalent, newly generated, empty System ID and supersede them with equivalent, newly generated, empty
TIEs with a higher sequence number. As above, the lifetime can be TIEs with a higher sequence number. As above, the lifetime can be
relatively short since it only needs to exceed the necessary relatively short since it only needs to exceed the necessary
propagation and processing delay by all the nodes that are within the propagation and processing delay by all the nodes that are within the
TIE's flooding scope. TIE's flooding scope.
TIE sequence numbers are rolled over using the method described in TIE sequence numbers are rolled over using the method described in
Appendix A . First sequence number of any spontaneously originated Appendix A . The first sequence number of any spontaneously
TIE (i.e. not originated to override a detected older copy in the originated TIE (i.e., not originated to override a detected older
network) MUST be a reasonably unpredictable random number (for copy in the network) MUST be a reasonably unpredictable random number
example [RFC4086]) in the interval [0, 2^30-1] which will prevent (for example, [RFC4086]) in the interval [0, 2^30-1], which will
otherwise identical TIE headers to remain "stuck" in the network with prevent otherwise identical TIE headers to remain "stuck" in the
content different from TIE originated after reboot. In traditional network with content different from the TIE originated after reboot.
link-state protocols this is delegated to a 16-bit checksum on packet In traditional link-state protocols, this is delegated to a 16-bit
content. RIFT avoids this design due to the CPU burden presented by checksum on packet content. RIFT avoids this design due to the CPU
computation of such checksums and additional complications tied to burden presented by computation of such checksums and additional
the fact that the checksum must be "patched" into the packet after complications tied to the fact that the checksum must be "patched"
the generation of the content, a difficult proposition in binary into the packet after the generation of the content, which is a
hand-crafted formats already and highly incompatible with model- difficult proposition in binary, hand-crafted formats already and
based, serialized formats. The sequence number space is hence highly incompatible with model-based, serialized formats. The
consciously chosen to be 64-bits wide to make the occurrence of a TIE sequence number space is hence consciously chosen to be 64-bits wide
with same sequence number but different content as much or even more to make the occurrence of a TIE with the same sequence number but
unlikely than the checksum method. To emulate the "checksum different content as much or even more unlikely than the checksum
behavior" an implementation could choose to compute a 64-bit checksum method. To emulate the "checksum behavior", an implementation could
or hash function over the TIE content and use that as part of the choose to compute a 64-bit checksum or hash function over the TIE
first sequence number after reboot. content and use that as part of the first sequence number after
reboot.
6.3.8. Southbound Default Route Origination 6.3.8. Southbound Default Route Origination
Under certain conditions nodes issue a default route in their South Under certain conditions, nodes issue a default route in their South
Prefix TIEs with costs as computed in Section 6.8.7.1. Prefix TIEs with costs as computed in Section 6.8.7.1.
A node X that A node X that
1. is *not* overloaded *and* 1. is *not* overloaded *and*
2. has southbound or East-West adjacencies 2. has southbound or East-West adjacencies
SHOULD originate in its south prefix TIE such a default route if and
SHOULD originate such a default route in its south prefix TIE if and
only if only if
1. all other nodes at X's' level are overloaded *or* 1. all other nodes at X's' level are overloaded,
2. all other nodes at X's' level have NO northbound adjacencies *or* 2. all other nodes at X's' level have NO northbound adjacencies,
*or*
3. X has computed reachability to a default route during N-SPF. 3. X has computed reachability to a default route during N-SPF.
The term "all other nodes at X's' level" describes obviously just the The term "all other nodes at X's' level " obviously describes just
nodes at the same level in the PoD with a viable lower level the nodes at the same level in the PoD with a viable lower level
(otherwise the Node South TIEs cannot be reflected. The nodes in PoD (otherwise, the Node South TIEs cannot be reflected; the nodes in PoD
1 and PoD 2 are "invisible" to each other). 1 and PoD 2 are "invisible" to each other).
A node originating a southbound default route SHOULD install a A node originating a southbound default route SHOULD install a
default discard route if it did not compute a default route during default discard route if it did not compute a default route during
N-SPF. This basically means that the top of the fabric will drop N-SPF. This basically means that the top of the fabric will drop
traffic for unreachable addresses. traffic for unreachable addresses.
6.3.9. Northbound TIE Flooding Reduction 6.3.9. Northbound TIE Flooding Reduction
RIFT chooses only a subset of northbound nodes to propagate flooding RIFT chooses only a subset of northbound nodes to propagate flooding
and with that both balances it (to prevent 'hot' flooding links) and, with that, both balances it (to prevent "hot" flooding links)
across the fabric as well as reduces its volume. The solution is across the fabric as well as reduces its volume. The solution is
based on several principles: based on several principles:
1. a node MUST flood self-originated North TIEs to all the reachable 1. a node MUST flood self-originated North TIEs to all the reachable
nodes at the level above which is called the node's "parents"; nodes at the level above, which is called the node's "parents";
2. it is typically not necessary that all parents reflood the North 2. it is typically not necessary that all parents reflood the North
TIEs to achieve a complete flooding of all the reachable nodes TIEs to achieve a complete flooding of all the reachable nodes
two levels above which we call the node's "grandparents"; two levels above, which we call the node's "grandparents";
3. to control the volume of its flooding two hops North and yet keep 3. to control the volume of its flooding two hops north and yet keep
it robust enough, it is advantageous for a node to select a it robust enough, it is advantageous for a node to select a
subset of its parents as "Flood Repeaters" (FRs), which when subset of its parents as "Flood Repeaters" (FRs), which when
combined, deliver two or more copies of its flooding to all of combined, deliver two or more copies of its flooding to all of
its parents, i.e. the originating node's grandparents; its parents, i.e., the originating node's grandparents;
4. nodes at the same level do *not* have to agree on a specific 4. nodes at the same level do *not* have to agree on a specific
algorithm to select the FRs, but overall load balancing should be algorithm to select the FRs, but overall load balancing should be
achieved so that different nodes at the same level should tend to achieved so that different nodes at the same level should tend to
select different parents as FRs (consideration of possible select different parents as FRs (consideration of possible
strategies in an unrelated but similar field can be found in strategies in an unrelated but similar field can be found in
[RFC2991]); [RFC2991]);
5. there are usually many solutions to the problem of finding a set 5. there are usually many solutions to the problem of finding a set
of FRs for a given node; the problem of finding the minimal set of FRs for a given node; the problem of finding the minimal set
is (similar to) a NP-Complete problem and a globally optimal set is (similar to) an NP-Complete problem, and a globally optimal
may not be the minimal one if load-balancing with other nodes is set may not be the minimal one if load balancing with other nodes
an important consideration; is an important consideration;
6. it is expected that there will often exist sets of equivalent 6. it is expected that sets of equivalent nodes at a level L will
nodes at a level L, defined as having a common set of parents at often exist, defined as having a common set of parents at L+1.
L+1. Applying this observation at both L and L+1, an algorithm Applying this observation at both L and L+1, an algorithm may
may attempt to split the larger problem in a sum of smaller attempt to split the larger problem in a sum of smaller, separate
separate problems; problems; and
7. it is expected that there will be from time to time a broken link 7. it is expected that there will be a broken link between a parent
between a parent and a grandparent, and in that case the parent and a grandparent from time to time, and in that case, the parent
is probably a poor FR due to its lower reliability. An algorithm is probably a poor FR due to its lower reliability. An algorithm
may attempt to eliminate parents with broken northbound may attempt to eliminate parents with broken northbound
adjacencies first in order to reduce the number of FRs. Albeit adjacencies first in order to reduce the number of FRs. Albeit
it could be argued that relying on higher fanout FRs will slow it could be argued that relying on higher fanout FRs will slow
flooding due to higher replication, load reliability of FR's flooding due to higher replication, load reliability of FR's
links is likely a more pressing concern. links is likely a more pressing concern.
In a fully connected Clos Network, this means that a node selects one In a fully connected Clos network, this means that a node selects one
arbitrary parent as FR and then a second one for redundancy. The arbitrary parent as the FR and then a second one for redundancy. The
computation can be relatively simple and completely distributed computation can be relatively simple and completely distributed
without any need for synchronization among nodes. In a "PoD" without any need for synchronization among nodes. In a "PoD"
structure, where the Level L+2 is partitioned into silos of structure, where the level L+2 is partitioned into silos of
equivalent grandparents that are only reachable from respective equivalent grandparents that are only reachable from respective
parents, this means treating each silo as a fully connected Clos parents, this means treating each silo as a fully connected Clos
Network and solving the problem within the silo. network and solving the problem within the silo.
In terms of signaling, a node has enough information to select its In terms of signaling, a node has enough information to select its
set of FRs; this information is derived from the node's parents' Node set of FRs; this information is derived from the node's parents' Node
South TIEs, which indicate the parent's reachable northbound South TIEs, which indicate the parent's reachable northbound
adjacencies to its own parents (the node's grandparents). A node may adjacencies to its own parents (the node's grandparents). A node may
send a LIE to a northbound neighbor with the optional boolean field send a LIE to a northbound neighbor with the optional boolean field
_you_are_flood_repeater_ set to false, to indicate that the _you_are_flood_repeater_ set to false to indicate that the northbound
northbound neighbor is not a flood repeater for the node that sent neighbor is not a flood repeater for the node that sent the LIE. In
the LIE. In that case the northbound neighbor SHOULD NOT reflood that case, the northbound neighbor SHOULD NOT reflood northbound TIEs
northbound TIEs received from the node that sent the LIE. If the received from the node that sent the LIE. If
_you_are_flood_repeater_ is absent or if _you_are_flood_repeater_ is _you_are_flood_repeater_ is absent or _you_are_flood_repeater_ is set
set to true, then the northbound neighbor is a flood repeater for the to true, then the northbound neighbor is a flood repeater for the
node that sent the LIE and MUST reflood northbound TIEs received from node that sent the LIE and MUST reflood northbound TIEs received from
that node. The element _you_are_flood_repeater_ MUST be ignored if that node. The element _you_are_flood_repeater_ MUST be ignored if
received from a northbound adjacency. received from a northbound adjacency.
This specification provides a simple default algorithm that SHOULD be This specification provides a simple default algorithm that SHOULD be
implemented and used by default on every RIFT node. implemented and used by default on every RIFT node.
* let |NA(Node) be the set of Northbound adjacencies of node Node * let |NA(Node) be the set of northbound adjacencies of node Node
and CN(Node) be the cardinality of |NA(Node); and CN(Node) be the cardinality of |NA(Node);
* let |SA(Node) be the set of Southbound adjacencies of node Node * let |SA(Node) be the set of southbound adjacencies of node Node
and CS(Node) be the cardinality of |SA(Node); and CS(Node) be the cardinality of |SA(Node);
* let |P(Node) be the set of node Node's parents; * let |P(Node) be the set of node Node's parents;
* let |G(Node) be the set of node Node's grandparents. Observe * let |G(Node) be the set of node Node's grandparents. Observe
that |G(Node) = |P(|P(Node)); that |G(Node) = |P(|P(Node));
* let N be the child node at level L computing a set of FR; * let N be the child node at level L computing a set of FRs;
* let P be a node at level L+1 and a parent node of N, i.e. bi- * let P be a node at level L+1 and a parent node of N, i.e.,
directionally reachable over adjacency ADJ(N, P); bidirectionally reachable over adjacency ADJ(N, P);
* let G be a grandparent node of N, reachable transitively via a * let G be a grandparent node of N, reachable transitively via a
parent P over adjacencies ADJ(N, P) and ADJ(P, G). Observe that N parent P over adjacencies ADJ(N, P) and ADJ(P, G). Observe that N
does not have enough information to check bidirectional does not have enough information to check bidirectional
reachability of ADJ(P, G); reachability of ADJ(P, G);
* let R be a redundancy constant integer; a value of 2 or higher for * let R be a redundancy constant integer; a value of 2 or higher for
R is RECOMMENDED; R is RECOMMENDED;
* let S be a similarity constant integer; a value in range 0 .. 2 * let S be a similarly constant integer; a value in range 0 .. 2 for
for S is RECOMMENDED, the value of 1 SHOULD be used. Two S is RECOMMENDED, and the value of 1 SHOULD be used. Two
cardinalities are considered as equivalent if their absolute cardinalities are considered as equivalent if their absolute
difference is less than or equal to S, i.e. |a-b|<=S. difference is less than or equal to S, i.e., |a-b|<=S; and
* let RND be a 64-bit random number (for example [RFC4086]) * let RND be a 64-bit random number (for example, as described in
generated by the system once on startup. [RFC4086]) generated by the system once on startup.
The algorithm consists of the following steps: The algorithm consists of the following steps:
1. Derive a 64-bits number by XOR'ing 'N's System ID with RND. 1. Derive a 64-bit number by XORing N's System ID with RND.
2. Derive a 16-bits pseudo-random unsigned integer PR(N) from the 2. Derive a 16-bit pseudo-random unsigned integer PR(N) from the
resulting 64-bits number by splitting it in 16-bits-long words resulting 64-bit number by splitting it into 16-bit-long words
W1, W2, W3, W4 (where W1 are the least significant 16 bits of the W1, W2, W3, W4 (where W1 are the least significant 16 bits of the
64-bits number, and W4 are the most significant 16 bits) and then 64-bit number, and W4 are the most significant 16 bits) and then
XOR'ing the circularly shifted resulting words together: XORing the circularly shifted resulting words together:
A. (W1<<1) xor (W2<<2) xor (W3<<3) xor (W4<<4);
where << is the circular shift operator. (W1<<1) xor (W2<<2) xor (W3<<3) xor (W4<<4); where << is the
circular shift operator.
3. Sort the parents by decreasing number of northbound adjacencies 3. Sort the parents by decreasing number of northbound adjacencies
(using decreasing System ID of the parent as tie-breaker): (using decreasing System ID of the parent as a tie-breaker):
sort |P(N) by decreasing CN(P), for all P in |P(N), as ordered sort |P(N) by decreasing CN(P), for all P in |P(N), as the
array |A(N) ordered array |A(N)
4. Partition |A(N) in subarrays |A_k(N) of parents with equivalent 4. Partition |A(N) in subarrays |A_k(N) of parents with equivalent
cardinality of northbound adjacencies (in other words with cardinality of northbound adjacencies (in other words, with
equivalent number of grandparents they can reach): equivalent number of grandparents they can reach):
A. set k=0; // k is the ID of the subarrray a. set k=0; // k is the ID of the subarray
B. set i=0; b. set i=0;
C. while i < CN(N) do c. while i < CN(N) do the following:
i) set j=i; i. set j=i;
ii) while i < CN(N) and CN(|A(N)[j]) - CN(|A(N)[i]) <= S ii. while i < CN(N) and CN(|A(N)[j]) - CN(|A(N)[i]) <= S:
a. place |A(N)[i] in |A_k(N) // abstract action, maybe 1. place |A(N)[i] in |A_k(N) // abstract action, maybe
noop noop
b. set i=i+1; 2. set i=i+1;
iii) /* At this point j is the index in |A(N) of the first iii. /* At this point, j is the index in |A(N) of the first
member of |A_k(N) and (i-j) is C_k(N) defined as the member of |A_k(N) and (i-j) is C_k(N) defined as the
cardinality of |A_k(N) */ cardinality of |A_k(N). */
set k=k+1; set k=k+1.
/* At this point k is the total number of subarrays, initialized /* At this point, k is the total number of subarrays, initialized
for the shuffling operation below */ for the shuffling operation below. */
5. shuffle individually each subarrays |A_k(N) of cardinality C_k(N) 5. Shuffle each subarrays |A_k(N) of cardinality C_k(N) within |A(N)
within |A(N) using the Durstenfeld variation of Fisher-Yates individually using the Durstenfeld variation of the Fisher-Yates
algorithm that depends on N's System ID: algorithm that depends on N's System ID:
A. while k > 0 do a. while k > 0 do the following:
i) for i from C_k(N)-1 to 1 decrementing by 1 do i. for i from C_k(N)-1 to 1 decrementing by 1, do the
following:
a. set j to PR(N) modulo i; 1. set j to PR(N) modulo i;
b. exchange |A_k[j] and |A_k[i]; 2. exchange |A_k[j] and |A_k[i];
ii) set k=k-1; ii. set k=k-1.
6. For each grandparent G, initialize a counter c(G) with the number 6. For each grandparent G, initialize a counter c(G) with the number
of its south-bound adjacencies to elected flood repeaters (which of its southbound adjacencies to elected flood repeaters (which
is initially zero): is initially zero):
A. for each G in |G(N) set c(G) = 0; a. for each G in |G(N), set c(G) = 0.
7. Finally keep as FRs only parents that are needed to maintain the 7. Finally, only keep FRs as parents that are needed to maintain the
number of adjacencies between the FRs and any grandparent G equal number of adjacencies between the FRs and any grandparent G equal
or above the redundancy constant R: or above the redundancy constant R:
A. for each P in reshuffled |A(N); a. for each P in reshuffled |A(N):
i) if there exists an adjacency ADJ(P, G) in |NA(P) such i. if there exists an adjacency ADJ(P, G) in |NA(P) such
that c(G) < R then that c(G) < R, then
a. place P in FR set; 1. place P in FR set;
b. for all adjacencies ADJ(P, G') in |NA(P) increment 2. for all adjacencies ADJ(P, G') in |NA(P) increment
c(G') c(G')
B. If any c(G) is still < R, it was not possible to elect a set 8. If any c(G) is still < R, it was not possible to elect a set of
of FRs that covers all grandparents with redundancy R FRs that covers all grandparents with redundancy R
Additional rules for flooding reduction: Additional rules for flooding reduction:
1. The algorithm MUST be re-evaluated by a node on every change of 1. The algorithm MUST be re-evaluated by a node on every change of
local adjacencies or reception of a parent South TIE with changed local adjacencies or reception of a parent South TIE with changed
adjacencies. A node MAY apply a hysteresis to prevent excessive adjacencies. A node MAY apply a hysteresis to prevent an
amount of computation during periods of network instability just excessive amount of computation during periods of network
like in the case of reachability computation. instability just like in the case of reachability computation.
2. Upon a change of the flood repeater set, a node SHOULD send out 2. Upon a change of the flood repeater set, a node SHOULD send out
LIEs that grant flood repeater status to newly promoted nodes LIEs that grant flood repeater status to newly promoted nodes
before it sends LIEs that revoke the status to the nodes that before it sends LIEs that revoke the status to the nodes that
have been newly demoted. This is done to prevent transient have been newly demoted. This is done to prevent transient
behavior where the full coverage of grandparents is not behavior where the full coverage of grandparents is not
guaranteed. Such a condition is sometimes unavoidable in case of guaranteed. Such a condition is sometimes unavoidable in case of
lost LIEs but it will correct itself though at possible transient lost LIEs, but it will correct itself at possible transient
reduction in flooding propagation speeds. The election can use reduction in flooding propagation speeds. The election can use
the LIE FSM _FloodLeadersChanged_ event to notify LIE FSMs of the LIE FSM _FloodLeadersChanged_ event to notify LIE FSMs of the
necessity to update the sent LIEs. necessity to update the sent LIEs.
3. A node MUST always flood its self-originated TIEs to all its 3. A node MUST always flood its self-originated TIEs to all its
neighbors. neighbors.
4. A node receiving a TIE originated by a node for which it is not a 4. A node receiving a TIE originated by a node for which it is not a
flood repeater SHOULD NOT reflood such TIEs to its neighbors flood repeater SHOULD NOT reflood such TIEs to its neighbors,
except for rules in Section 6.3.9, Paragraph 10, Item 6. except for the rules described in Section 6.3.9, Paragraph 10,
Item 6.
5. The indication of flood reduction capability MUST be carried in 5. The indication of flood reduction capability MUST be carried in
the Node TIEs in the _flood_reduction_ element and MAY be used to the Node TIEs in the _flood_reduction_ element and MAY be used to
optimize the algorithm to account for nodes that will flood optimize the algorithm to account for nodes that will flood
regardless. regardless.
6. A node generates TIDEs as usual but when receiving TIREs or TIDEs 6. A node generates TIDEs as usual, but when receiving TIREs or
resulting in requests for a TIE of which the newest received copy TIDEs resulting in requests for a TIE of which the newest
came on an adjacency where the node was not flood repeater it received copy came on an adjacency where the node was not a flood
SHOULD ignore such requests on first and only first request. repeater, it SHOULD ignore such requests on first and only first
Normally, the nodes that received the TIEs as flooding repeaters request. Normally, the nodes that received the TIEs as flooding
should satisfy the requesting node and with that no further TIREs repeaters should satisfy the requesting node and, with that, no
for such TIEs will be generated. Otherwise, the next set of further TIREs for such TIEs will be generated. Otherwise, the
TIDEs and TIREs MUST lead to flooding independent of the flood next set of TIDEs and TIREs MUST lead to flooding independent of
repeater status. This solves a very difficult incast problem on the flood repeater status. This solves a very difficult "incast"
nodes restarting with a very wide fanout, especially northbound. problem on nodes restarting with a very wide fanout, especially
To retrieve the full database they often end up processing many northbound. To retrieve the full database, they often end up
in-rushing copies whereas this approach load-balances the processing many inrushing copies, whereas this approach load
incoming database between adjacent nodes and flood repeaters and balances the incoming database between adjacent nodes and flood
should guarantee that two copies are sent by different nodes to repeaters and should guarantee that two copies are sent by
ensure against any losses. different nodes to ensure against any losses.
6.3.10. Special Considerations 6.3.10. Special Considerations
First, due to the distributed, asynchronous nature of ZTP, it can First, due to the distributed, asynchronous nature of ZTP, it can
create temporary convergence anomalies where nodes at higher levels create temporary convergence anomalies where nodes at higher levels
of the fabric temporarily become lower than where they ultimately of the fabric temporarily become lower than where they ultimately
belong. Since flooding can begin before ZTP is "finished" and in belong. Since flooding can begin before ZTP is "finished" and in
fact must do so given there is no global termination criteria for the fact must do so given there is no global termination criteria for the
unsychronized ZTP algorithm, information may end up temporarily in unsynchronized ZTP algorithm, information may temporarily end up in
wrong layers. A special clause when changing level takes care of wrong layers. A special clause when changing level takes care of
that. that.
More difficult is a condition where a node (e.g. a leaf) floods a TIE More difficult is a condition where a node (e.g., a leaf) floods a
north towards its grandparent, then its parent reboots, partitioning TIE north towards its grandparent, then its parent reboots,
the grandparent from leaf directly and then the leaf itself reboots. partitioning the grandparent from the leaf directly, and then the
That can leave the grandparent holding the "primary copy" of the leaf itself reboots. That can leave the grandparent holding the
leaf's TIE. Normally this condition is resolved easily by the leaf "primary copy" of the leaf's TIE. Normally, this condition is
re-originating its TIE with a higher sequence number than it notices resolved easily by the leaf reoriginating its TIE with a higher
in the northbound TIEs, here however, when the parent comes back it sequence number than it notices in the northbound TIEs; here however,
won't be able to obtain leaf's North TIE from the grandparent easily when the parent comes back, it won't be able to obtain the leaf's
and with that the leaf may not issue the TIE with a higher sequence North TIE from the grandparent easily, and with that, the leaf may
number that can reach the grandparent for a long time. Flooding not issue the TIE with a higher sequence number that can reach the
procedures are extended to deal with the problem by the means of grandparent for a long time. Flooding procedures are extended to
special clauses that override the database of a lower level with deal with the problem by the means of special clauses that override
headers of newer TIEs received in TIDEs coming from the north. Those the database of a lower level with headers of newer TIEs received in
headers are then propagated southbound towards the leaf to cause it TIDEs coming from the north. Those headers are then propagated
to originate a higher sequence number of the TIE effectively southbound towards the leaf to cause it to originate a higher
refreshing it all the way up to ToF. sequence number of the TIE, effectively refreshing it all the way up
to ToF.
6.4. Reachability Computation 6.4. Reachability Computation
A node has three possible sources of relevant information for A node has three possible sources of relevant information for
reachability computation. A node knows the full topology south of it reachability computation. A node knows the full topology south of it
from the received North Node TIEs or alternately north of it from the from the received North Node TIEs or alternately north of it from the
South Node TIEs. A node has the set of prefixes with their South Node TIEs. A node has the set of prefixes with their
associated distances and bandwidths from corresponding prefix TIEs. associated distances and bandwidths from corresponding prefix TIEs.
To compute prefix reachability, a node runs conceptually a northbound To compute prefix reachability, a node conceptually runs a northbound
and a southbound SPF. N-SPF and S-SPF notation denotes here the and a southbound SPF. Here, N-SPF and S-SPF notation denotes the
direction in which the computation front is progressing. direction in which the computation front is progressing.
Since neither computation can "loop", it is possible to compute non- Since neither computation can "loop", it is possible to compute non-
equal-cost or even k-shortest paths [EPPSTEIN] and "saturate" the equal costs or even k-shortest paths [EPPSTEIN] and "saturate" the
fabric to the extent desired. This specification however uses fabric to the extent desired. This specification however uses
simple, familiar SPF algorithms and concepts as example due to their simple, familiar SPF algorithms and concepts as examples due to their
prevalence in today's routing. prevalence in today's routing.
For reachability computation purposes, RIFT considers all parallel For reachability computation purposes, RIFT considers all parallel
links between two nodes to be of the same cost advertised in the links between two nodes to be of the same cost advertised in the
_cost_ element of _NodeNeighborsTIEElement_. In case the neighbor has _cost_ element of _NodeNeighborsTIEElement_. In case the neighbor has
multiple parallel links at different cost, the largest distance multiple parallel links at different costs, the largest distance
(highest numerical value) MUST be advertised. Given the range of (highest numerical value) MUST be advertised. Given the range of
thrift encodings, _infinite_distance_ is defined as the largest non- Thrift encodings, _infinite_distance_ is defined as the largest non-
negative _MetricType_. Any link with metric larger than that (i.e. negative _MetricType_. Any link with a metric larger than that (i.e.,
negative MetricType) MUST be ignored in computations. Any link with the negative MetricType) MUST be ignored in computations. Any link
metric set to _invalid_distance_ MUST also be ignored in computation. with the metric set to _invalid_distance_ MUST also be ignored in
In case of a negatively distributed prefix the metric attribute MUST computation. In case of a negatively distributed prefix, the metric
be set to _infinite_distance_ by the originator and it MUST be attribute MUST be set to _infinite_distance_ by the originator, and
ignored by all nodes during computation except for the purpose of it MUST be ignored by all nodes during computation, except for the
determining transitive propagation and building the corresponding purpose of determining transitive propagation and building the
routing table. corresponding routing table.
A prefix can carry the _directly_attached_ attribute to indicate that A prefix can carry the _directly_attached_ attribute to indicate that
the prefix is directly attached, i.e., should be routed to even if the prefix is directly attached, i.e., should be routed to even if
the node is in overload. In case of a negatively distributed prefix the node is in overload. In case of a negatively distributed prefix,
this attribute MUST NOT be included by the originator and it MUST be this attribute MUST NOT be included by the originator, and it MUST be
ignored by all nodes during SPF computation. If a prefix is locally ignored by all nodes during SPF computation. If a prefix is locally
originated the attribute _from_link_ can indicate the interface to originated, the attribute _from_link_ can indicate the interface to
which the address belongs to. In case of a negatively distributed which the address belongs to. In case of a negatively distributed
prefix this attribute MUST NOT be included by the originator and it prefix, this attribute MUST NOT be included by the originator, and it
MUST be ignored by all nodes during computation. A prefix can also MUST be ignored by all nodes during computation. A prefix can also
carry the _loopback_ attribute to indicate the said property. carry the _loopback_ attribute to indicate the said property.
Prefixes are carried in different types of TIEs indicating their Prefixes are carried in different types of TIEs indicating their
type. For same prefix being included in different TIE types tie- type. For the same prefix being included in different TIE types,
breaking is performed according to Section 6.8.1. If the same prefix tie-breaking is performed according to Section 6.8.1. If the same
is included multiple times in multiple TIEs of the same type prefix is included multiple times in multiple TIEs of the same type
originating at the same node the resulting behavior is unspecified. originating at the same node, the resulting behavior is unspecified.
6.4.1. Northbound Reachability SPF 6.4.1. Northbound Reachability SPF
N-SPF MUST use exclusively northbound and East-West adjacencies in N-SPF MUST use exclusively northbound and East-West adjacencies in
the computing node's node North TIEs (since if the node is a leaf it the computing node's node North TIEs (since if the node is a leaf, it
may not have generated a Node South TIE) when starting SPF. Observe may not have generated a Node South TIE) when starting SPF. Observe
that N-SPF is really just a one hop variety since Node South TIEs are that N-SPF is really just a one-hop variety since Node South TIEs are
not re-flooded southbound beyond a single level (or East-West) and not reflooded southbound beyond a single level (or East-West), and
with that the computation cannot progress beyond adjacent nodes. with that, the computation cannot progress beyond adjacent nodes.
Once progressing, the computation uses the next higher level's Node Once progressing, the computation uses the next higher level's Node
South TIEs to find corresponding adjacencies to verify backlink South TIEs to find corresponding adjacencies to verify backlink
connectivity. Two unidirectional links MUST be associated to confirm connectivity. Two unidirectional links MUST be associated to confirm
bidirectional connectivity, a process often known as `backlink bidirectional connectivity, a process often known as "backlink
check`. As part of the check, both Node TIEs MUST contain the correct check". As part of the check, both Node TIEs MUST contain the
System IDs *and* expected levels. correct System IDs *and* expected levels.
The default route found when crossing an E-W link SHOULD be used if The default route found when crossing an E-W link SHOULD be used if
and only if and only if:
1. the node itself does *not* have any northbound adjacencies *and* 1. the node itself does *not* have any northbound adjacencies *and*
2. the adjacent node has one or more northbound adjacencies 2. the adjacent node has one or more northbound adjacencies
This rule forms a "one-hop default route split-horizon" and prevents This rule forms a "one-hop default route split-horizon" and prevents
looping over default routes while allowing for "one-hop protection" looping over default routes while allowing for "one-hop protection"
of nodes that lost all northbound adjacencies except at the ToF where of nodes that lost all northbound adjacencies, except at the ToF
the links are used exclusively to flood topology information in where the links are used exclusively to flood topology information in
multi-plane designs. multi-plane designs.
Other south prefixes found when crossing E-W link MAY be used if and Other south prefixes found when crossing E-W links MAY be used if and
only if only if
1. no north neighbors are advertising same or a supersuming non- 1. no north neighbors are advertising the same or a supersuming non-
default prefix *and* default prefix *and*
2. the node does not originate a non-default supersuming prefix 2. the node does not originate a non-default supersuming prefix
itself. itself.
I.e., the E-W link can be used as a gateway of last resort for a That is, the E-W link can be used as a gateway of last resort for a
specific prefix only. Using south prefixes across E-W link can be specific prefix only. Using south prefixes across an E-W link can be
beneficial e.g., on automatic disaggregation in pathological fabric beneficial, e.g., on automatic disaggregation in pathological fabric
partitioning scenarios. partitioning scenarios.
A detailed example can be found in Appendix B.4. A detailed example can be found in Appendix B.4.
6.4.2. Southbound Reachability SPF 6.4.2. Southbound Reachability SPF
S-SPF MUST use the southbound adjacencies in the Node South TIEs S-SPF MUST use the southbound adjacencies in the Node South TIEs
exclusively, i.e. progresses towards nodes at lower levels. Observe exclusively, i.e., progresses towards nodes at lower levels. Observe
that E-W adjacencies are NEVER used in this computation. This that E-W adjacencies are NEVER used in this computation. This
enforces the requirement that a packet traversing in a southbound enforces the requirement that a packet traversing in a southbound
direction must never change its direction. direction must never change its direction.
S-SPF MUST use northbound adjacencies in node North TIEs to verify S-SPF MUST use northbound adjacencies in node North TIEs to verify
backlink connectivity by checking for presence of the link beside backlink connectivity by checking for the presence of the link beside
correct System ID and level. the correct System ID and level.
6.4.3. East-West Forwarding Within a non-ToF Level 6.4.3. East-West Forwarding Within a Non-ToF Level
Using south prefixes over horizontal links MAY occur if the N-SPF Using south prefixes over horizontal links MAY occur if the N-SPF
includes East-West adjacencies in computation. It can protect includes East-West adjacencies in computation. It can protect
against pathological fabric partitioning cases that leave only paths against pathological fabric partitioning cases that leave only paths
to destinations that would necessitate multiple changes of forwarding to destinations that would necessitate multiple changes of the
direction between north and south. forwarding direction between north and south.
6.4.4. East-West Links Within ToF Level 6.4.4. East-West Links Within a ToF Level
E-W ToF links behave in terms of flooding scopes defined in E-W ToF links behave in terms of flooding scopes defined in
Section 6.3.4 like northbound links and MUST be used exclusively for Section 6.3.4 like northbound links and MUST be used exclusively for
control plane information flooding. Even though a ToF node could be control plane information flooding. Even though a ToF node could be
tempted to use those links during southbound SPF and carry traffic tempted to use those links during southbound SPF and carry traffic
over them this MUST NOT be attempted since it may, in anycast cases, over them, this MUST NOT be attempted since it may, in anycast cases,
lead to routing loops. An implementation MAY try to resolve the lead to routing loops. An implementation MAY try to resolve the
looping problem by following on the ring strictly tie-broken looping problem by following on the ring strictly tie-broken
shortest-paths only but the details are outside this specification. shortest-paths only, but the details are outside this specification.
And even then, the problem of proper capacity provisioning of such And even then, the problem of proper capacity provisioning of such
links when they become traffic-bearing in case of failures is vexing links when they become traffic-bearing in case of failures is vexing,
and when used for forwarding purposes, they defeat statistical non- and when used for forwarding purposes, they defeat statistical non-
blocking guarantees that Clos is providing normally. blocking guarantees that Clos is providing normally.
6.5. Automatic Disaggregation on Link & Node Failures 6.5. Automatic Disaggregation on Link & Node Failures
6.5.1. Positive, Non-transitive Disaggregation 6.5.1. Positive, Non-Transitive Disaggregation
Under normal circumstances, a node's South TIEs contain just the Under normal circumstances, a node's South TIEs contain just the
adjacencies and a default route. However, if a node detects that its adjacencies and a default route. However, if a node detects that its
default IP prefix covers one or more prefixes that are reachable default IP prefix covers one or more prefixes that are reachable
through it but not through one or more other nodes at the same level, through it but not through one or more other nodes at the same level,
then it MUST explicitly advertise those prefixes in a South TIE. then it MUST explicitly advertise those prefixes in a South TIE.
Otherwise, some percentage of the northbound traffic for those Otherwise, some percentage of the northbound traffic for those
prefixes would be sent to nodes without corresponding reachability, prefixes would be sent to nodes without corresponding reachability,
causing it to be dropped. Even when traffic is not being dropped, causing it to be dropped. Even when traffic is not being dropped,
the resulting forwarding could 'backhaul' packets through the higher the resulting forwarding could "backhaul" packets through the higher-
level spines, clearly an undesirable condition affecting the blocking level spines, clearly an undesirable condition affecting the blocking
probabilities of the fabric. probabilities of the fabric.
This specification refers to the process of advertising additional This specification refers to the process of advertising additional
prefixes southbound as 'positive disaggregation'. Such prefixes southbound as "positive disaggregation". Such
disaggregation is non-transitive, i.e., its effects are always disaggregation is non-transitive, i.e., its effects are always
constrained to a single level of the fabric. Naturally, multiple constrained to a single level of the fabric. Naturally, multiple
node or link failures can lead to several independent instances of node or link failures can lead to several independent instances of
positive disaggregation necessary to prevent looping or bow-tying the positive disaggregation necessary to prevent looping or bow-tying the
fabric. fabric.
A node determines the set of prefixes needing disaggregation using A node determines the set of prefixes needing disaggregation using
the following steps: the following steps:
1. A DAG computation in the southern direction is performed first. 1. A DAG computation in the southern direction is performed first.
The North TIEs are used to find all of the prefixes it can reach The North TIEs are used to find all of the prefixes it can reach
and the set of next-hops in the lower level for each of them. and the set of next hops in the lower level for each of them.
Such a computation can be easily performed on a Fat Tree by Such a computation can be easily performed on a Fat Tree by
setting all link costs in the southern direction to 1 and all setting all link costs in the southern direction to 1 and all
northern directions to infinity. We term set of those northern directions to infinity. The set of those prefixes is
prefixes |R, and for each prefix, r, in |R, its set of next-hops referred to as |R; for each prefix r in |R, its set of next hops
is defined to be |H(r). is |H(r).
2. The node uses reflected South TIEs to find all nodes at the same 2. The node uses reflected South TIEs to find all nodes at the same
level in the same PoD and the set of southbound adjacencies for level in the same PoD and the set of southbound adjacencies for
each. The set of nodes at the same level is termed |N and for each. The set of nodes at the same level is termed |N, and for
each node, n, in |N, its set of southbound adjacencies is defined each node, n, in |N, its set of southbound adjacencies is defined
to be |A(n). to be |A(n).
3. For a given r, if the intersection of |H(r) and |A(n), for any n, 3. For a given r, if the intersection of |H(r) and |A(n), for any n,
is empty then that prefix r must be explicitly advertised by the is empty, then that prefix r must be explicitly advertised by the
node in a South TIE. node in a South TIE.
4. Identical set of disaggregated prefixes is flooded on each of the 4. An identical set of disaggregated prefixes is flooded on each of
node's southbound adjacencies. In accordance with the normal the node's southbound adjacencies. In accordance with the normal
flooding rules for a South TIE, a node at the lower level that flooding rules for a South TIE, a node at the lower level that
receives this South TIE SHOULD NOT propagate it south-bound or receives this South TIE SHOULD NOT propagate it southbound or
reflect the disaggregated prefixes back over its adjacencies to reflect the disaggregated prefixes back over its adjacencies to
nodes at the level from which it was received. nodes at the level from which it was received.
To summarize the above in simplest terms: if a node detects that its To summarize the above in simplest terms: If a node detects that its
default route encompasses prefixes for which one of the other nodes default route encompasses prefixes for which one of the other nodes
in its level has no possible next-hops in the level below, it has to in its level has no possible next hops in the level below, it has to
disaggregate it to prevent traffic loss or suboptimal routing through disaggregate it to prevent traffic loss or suboptimal routing through
such nodes. Hence, a node X needs to determine if it can reach a such nodes. Hence, a node X needs to determine if it can reach a
different set of south neighbors than other nodes at the same level, different set of south neighbors than other nodes at the same level,
which are connected to it via at least one common south neighbor. If which are connected to it via at least one common south neighbor. If
it can, then prefix disaggregation may be required. If it can't, it can, then prefix disaggregation may be required. If it can't,
then no prefix disaggregation is needed. An example of then no prefix disaggregation is needed. An example of
disaggregation is provided in Appendix B.3. disaggregation is provided in Appendix B.3.
Finally, a possible algorithm is described here: Finally, a possible algorithm is described here:
1. Create partial_neighbors = (empty), a set of neighbors with 1. Create partial_neighbors = (empty), a set of neighbors with
partial connectivity to the node X's level from X's perspective. partial connectivity to the node X's level from X's perspective.
Each entry in the set is a south neighbor of X and a list of Each entry in the set is a south neighbor of X and a list of
nodes of X.level that can't reach that neighbor. nodes of X.level that can't reach that neighbor.
2. A node X determines its set of southbound neighbors 2. A node X determines its set of southbound neighbors
X.south_neighbors. X.south_neighbors.
3. For each South TIE originated from a node Y that X has which is 3. For each South TIE originated from a node Y that X has, which is
at X.level, if Y.south_neighbors is not the same as at X.level, if Y.south_neighbors is not the same as
X.south_neighbors but the nodes share at least one southern X.south_neighbors but the nodes share at least one southern
neighbor, for each neighbor N in X.south_neighbors but not in neighbor, for each neighbor N in X.south_neighbors but not in
Y.south_neighbors, add (N, (Y)) to partial_neighbors if N isn't Y.south_neighbors, add (N, (Y)) to partial_neighbors if N isn't
there or add Y to the list for N. there or add Y to the list for N.
4. If partial_neighbors is empty, then node X does not disaggregate 4. If partial_neighbors is empty, then node X does not disaggregate
any prefixes. If node X is advertising disaggregated prefixes in any prefixes. If node X is advertising disaggregated prefixes in
its South TIE, X SHOULD remove them and re-advertise its South its South TIE, X SHOULD remove them and re-advertise its South
TIEs. TIEs.
A node X computes reachability to all nodes below it based upon the A node X computes reachability to all nodes below it based upon the
received North TIEs first. This results in a set of routes, each received North TIEs first. This results in a set of routes, each
categorized by (prefix, path_distance, next-hop set). Alternately, categorized by (prefix, path_distance, next-hop set). Alternately,
for clarity in the following procedure, these can be organized by for clarity in the following procedure, these can be organized by a
next-hop set as ((next-hops), {(prefix, path_distance)}). If next-hop set as ((next-hops), {(prefix, path_distance)}). If
partial_neighbors isn't empty, then the procedure in Figure 17 partial_neighbors isn't empty, then the procedure in Figure 17
describes how to identify prefixes to disaggregate. describes how to identify prefixes to disaggregate.
disaggregated_prefixes = { empty } disaggregated_prefixes = { empty }
nodes_same_level = { empty } nodes_same_level = { empty }
for each South TIE for each South TIE
if (South TIE.level == X.level and if (South TIE.level == X.level and
X shares at least one S-neighbor with X) X shares at least one S-neighbor with X)
add South TIE.originator to nodes_same_level add South TIE.originator to nodes_same_level
end if end if
end for end for
for each next-hop-set NHS for each next-hop-set NHS
isolated_nodes = nodes_same_level isolated_nodes = nodes_same_level
for each NH in NHS for each NH in NHS
if NH in partial_neighbors if NH in partial_neighbors
isolated_nodes = isolated_nodes =
intersection(isolated_nodes, intersection(isolated_nodes,
partial_neighbors[NH].nodes) partial_neighbors[NH].nodes)
end if end if
end for end for
if isolated_nodes is not empty if isolated_nodes is not empty
for each prefix using NHS for each prefix using NHS
add (prefix, distance) to disaggregated_prefixes add (prefix, distance) to disaggregated_prefixes
end for end for
end if end if
end for end for
copy disaggregated_prefixes to X's South TIE copy disaggregated_prefixes to X's South TIE
if X's South TIE is different if X's South TIE is different
schedule South TIE for flooding schedule South TIE for flooding
end if end if
Figure 17: Computation of Disaggregated Prefixes Figure 17: Computation of Disaggregated Prefixes
Each disaggregated prefix is sent with the corresponding Each disaggregated prefix is sent with the corresponding
path_distance. This allows a node to send the same South TIE to each path_distance. This allows a node to send the same South TIE to each
south neighbor. The south neighbor which is connected to that prefix south neighbor. The south neighbor that is connected to that prefix
will thus have a shorter path. will thus have a shorter path.
Finally, to summarize the less obvious points partially omitted in Finally, to summarize the less obvious points partially omitted in
the algorithms to keep them more tractable: the algorithms to keep them more tractable:
1. all neighbor relationships MUST perform backlink checks. 1. All neighbor relationships MUST perform backlink checks.
2. overload flag as introduced in Section 6.8.2 and carried in the 2. The overload flag as introduced in Section 6.8.2 and carried in
_overload_ schema element have to be respected during the the _overload_ schema element has to be respected during the
computation. Nodes advertising themselves as overloaded MUST NOT computation. Nodes advertising themselves as overloaded MUST NOT
be transited in reachability computation but MUST be used as be transited in reachability computation but MUST be used as
terminal nodes with prefixes they advertise being reachable. terminal nodes with prefixes they advertise being reachable.
3. all the lower-level nodes are flooded the same disaggregated 3. All the lower-level nodes are flooded to the same disaggregated
prefixes since RIFT does not build a South TIE per node which prefixes since RIFT does not build a South TIE per node, which
would complicate things unnecessarily. The lower-level node that would complicate things unnecessarily. The lower-level node that
can compute a southbound route to the prefix will prefer it to can compute a southbound route to the prefix will prefer it to
the disaggregated route anyway based on route preference rules. the disaggregated route anyway based on route preference rules.
4. positively disaggregated prefixes do *not* have to propagate to 4. Positively disaggregated prefixes do *not* have to propagate to
lower levels. With that the disturbance in terms of new flooding lower levels. With that, the disturbance in terms of new
is contained to a single level experiencing failures. flooding is contained to a single level experiencing failures.
5. disaggregated Prefix South TIEs are not "reflected" by the lower 5. Disaggregated Prefix South TIEs are not "reflected" by the lower
level. Nodes within same level do *not* need to be aware which level. Nodes within the same level do *not* need to be aware of
node computed the need for disaggregation. which node computed the need for disaggregation.
6. The fabric is still supporting maximum load balancing properties 6. The fabric is still supporting maximum load balancing properties
while not trying to send traffic northbound unless necessary. while not trying to send traffic northbound unless necessary.
In case positive disaggregation is triggered and due to the very In case positive disaggregation is triggered and due to the very
stable but un-synchronized nature of the algorithm the nodes may stable but unsynchronized nature of the algorithm, the nodes may
issue the necessary disaggregated prefixes at different points in issue the necessary disaggregated prefixes at different points in
time. This can lead for a short time to an "incast" behavior where time. For a short time, this can lead to an "incast" behavior where
the first advertising router based on the nature of longest prefix the first advertising router based on the nature of the longest
match will attract all the traffic. Different implementation prefix match will attract all the traffic. Different implementation
strategies can be used to lessen that effect, but those are outside strategies can be used to lessen that effect, but those are outside
the scope of this specification. the scope of this specification.
It is worth observing that, in a single plane ToF, this It is worth observing that, in a single plane ToF, this
disaggregation prevents traffic loss up to (K_LEAF * P) link failures disaggregation prevents traffic loss up to (K_LEAF * P) link failures
in terms of Section 5.2 or, in other terms, it takes at minimum that in terms of Section 5.2 or, in other terms, it takes at minimum that
many link failures to partition the ToF into multiple planes. many link failures to partition the ToF into multiple planes.
6.5.2. Negative, Transitive Disaggregation for Fallen Leaves 6.5.2. Negative, Transitive Disaggregation for Fallen Leaves
As explained in Section 5.3 failures in multi-plane ToF or more than As explained in Section 5.3, failures in multi-plane ToF or more than
(K_LEAF * P) links failing in single plane design can generate fallen (K_LEAF * P) links failing in single plane design can generate fallen
leaves. Such scenario cannot be addressed by positive disaggregation leaves. Such scenario cannot be addressed by positive disaggregation
only and needs a further mechanism. only and needs a further mechanism.
6.5.2.1. Cabling of Multiple ToF Planes 6.5.2.1. Cabling of Multiple ToF Planes
Returning in this section to designs with multiple planes as shown Returning in this section to designs with multiple planes as shown
originally in Figure 3, Figure 18 highlights how the ToF is cabled in originally in Figure 3, Figure 18 highlights how the ToF is cabled in
case of two planes by the means of dual-rings to distribute all the case of two planes by the means of dual-rings to distribute all the
North TIEs within both planes. North TIEs within both planes.
skipping to change at page 85, line 25 skipping to change at line 3806
| +-+ 1 +---||--------+ 1 +--||---------+ 1 +--||---------+ 1 +-+ || | | +-+ 1 +---||--------+ 1 +--||---------+ 1 +--||---------+ 1 +-+ || |
| +--++ || . +-+++ || . +-+++ || . +-+++ || | | +--++ || . +-+++ || . +-+++ || . +-+++ || |
| || || . || || . || || . || || | | || || . || || . || || . || || |
| || || . || || . || || . || || | | || || . || || . || || . || || |
Figure 18: Topologically Connected Planes Figure 18: Topologically Connected Planes
Section 5.3 already describes how failures in multi-plane fabrics can Section 5.3 already describes how failures in multi-plane fabrics can
lead to traffic loss that normal positive disaggregation cannot fix. lead to traffic loss that normal positive disaggregation cannot fix.
The mechanism of negative, transitive disaggregation incorporated in The mechanism of negative, transitive disaggregation incorporated in
RIFT provides the corresponding solution and next section explains RIFT provides the corresponding solution, and the next section
the involved mechanisms in more detail. explains the involved mechanisms in more detail.
6.5.2.2. Transitive Advertisement of Negative Disaggregates 6.5.2.2. Transitive Advertisement of Negative Disaggregates
A ToF node discovering that it cannot reach a fallen leaf SHOULD A ToF node discovering that it cannot reach a fallen leaf SHOULD
disaggregate all the prefixes of that leaf. It uses for that purpose disaggregate all the prefixes of that leaf. For that purpose, it
negative prefix South TIEs that are, as usual, flooded southwards uses negative prefix South TIEs that are, as usual, flooded
with the scope defined in Section 6.3.4. southwards with the scope defined in Section 6.3.4.
Transitively, a node explicitly loses connectivity to a prefix when Transitively, a node explicitly loses connectivity to a prefix when
none of its children advertises it and when the prefix is negatively none of its children advertises it and when the prefix is negatively
disaggregated by all of its parents. When that happens, the node disaggregated by all of its parents. When that happens, the node
originates the negative prefix further down south. Since the originates the negative prefix further down south. Since the
mechanism applies recursively south the negative prefix may propagate mechanism applies recursively south, the negative prefix may
transitively all the way down to the leaf. This is necessary since propagate transitively all the way down to the leaf. This is
leaves connected to multiple planes by means of disjointed paths may necessary since leaves connected to multiple planes by means of
have to choose the correct plane at the very bottom of the fabric to disjointed paths may have to choose the correct plane at the very
make sure that they don't send traffic towards another leaf using a bottom of the fabric to make sure that they don't send traffic
plane where it is "fallen" which would make traffic loss unavoidable. towards another leaf using a plane where it is "fallen", which would
make traffic loss unavoidable.
When connectivity is restored, a node that disaggregated a prefix When connectivity is restored, a node that disaggregated a prefix
withdraws the negative disaggregation by the usual mechanism of re- withdraws the negative disaggregation by the usual mechanism of re-
advertising TIEs omitting the negative prefix. advertising TIEs omitting the negative prefix.
6.5.2.3. Computation of Negative Disaggregates 6.5.2.3. Computation of Negative Disaggregates
Negative prefixes can in fact be advertised due to two different Negative prefixes can in fact be advertised due to two different
triggers. This will be described consecutively. triggers. This will be described consecutively.
The first origination reason is a computation that uses all the node The first origination reason is a computation that uses all the node
North TIEs to build the set of all reachable nodes by reachability North TIEs to build the set of all reachable nodes by reachability
computation over the complete graph and including horizontal ToF computation over the complete graph, including horizontal ToF links.
links. The computation uses the node itself as root. This is The computation uses the node itself as the root. This is compared
compared with the result of the normal southbound SPF as described in with the result of the normal southbound SPF as described in
Section 6.4.2. The difference are the fallen leaves and all their Section 6.4.2. The differences are the fallen leaves and all their
attached prefixes are advertised as negative prefixes southbound if attached prefixes are advertised as negative prefixes southbound if
the node does not consider the prefix to be reachable within the the node does not consider the prefix to be reachable within the
southbound SPF. southbound SPF.
The second origination reason hinges on the understanding how the The second origination reason hinges on the understanding of how the
negative prefixes are used within the computation as described in negative prefixes are used within the computation as described in
Figure 19. When attaching the negative prefixes at a certain point Figure 19. When attaching the negative prefixes at a certain point
in time the negative prefix may find itself with all the viable nodes in time, the negative prefix may find itself with all the viable
from the shorter match nexthop being pruned. In other words, all its nodes from the shorter match next hop being pruned. In other words,
northbound neighbors provided a negative prefix advertisement. This all its northbound neighbors provided a negative prefix
is the trigger to advertise this negative prefix transitively south advertisement. This is the trigger to advertise this negative prefix
and is normally caused by the node being in a plane where the prefix transitively south and is normally caused by the node being in a
belongs to a fabric leaf that has "fallen" in this plane. Obviously, plane where the prefix belongs to a fabric leaf that has "fallen" in
when one of the northbound switches withdraws its negative this plane. Obviously, when one of the northbound switches withdraws
advertisement, the node has to withdraw its transitively provided its negative advertisement, the node has to withdraw its transitively
negative prefix as well. provided negative prefix as well.
6.6. Attaching Prefixes 6.6. Attaching Prefixes
After an SPF is run, it is necessary to attach the resulting After an SPF is run, it is necessary to attach the resulting
reachability information in form of prefixes. For S-SPF, prefixes reachability information in the form of prefixes. For S-SPF,
from a North TIE are attached to the originating node with that prefixes from a North TIE are attached to the originating node with
node's next-hop set and a distance equal to the prefix's cost plus that node's next-hop set and a distance equal to the prefix's cost
the node's minimized path distance. The RIFT route database, a set plus the node's minimized path distance. The RIFT route database, a
of (prefix, prefix-type, attributes, path_distance, next-hop set), set of (prefix, prefix-type, attributes, path_distance, next-hop
accumulates these results. set), accumulates these results.
N-SPF prefixes from each South TIE need to also be added to the RIFT N-SPF prefixes from each South TIE need to also be added to the RIFT
route database. The N-SPF is really just a stub so the computing route database. The N-SPF is really just a stub so the computing
node needs simply to determine, for each prefix in a South TIE that node simply needs to determine, for each prefix in a South TIE that
originated from adjacent node, what next-hops to use to reach that originated from adjacent node, what next hops to use to reach that
node. Since there may be parallel links, the next-hops to use can be node. Since there may be parallel links, the next hops to use can be
a set; presence of the computing node in the associated Node South a set; the presence of the computing node in the associated Node
TIE is sufficient to verify that at least one link has bidirectional South TIE is sufficient to verify that at least one link has
connectivity. The set of minimum cost next-hops from the computing bidirectional connectivity. The set of minimum cost next hops from
node X to the originating adjacent node is determined. the computing node X to the originating adjacent node is determined.
Each prefix has its cost adjusted before being added into the RIFT Each prefix has its cost adjusted before being added into the RIFT
route database. The cost of the prefix is set to the cost received route database. The cost of the prefix is set to the cost received
plus the cost of the minimum distance next-hop to that neighbor while plus the cost of the minimum distance next hop to that neighbor while
considering its attributes such as mobility per Section 6.8.4. Then considering its attributes such as mobility per Section 6.8.4. Then
each prefix can be added into the RIFT route database with the next- each prefix can be added into the RIFT route database with the next-
hop set; ties are broken based upon type first and then distance and hop set; ties are broken based upon type first and then distance and
further on _PrefixAttributes_. Only the best combination is used for further on _PrefixAttributes_. Only the best combination is used for
forwarding. RIFT route preferences are normalized by the enum forwarding. RIFT route preferences are normalized by the enum
_RouteType_ in Thrift [thrift] model given in Section 7. _RouteType_ in the Thrift [thrift] model given in Section 7.
An example implementation for node X follows: An example implementation for node X follows:
for each South TIE for each South TIE
if South TIE.level > X.level if South TIE.level > X.level
next_hop_set = set of minimum cost links to the next_hop_set = set of minimum cost links to the
South TIE.originator South TIE.originator
next_hop_cost = minimum cost link to next_hop_cost = minimum cost link to
South TIE.originator South TIE.originator
end if end if
for each prefix P in the South TIE for each prefix P in the South TIE
P.cost = P.cost + next_hop_cost P.cost = P.cost + next_hop_cost
if P not in route_database: if P not in route_database:
add (P, P.cost, P.type, add (P, P.cost, P.type,
P.attributes, next_hop_set) to route_database P.attributes, next_hop_set) to route_database
end if end if
if (P in route_database): if (P in route_database):
if route_database[P].cost > P.cost or if route_database[P].cost > P.cost or
route_database[P].type > P.type: route_database[P].type > P.type:
update route_database[P] with (P, P.type, P.cost, update route_database[P] with (P, P.type, P.cost,
P.attributes, P.attributes,
next_hop_set) next_hop_set)
else if route_database[P].cost == P.cost and else if route_database[P].cost == P.cost and
route_database[P].type == P.type: route_database[P].type == P.type:
update route_database[P] with (P, P.type, update route_database[P] with (P, P.type,
P.cost, P.attributes, P.cost, P.attributes,
merge(next_hop_set, route_database[P].next_hop_set)) merge(next_hop_set, route_database[P].next_hop_set))
else else
// Not preferred route so ignore // Not preferred route so ignore
end if end if
end if end if
end for end for
end for end for
Figure 19: Adding Routes from South TIE Positive and Negative Figure 19: Adding Routes from South TIE Positive and Negative
Prefixes Prefixes
After the positive prefixes are attached and tie-broken, negative After the positive prefixes are attached and tie-broken, negative
prefixes are attached and used in case of northbound computation, prefixes are attached and used in case of northbound computation,
ideally from the shortest length to the longest. The nexthop ideally from the shortest length to the longest. The next-hop
adjacencies for a negative prefix are inherited from the longest adjacencies for a negative prefix are inherited from the longest
positive prefix that aggregates it, and subsequently adjacencies to positive prefix that aggregates it, and subsequently adjacencies to
nodes that advertised negative for this prefix are removed. nodes that advertised negative for this prefix are removed.
The rule of inheritance MUST be maintained when the nexthop list for The rule of inheritance MUST be maintained when the next-hop list for
a prefix is modified, as the modification may affect the entries for a prefix is modified, as the modification may affect the entries for
matching negative prefixes of immediate longer prefix length. For matching negative prefixes of immediate longer prefix length. For
instance, if a nexthop is added, then by inheritance it must be added instance, if a next hop is added, then by inheritance, it must be
to all the negative routes of immediate longer prefixes length unless added to all the negative routes of immediate longer prefixes length
it is pruned due to a negative advertisement for the same next hop. unless it is pruned due to a negative advertisement for the same next
Similarly, if a nexthop is deleted for a given prefix, then it is hop. Similarly, if a next hop is deleted for a given prefix, then it
deleted for all the immediately aggregated negative routes. This is deleted for all the immediately aggregated negative routes. This
will recurse in the case of nested negative prefix aggregations. will recurse in the case of nested negative prefix aggregations.
The rule of inheritance MUST also be maintained when a new prefix of The rule of inheritance MUST also be maintained when a new prefix of
intermediate length is inserted, or when the immediately aggregating intermediate length is inserted or when the immediately aggregating
prefix is deleted from the routing table, making an even shorter prefix is deleted from the routing table, making an even shorter
aggregating prefix the one from which the negative routes now inherit aggregating prefix the one from which the negative routes now inherit
their adjacencies. As the aggregating prefix changes, all the their adjacencies. As the aggregating prefix changes, all the
negative routes MUST be recomputed, and then again the process may negative routes MUST be recomputed, and then again, the process may
recurse in case of nested negative prefix aggregations. recurse in case of nested negative prefix aggregations.
Although these operations can be computationally expensive, the Although these operations can be computationally expensive, the
overall load on devices in the network is low because these overall load on devices in the network is low because these
computations are not run very often, as positive route advertisements computations are not run very often, as positive route advertisements
are always preferred over negative ones. This prevents recursion in are always preferred over negative ones. This prevents recursion in
most cases because positive reachability information never inherits most cases because positive reachability information never inherits
next hops. next hops.
To make the negative disaggregation less abstract and provide an To make the negative disaggregation less abstract and provide an
example ToP node T1 with 4 ToF parents S1..S4 as represented in example ToP node, T1 with 4 ToF parents S1..S4 as represented in
Figure 20 are considered further: Figure 20 are considered further:
+----+ +----+ +----+ +----+ N +----+ +----+ +----+ +----+ N
| S1 | | S2 | | S3 | | S4 | ^ | S1 | | S2 | | S3 | | S4 | ^
+----+ +----+ +----+ +----+ W< + >E +----+ +----+ +----+ +----+ W< + >E
| | | | v | | | | v
|+--------+ | | S |+--------+ | | S
||+-----------------+ | ||+-----------------+ |
|||+----------------+---------+ |||+----------------+---------+
|||| ||||
skipping to change at page 89, line 4 skipping to change at line 3973
| S1 | | S2 | | S3 | | S4 | ^ | S1 | | S2 | | S3 | | S4 | ^
+----+ +----+ +----+ +----+ W< + >E +----+ +----+ +----+ +----+ W< + >E
| | | | v | | | | v
|+--------+ | | S |+--------+ | | S
||+-----------------+ | ||+-----------------+ |
|||+----------------+---------+ |||+----------------+---------+
|||| ||||
+----+ +----+
| T1 | | T1 |
+----+ +----+
Figure 20: A ToP Node with 4 Parents Figure 20: A ToP Node with 4 Parents
If all ToF nodes can reach all the prefixes in the network; with If all ToF nodes can reach all the prefixes in the network, with
RIFT, they will normally advertise a default route south. An RIFT, they will normally advertise a default route south. An
abstract Routing Information Base (RIB), more commonly known as a abstract Routing Information Base (RIB), more commonly known as a
routing table, stores all types of maintained routes including the routing table, stores all types of maintained routes, including the
negative ones and "tie-breaks" for the best one, whereas an abstract negative ones and "tie-breaks" for the best one, whereas an abstract
Forwarding table (FIB) retains only the ultimately computed forwarding table (FIB) retains only the ultimately computed
"positive" routing instructions. In T1, those tables would look as "positive" routing instructions. In T1, those tables would look as
illustrated in Figure 21: illustrated in Figure 21:
+---------+ +---------+
| Default | | Default |
+---------+ +---------+
| |
| +--------+ | +--------+
+---> | Via S1 | +---> | Via S1 |
| +--------+ | +--------+
skipping to change at page 89, line 38 skipping to change at line 4008
+---> | Via S3 | +---> | Via S3 |
| +--------+ | +--------+
| |
| +--------+ | +--------+
+---> | Via S4 | +---> | Via S4 |
+--------+ +--------+
Figure 21: Abstract RIB Figure 21: Abstract RIB
In case T1 receives a negative advertisement for prefix 2001:db8::/32 In case T1 receives a negative advertisement for prefix 2001:db8::/32
from S1 a negative route is stored in the RIB (indicated by a ~ from S1, a negative route is stored in the RIB (indicated by a "~"
sign), while the more specific routes to the complementing ToF nodes sign), while the more specific routes to the complementing ToF nodes
are installed in FIB. RIB and FIB in T1 now look as illustrated in are installed in FIB. RIB and FIB in T1 now look as illustrated in
Figure 22 and Figure 23, respectively: Figures 22 and 23, respectively:
+---------+ +-----------------+ +---------+ +-----------------+
| Default | <-------------- | ~2001:db8::/32 | | Default | <-------------- | ~2001:db8::/32 |
+---------+ +-----------------+ +---------+ +-----------------+
| | | |
| +--------+ | +--------+ | +--------+ | +--------+
+---> | Via S1 | +---> | Via S1 | +---> | Via S1 | +---> | Via S1 |
| +--------+ +--------+ | +--------+ +--------+
| |
| +--------+ | +--------+
skipping to change at page 90, line 25 skipping to change at line 4033
| +--------+ | +--------+
| |
| +--------+ | +--------+
+---> | Via S3 | +---> | Via S3 |
| +--------+ | +--------+
| |
| +--------+ | +--------+
+---> | Via S4 | +---> | Via S4 |
+--------+ +--------+
Figure 22: Abstract RIB after Negative 2001:db8::/32 from S1 Figure 22: Abstract RIB After Negative 2001:db8::/32 from S1
The negative 2001:db8::/32 prefix entry inherits from ::/0, so the The negative 2001:db8::/32 prefix entry inherits from ::/0, so the
positive more specific routes are the complements to S1 in the set of positive, more specific routes are the complements to S1 in the set
next-hops for the default route. That entry is composed of S2, S3, of next hops for the default route. That entry is composed of S2,
and S4, or, in other words, it uses all entries in the default route S3, and S4, or in other words, it uses all entries in the default
with a "hole punched" for S1 into them. These are the next hops that route with a "hole punched" for S1 into them. These are the next
are still available to reach 2001:db8::/32, now that S1 advertised hops that are still available to reach 2001:db8::/32 now that S1
that it will not forward 2001:db8::/32 anymore. Ultimately, those advertised that it will not forward 2001:db8::/32 anymore.
resulting next-hops are installed in FIB for the more specific route Ultimately, those resulting next hops are installed in FIB for the
to 2001:db8::/32 as illustrated below: more specific route to 2001:db8::/32 as illustrated below:
+---------+ +---------------+ +---------+ +---------------+
| Default | | 2001:db8::/32 | | Default | | 2001:db8::/32 |
+---------+ +---------------+ +---------+ +---------------+
| | | |
| +--------+ | | +--------+ |
+---> | Via S1 | | +---> | Via S1 | |
| +--------+ | | +--------+ |
| | | |
| +--------+ | +--------+ | +--------+ | +--------+
skipping to change at page 91, line 25 skipping to change at line 4065
| +--------+ | +--------+ | +--------+ | +--------+
| | | |
| +--------+ | +--------+ | +--------+ | +--------+
+---> | Via S3 | +---> | Via S3 | +---> | Via S3 | +---> | Via S3 |
| +--------+ | +--------+ | +--------+ | +--------+
| | | |
| +--------+ | +--------+ | +--------+ | +--------+
+---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 |
+--------+ +--------+ +--------+ +--------+
Figure 23: Abstract FIB after Negative 2001:db8::/32 from S1 Figure 23: Abstract FIB After Negative 2001:db8::/32 from S1
To illustrate matters further consider T1 receiving a negative To illustrate matters further, consider T1 receiving a negative
advertisement for prefix 2001:db8:1::/48 from S2, which is stored in advertisement for prefix 2001:db8:1::/48 from S2, which is stored in
RIB again. After the update, the RIB in T1 is illustrated in RIB again. After the update, the RIB in T1 is illustrated in
Figure 24: Figure 24:
+---------+ +----------------+ +------------------+ +---------+ +----------------+ +------------------+
| Default | <----- | ~2001:db8::/32 | <------ | ~2001:db8:1::/48 | | Default | <----- | ~2001:db8::/32 | <------ | ~2001:db8:1::/48 |
+---------+ +----------------+ +------------------+ +---------+ +----------------+ +------------------+
| | | | | |
| +--------+ | +--------+ | | +--------+ | +--------+ |
+---> | Via S1 | +---> | Via S1 | | +---> | Via S1 | +---> | Via S1 | |
skipping to change at page 91, line 52 skipping to change at line 4092
| +--------+ +--------+ | +--------+ +--------+
| |
| +--------+ | +--------+
+---> | Via S3 | +---> | Via S3 |
| +--------+ | +--------+
| |
| +--------+ | +--------+
+---> | Via S4 | +---> | Via S4 |
+--------+ +--------+
Figure 24: Abstract RIB after Negative 2001:db8:1::/48 from S2 Figure 24: Abstract RIB After Negative 2001:db8:1::/48 from S2
Negative 2001:db8:1::/48 inherits from 2001:db8::/32 now, so the Negative 2001:db8:1::/48 inherits from 2001:db8::/32 now, so the
positive more specific routes are the complements to S2 in the set of positive, more specific routes are the complements to S2 in the set
next hops for 2001:db8::/32, which are S3 and S4, or, in other words, of next hops for 2001:db8::/32, which are S3 and S4, or in other
all entries of the parent with the negative holes "punched in" again. words, all entries of the parent with the negative holes "punched in"
After the update, the FIB in T1 shows as illustrated in Figure 25: again. After the update, the FIB in T1 shows as illustrated in
Figure 25:
+---------+ +---------------+ +-----------------+ +---------+ +---------------+ +-----------------+
| Default | | 2001:db8::/32 | | 2001:db8:1::/48 | | Default | | 2001:db8::/32 | | 2001:db8:1::/48 |
+---------+ +---------------+ +-----------------+ +---------+ +---------------+ +-----------------+
| | | | | |
| +--------+ | | | +--------+ | |
+---> | Via S1 | | | +---> | Via S1 | | |
| +--------+ | | | +--------+ | |
| | | | | |
| +--------+ | +--------+ | | +--------+ | +--------+ |
skipping to change at page 92, line 31 skipping to change at line 4121
| +--------+ | +--------+ | | +--------+ | +--------+ |
| | | | | |
| +--------+ | +--------+ | +--------+ | +--------+ | +--------+ | +--------+
+---> | Via S3 | +---> | Via S3 | +---> | Via S3 | +---> | Via S3 | +---> | Via S3 | +---> | Via S3 |
| +--------+ | +--------+ | +--------+ | +--------+ | +--------+ | +--------+
| | | | | |
| +--------+ | +--------+ | +--------+ | +--------+ | +--------+ | +--------+
+---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
Figure 25: Abstract FIB after Negative 2001:db8:1::/48 from S2 Figure 25: Abstract FIB After Negative 2001:db8:1::/48 from S2
Further, assume that S3 stops advertising its service as default Further, assume that S3 stops advertising its service as a default
gateway. The entry is removed from RIB as usual. In order to update gateway. The entry is removed from RIB as usual. In order to update
the FIB, it is necessary to eliminate the FIB entry for the default the FIB, it is necessary to eliminate the FIB entry for the default
route, as well as all the FIB entries that were created for negative route, as well as all the FIB entries that were created for negative
routes pointing to the RIB entry being removed (::/0). This is done routes pointing to the RIB entry being removed (::/0). This is done
recursively for 2001:db8::/32 and then for, 2001:db8:1::/48. The recursively for 2001:db8::/32 and then for 2001:db8:1::/48. The
related FIB entries via S3 are removed, as illustrated in Figure 26. related FIB entries via S3 are removed as illustrated in Figure 26.
+---------+ +---------------+ +-----------------+ +---------+ +---------------+ +-----------------+
| Default | | 2001:db8::/32 | | 2001:db8:1::/48 | | Default | | 2001:db8::/32 | | 2001:db8:1::/48 |
+---------+ +---------------+ +-----------------+ +---------+ +---------------+ +-----------------+
| | | | | |
| +--------+ | | | +--------+ | |
+---> | Via S1 | | | +---> | Via S1 | | |
| +--------+ | | | +--------+ | |
| | | | | |
| +--------+ | +--------+ | | +--------+ | +--------+ |
skipping to change at page 93, line 25 skipping to change at line 4151
| +--------+ | +--------+ | | +--------+ | +--------+ |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| +--------+ | +--------+ | +--------+ | +--------+ | +--------+ | +--------+
+---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
Figure 26: Abstract FIB after Loss of S3 Figure 26: Abstract FIB After Loss of S3
Say that at that time, S4 would also disaggregate prefix Say that at that time, S4 would also disaggregate prefix
2001:db8:1::/48. This would mean that the FIB entry for 2001:db8:1::/48. This would mean that the FIB entry for
2001:db8:1::/48 becomes a discard route, and that would be the signal 2001:db8:1::/48 becomes a discard route, and that would be the signal
for T1 to disaggregate prefix 2001:db8:1::/48 negatively in a for T1 to disaggregate prefix 2001:db8:1::/48 negatively in a
transitive fashion with its own children. transitive fashion with its own children.
Finally, the case occurs where S3 becomes available again as a Finally, the case occurs where S3 becomes available again as a
default gateway, and a negative advertisement is received from S4 default gateway, and a negative advertisement is received from S4
about prefix 2001:db8:2::/48 as opposed to 2001:db8:1::/48. Again, a about prefix 2001:db8:2::/48 as opposed to 2001:db8:1::/48. Again, a
negative route is stored in the RIB, and the more specific route to negative route is stored in the RIB, and the more specific route to
the complementing ToF nodes are installed in FIB. Since the complementing ToF nodes is installed in FIB. Since
2001:db8:2::/48 inherits from 2001:db8::/32, the positive FIB routes 2001:db8:2::/48 inherits from 2001:db8::/32, the positive FIB routes
are chosen by removing S4 from S2, S3, S4. The abstract FIB in T1 are chosen by removing S4 from S2, S3, S4. The abstract FIB in T1
now shows as illustrated in Figure 27: now shows as illustrated in Figure 27:
+-----------------+ +-----------------+
| 2001:db8:2::/48 | | 2001:db8:2::/48 |
+-----------------+ +-----------------+
| |
+---------+ +---------------+ +-----------------+ +---------+ +---------------+ +-----------------+
| Default | | 2001:db8::/32 | | 2001:db8:1::/48 | | Default | | 2001:db8::/32 | | 2001:db8:1::/48 |
skipping to change at page 94, line 29 skipping to change at line 4192
| +--------+ | +--------+ | +--------+ | +--------+ | +--------+ | +--------+
| | | | | |
| +--------+ | +--------+ | +--------+ | +--------+ | +--------+ | +--------+
+---> | Via S3 | +---> | Via S3 | +---> | Via S3 | +---> | Via S3 | +---> | Via S3 | +---> | Via S3 |
| +--------+ | +--------+ | +--------+ | +--------+ | +--------+ | +--------+
| | | | | |
| +--------+ | +--------+ | +--------+ | +--------+ | +--------+ | +--------+
+---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 | +---> | Via S4 |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
Figure 27: Abstract FIB after Negative 2001:db8:2::/48 from S4 Figure 27: Abstract FIB After Negative 2001:db8:2::/48 from S4
6.7. Optional Zero Touch Provisioning (RIFT ZTP) 6.7. Optional Zero Touch Provisioning (RIFT ZTP)
Each RIFT node can operate in zero touch provisioning (ZTP) mode, Each RIFT node can operate in Zero Touch Provisioning (ZTP) mode,
i.e. it has no RIFT specific configuration (unless it is a ToF or it i.e., it has no RIFT-specific configuration (unless it is a ToF or it
is explicitly configured to operate in the overall topology as leaf is explicitly configured to operate in the overall topology as a leaf
and/or support leaf-2-leaf procedures) and it will fully and/or support leaf-to-leaf procedures), and it will fully,
automatically derive necessary RIFT parameters itself after being automatically derive necessary RIFT parameters itself after being
attached to the topology. Manually configured nodes and nodes attached to the topology. Manually configured nodes and nodes
operating using RIFT ZTP can be mixed freely and will form a valid operating using RIFT ZTP can be mixed freely and will form a valid
topology if achievable. topology if achievable.
The derivation of the level of each node happens based on offers The derivation of the level of each node happens based on offers
received from its neighbors whereas each node (with the possible received from its neighbors, whereas each node (with the possible
exception of nodes configured as leaves) tries to attach at the exception of nodes configured as leaves) tries to attach at the
highest possible point in the fabric. This guarantees that even if highest possible point in the fabric. This guarantees that even if
the diffusion front of offers reaches a node from "below" faster than the diffusion front of offers reaches a node from "below" faster than
from "above", it will greedily abandon already negotiated level from "above", it will greedily abandon an already negotiated level
derived from nodes topologically below it and properly peer with derived from nodes topologically below it and properly peer with
nodes above. nodes above.
The fabric is very consciously numbered from the top down to allow The fabric is very consciously numbered from the top down to allow
for PoDs of different heights and to minimize the number of for PoDs of different heights and to minimize the number of
configuration necessary, in this case just a TOP_OF_FABRIC flag on configurations necessary, in this case, just a TOP_OF_FABRIC flag on
every node at the top of the fabric. every node at the top of the fabric.
This section describes the necessary concepts and procedures of RIFT This section describes the necessary concepts and procedures of the
ZTP operation. RIFT ZTP operation.
6.7.1. Terminology 6.7.1. Terminology
The interdependencies between the different flags and the configured The interdependencies between the different flags and the configured
level can be somewhat vexing at first and it may take multiple reads level can be somewhat vexing at first, and it may take multiple reads
of the glossary to comprehend them. of the glossary to comprehend them.
Automatic Level Derivation: Automatic Level Derivation:
Procedures which allow nodes without level configured to derive it Procedures that allow nodes without a level configured to derive
automatically. Only applied if CONFIGURED_LEVEL is undefined. it automatically. Only applied if CONFIGURED_LEVEL is undefined.
UNDEFINED_LEVEL: UNDEFINED_LEVEL:
A "null" value that indicates that the level has not been A "null" value that indicates that the level has not been
determined and has not been configured. Schemas normally indicate determined and has not been configured. Schemas normally indicate
that by a missing optional value without an available defined that by a missing optional value without an available defined
default. default.
LEAF_ONLY: LEAF_ONLY:
An optional configuration flag that can be configured on a node to An optional configuration flag that can be configured on a node to
make sure it never leaves the "bottom of the hierarchy". make sure it never leaves the "bottom of the hierarchy". The
TOP_OF_FABRIC flag and CONFIGURED_LEVEL cannot be defined at the TOP_OF_FABRIC flag and CONFIGURED_LEVEL cannot be defined at the
same time as this flag. It implies CONFIGURED_LEVEL value of same time as this flag. It implies a CONFIGURED_LEVEL value of
_leaf_level_. It is indicated in the _leaf_only_ schema element. _leaf_level_. It is indicated in the _leaf_only_ schema element.
TOP_OF_FABRIC: TOP_OF_FABRIC:
A configuration flag that MUST be provided on all ToF nodes. A configuration flag that MUST be provided on all ToF nodes.
LEAF_FLAG and CONFIGURED_LEVEL cannot be defined at the same time LEAF_FLAG and CONFIGURED_LEVEL cannot be defined at the same time
as this flag. It implies a CONFIGURED_LEVEL value. In fact, it as this flag. It implies a CONFIGURED_LEVEL value. In fact, it
is basically a shortcut for configuring same level at all ToF is basically a shortcut for configuring the same level at all ToF
nodes which is unavoidable since an initial 'seed' is needed for nodes, which is unavoidable since an initial "seed" is needed for
other ZTP nodes to derive their level in the topology. The flag other ZTP nodes to derive their level in the topology. The flag
plays an important role in fabrics with multiple planes to enable plays an important role in fabrics with multiple planes to enable
successful negative disaggregation (Section 6.5.2). It is carried successful negative disaggregation (Section 6.5.2). It is carried
in the _top_of_fabric_ schema element. A standards conforming in the _top_of_fabric_ schema element. A standards-conforming
RIFT implementation implies a CONFIGURED_LEVEL value of RIFT implementation implies a CONFIGURED_LEVEL value of
_top_of_fabric_level_ in case of TOP_OF_FABRIC. This value is _top_of_fabric_level_ in case of TOP_OF_FABRIC. This value is
kept reasonably low to allow for fast ZTP re-convergence on kept reasonably low to allow for fast ZTP reconvergence on
failures. failures.
CONFIGURED_LEVEL: CONFIGURED_LEVEL:
A level value provided manually. When this is defined (i.e. it is A level value provided manually. When this is defined (i.e., it
not an UNDEFINED_LEVEL) the node is not participating in ZTP in is not an UNDEFINED_LEVEL), the node is not participating in ZTP
the sense of deriving its own level based on other nodes' in the sense of deriving its own level based on other nodes'
information. TOP_OF_FABRIC flag is ignored when this value is information. The TOP_OF_FABRIC flag is ignored when this value is
defined. LEAF_ONLY can be set only if this value is undefined or defined. LEAF_ONLY can be set only if this value is undefined or
set to _leaf_level_. set to _leaf_level_.
DERIVED_LEVEL: DERIVED_LEVEL:
Level value computed via automatic level derivation when Level value computed via automatic level derivation when
CONFIGURED_LEVEL is equal to UNDEFINED_LEVEL. CONFIGURED_LEVEL is equal to UNDEFINED_LEVEL.
LEAF_2_LEAF: LEAF_2_LEAF:
An optional flag that can be configured on a node to make sure it An optional flag that can be configured on a node to make sure it
supports procedures defined in Section 6.8.9. It is a capability supports procedures defined in Section 6.8.9. It is a capability
that implies LEAF_ONLY and the corresponding restrictions. that implies LEAF_ONLY and the corresponding restrictions. The
TOP_OF_FABRIC flag is ignored when set at the same time as this TOP_OF_FABRIC flag is ignored when set at the same time as this
flag. It is carried in the _leaf_only_and_leaf_2_leaf_procedures_ flag. It is carried in the _leaf_only_and_leaf_2_leaf_procedures_
schema flag. schema flag.
LEVEL_VALUE: LEVEL_VALUE:
With ZTP, the original definition of "level" in Section 3.1 is With ZTP, the original definition of "level" in Section 3.1 is
both extended and relaxed. First, level is defined now as both extended and relaxed. First, the level is defined now as
LEVEL_VALUE and is the first defined value of CONFIGURED_LEVEL LEVEL_VALUE and is the first defined value of CONFIGURED_LEVEL
followed by DERIVED_LEVEL. Second, it is possible for nodes to be followed by DERIVED_LEVEL. Second, it is possible for nodes to be
more than one level apart to form adjacencies if any of the nodes more than one level apart to form adjacencies if any of the nodes
is at least LEAF_ONLY. is at least LEAF_ONLY.
Valid Offered Level (VOL): Valid Offered Level (VOL):
A neighbor's level received in a valid LIE (i.e. passing all A neighbor's level received in a valid LIE (i.e., passing all
checks for adjacency formation while disregarding all clauses checks for adjacency formation while disregarding all clauses
involving level values) persisting for the duration of the involving level values) persisting for the duration of the
holdtime interval on the LIE. Observe that offers from nodes holdtime interval on the LIE. Observe that offers from nodes
offering level value of _leaf_level_ do not constitute VOLs (since offering the level value of _leaf_level_ do not constitute VOLs
no valid DERIVED_LEVEL can be obtained from those and consequently (since no valid DERIVED_LEVEL can be obtained from those and
_not_a_ztp_offer_ flag MUST be ignored). Offers from LIEs with consequently the _not_a_ztp_offer_ flag MUST be ignored). Offers
_not_a_ztp_offer_ being true are not VOLs either. If a node from LIEs with _not_a_ztp_offer_ being true are not VOLs either.
maintains parallel adjacencies to the neighbor, VOL on each If a node maintains parallel adjacencies to the neighbor, VOL on
adjacency is considered as equivalent, i.e. the newest VOL from each adjacency is considered as equivalent, i.e., the newest VOL
any such adjacency updates the VOL received from the same node. from any such adjacency updates the VOL received from the same
node.
Highest Available Level (HAL): Highest Available Level (HAL):
Highest defined level value received from all VOLs received. Highest-defined level value received from all VOLs received.
Highest Available Level Systems (HALS): Highest Available Level Systems (HALS):
Set of nodes offering HAL VOLs. Set of nodes offering HAL VOLs.
Highest Adjacency ThreeWay (HAT): Highest Adjacency ThreeWay (HAT):
Highest neighbor level of all the formed _ThreeWay_ adjacencies Highest neighbor level of all the formed _ThreeWay_ adjacencies
for the node. for the node.
6.7.2. Automatic System ID Selection 6.7.2. Automatic System ID Selection
RIFT nodes require a 64-bit System ID which SHOULD be derived as RIFT nodes require a 64-bit System ID that SHOULD be derived as
EUI-64 MA-L derive according to [EUI64]. The organizationally EUI-64 MAC Address Block Large (MA-L) according to [EUI64]. The
governed portion of this ID (24 bits) can be used to generate organizationally governed portion of this ID (24 bits) can be used to
multiple IDs if required to indicate more than one RIFT instance. generate multiple IDs if required to indicate more than one RIFT
instance.
As matter of operational concern, the router MUST ensure that such As matter of operational concern, the router MUST ensure that such
identifier is not changing very frequently (or at least not without identifier is not changing very frequently (or at least not without
sending all its TIEs with fairly short lifetimes, i.e. purging them) sending all its TIEs with fairly short lifetimes, i.e., purging them)
since otherwise the network may be left with large amounts of stale since the network may otherwise be left with large amounts of stale
TIEs in other nodes (though this is not necessarily a serious problem TIEs in other nodes (though this is not necessarily a serious problem
if the procedures described in Section 9 are implemented). if the procedures described in Section 9 are implemented).
6.7.3. Generic Fabric Example 6.7.3. Generic Fabric Example
ZTP forces considerations of an incorrectly or unusually cabled ZTP forces considerations of an incorrectly or unusually cabled
fabric and how such a topology can be forced into a "lattice" fabric and how such a topology can be forced into a "lattice"
structure which a fabric represents (with further restrictions). A structure that a fabric represents (with further restrictions). A
necessary and sufficient physical cabling is shown in Figure 28. The necessary and sufficient physical cabling is shown in Figure 28. The
assumption here is that all nodes are in the same PoD. assumption here is that all nodes are in the same PoD.
+---+ +---+
| A | s = TOP_OF_FABRIC | A | s = TOP_OF_FABRIC
| s | L = LEAF_ONLY | s | L = LEAF_ONLY
++-++ L2L = LEAF_2_LEAF ++-++ L2L = LEAF_2_LEAF
| | | |
+--+ +--+ +--+ +--+
| | | |
skipping to change at page 98, line 38 skipping to change at line 4368
+-----------------+ | | +-----------------+ | |
| | | | | | | | | |
++-++ ++-++ | ++-++ ++-++ |
| X +-----+ Y +-+ | X +-----+ Y +-+
|L2L| | L | |L2L| | L |
+---+ +---+ +---+ +---+
Figure 28: Generic ZTP Cabling Considerations Figure 28: Generic ZTP Cabling Considerations
First, RIFT must anchor the "top" of the cabling and that's what the First, RIFT must anchor the "top" of the cabling and that's what the
TOP_OF_FABRIC flag at node A is for. Then things look smooth until TOP_OF_FABRIC flag at node A is for. Then, things look smooth until
the protocol has to decide whether node Y is at the same level as I, the protocol has to decide whether node Y is at the same level as I,
J (and as consequence, X is south of it) or at the same level as X. J (and as consequence, X is south of it), or X. This is unresolvable
This is unresolvable here until we "nail down the bottom" of the here until we "nail down the bottom" of the topology. To achieve
topology. To achieve that the protocol chooses to use in this that, the protocol chooses to use the leaf flags in X and Y in this
example the leaf flags in X and Y. In case where Y would not have a example. In the case where Y does not have a leaf flag, it will try
leaf flag it will try to elect highest level offered and end up being to elect the highest level offered and end up being in same level as
in same level as I and J. I and J.
6.7.4. Level Determination Procedure 6.7.4. Level Determination Procedure
A node starting up with UNDEFINED_VALUE (i.e. without a A node starting up with UNDEFINED_VALUE (i.e., without a
CONFIGURED_LEVEL or any leaf or TOP_OF_FABRIC flag) MUST follow those CONFIGURED_LEVEL or any leaf or TOP_OF_FABRIC flag) MUST follow these
additional procedures: additional procedures:
1. It advertises its LEVEL_VALUE on all LIEs (observe that this can 1. It advertises its LEVEL_VALUE on all LIEs (observe that this can
be UNDEFINED_LEVEL which in terms of the schema is simply an be UNDEFINED_LEVEL, which in terms of the schema, is simply an
omitted optional value). omitted optional value).
2. It computes HAL as numerically highest available level in all 2. It computes HAL as the numerically highest available level in all
VOLs. VOLs.
3. It chooses then MAX(HAL-1,0) as its DERIVED_LEVEL. The node then 3. Then, it chooses MAX(HAL-1,0) as its DERIVED_LEVEL. The node
starts to advertise this derived level. then starts to advertise this derived level.
4. A node that lost all adjacencies with HAL value MUST hold down 4. A node that lost all adjacencies with the HAL value MUST hold
computation of new DERIVED_LEVEL for at least one second unless down computation of the new DERIVED_LEVEL for at least one second
it has no VOLs from southbound adjacencies. After the holddown unless it has no VOLs from southbound adjacencies. After the
timer expired, it MUST discard all received offers, recompute holddown timer expired, it MUST discard all received offers,
DERIVED_LEVEL and announce it to all neighbors. recompute DERIVED_LEVEL, and announce it to all neighbors.
5. A node MUST reset any adjacency that has changed the level it is 5. A node MUST reset any adjacency that has changed the level it is
offering and is in _ThreeWay_ state. offering and is in _ThreeWay_ state.
6. A node that changed its defined level value MUST readvertise its 6. A node that changed its defined level value MUST re-advertise its
own TIEs (since the new _PacketHeader_ will contain a different own TIEs (since the new _PacketHeader_ will contain a different
level than before). The sequence number of each TIE MUST be level than before). The sequence number of each TIE MUST be
increased. increased.
7. After a level has been derived the node MUST set the 7. After a level has been derived, the node MUST set the
_not_a_ztp_offer_ on LIEs towards all systems offering a VOL for _not_a_ztp_offer_ on LIEs towards all systems offering a VOL for
HAL. HAL.
8. A node that changed its level SHOULD flush from its link state 8. A node that changed its level SHOULD flush TIEs of all other
database TIEs of all other nodes, otherwise stale information may nodes from its link state database; otherwise, stale information
persist on "direction reversal", i.e., nodes that seemed south may persist on "direction reversal", i.e., nodes that seemed
are now north or east-west. This will not prevent the correct south are now north or east-west. This will not prevent the
operation of the protocol but could be slightly confusing correct operation of the protocol but could be slightly confusing
operationally. operationally.
A node starting with LEVEL_VALUE being 0 (i.e., it assumes a leaf A node starting with LEVEL_VALUE being 0 (i.e., it assumes a leaf
function by being configured with the appropriate flags or has a function by being configured with the appropriate flags or has a
CONFIGURED_LEVEL of 0) MUST follow those additional procedures: CONFIGURED_LEVEL of 0) MUST follow this additional procedure:
1. It computes HAT per procedures above but does *not* use it to 1. It computes HAT per the procedures above but does *not* use it to
compute DERIVED_LEVEL. HAT is used to limit adjacency formation compute DERIVED_LEVEL. HAT is used to limit adjacency formation
per Section 6.2. per Section 6.2.
It MAY also follow modified procedures: It MAY also follow this modified procedure:
1. It may pick a different strategy to choose VOL, e.g. use the VOL 1. It may pick a different strategy to choose VOL, e.g., use the VOL
value with highest number of VOLs. Such strategies are only value with highest number of VOLs. Such strategies are only
possible since the node always remains "at the bottom of the possible since the node always remains "at the bottom of the
fabric" while another layer could "invert" the fabric by picking fabric", while another layer could "invert" the fabric by picking
its preferred VOL in a different fashion rather than always its preferred VOL in a different fashion rather than always
trying to achieve the highest viable level. trying to achieve the highest viable level.
6.7.5. RIFT ZTP FSM 6.7.5. RIFT ZTP FSM
This section specifies the precise, normative ZTP FSM and can be This section specifies the precise, normative ZTP FSM and can be
omitted unless the reader is pursuing an implementation of the omitted unless the reader is pursuing an implementation of the
protocol. For additional clarity a graphical representation of the protocol. For additional clarity, a graphical representation of the
ZTP FSM is depicted in Figure 29. It may also be helpful to refer to ZTP FSM is depicted in Figure 29. It may also be helpful to refer to
the normative schema in Section 7. the normative schema in Section 7.
Initial state is ComputeBestOffer. The initial state is ComputeBestOffer.
Enter Enter
| |
v v
+------------------+ +------------------+
| ComputeBestOffer | | ComputeBestOffer |
| |<----+ | |<----+
| | | BetterHAL | | | BetterHAL
| | | BetterHAT | | | BetterHAT
| | | ChangeLocalConfiguredLevel | | | ChangeLocalConfiguredLevel
skipping to change at page 101, line 39 skipping to change at line 4514
| | | ShortTic | | | ShortTic
| |-----+ | |-----+
+------------------+ +------------------+
| |
| LostHAL | LostHAL
V V
(HoldingDown) (HoldingDown)
Figure 29: RIFT ZTP FSM Figure 29: RIFT ZTP FSM
The following words are used for well-known procedures: The following terms are used for well-known procedures:
* PUSH Event: queues an event to be executed by the FSM upon exit of * PUSH Event: queues an event to be executed by the FSM upon exit of
this action this action
* COMPARE_OFFERS: checks whether based on current offers and held * COMPARE_OFFERS: checks whether, based on current offers and held
last results, the events BetterHAL/LostHAL/BetterHAT/LostHAT are last results, the events BetterHAL/LostHAL/BetterHAT/LostHAT are
necessary and returns them necessary and returns them
* UPDATE_OFFER: store current offer with adjacency holdtime as * UPDATE_OFFER: store current offer with adjacency holdtime as
lifetime and COMPARE_OFFERS, then PUSH corresponding events lifetime and COMPARE_OFFERS, then PUSH corresponding events
* LEVEL_COMPUTE: compute best offered or configured level and HAL/ * LEVEL_COMPUTE: compute best offered or configured level and HAL/
HAT, if anything changed PUSH ComputationDone HAT, if anything changed, PUSH ComputationDone
* REMOVE_OFFER: remove the corresponding offer and COMPARE_OFFERS, * REMOVE_OFFER: remove the corresponding offer and COMPARE_OFFERS,
PUSH corresponding events PUSH corresponding events
* PURGE_OFFERS: REMOVE_OFFER for all held offers, COMPARE OFFERS, * PURGE_OFFERS: REMOVE_OFFER for all held offers, COMPARE OFFERS,
PUSH corresponding events PUSH corresponding events
* PROCESS_OFFER: * PROCESS_OFFER:
1. if no level offered then REMOVE_OFFER 1. if no level is offered, then REMOVE_OFFER
2. else 2. else
1. if offered level > leaf then UPDATE_OFFER a. if offered level > leaf, then UPDATE_OFFER
2. else REMOVE_OFFER b. else REMOVE_OFFER
States: States:
* ComputeBestOffer: processes received offers to derive ZTP * ComputeBestOffer: Processes received offers to derive ZTP
variables variables.
* HoldingDown: holding down while receiving updates * HoldingDown: Holding down while receiving updates.
* UpdatingClients: updates other FSMs on the same node with * UpdatingClients: Updates other FSMs on the same node with
computation results computation results.
Events: Events:
* ChangeLocalHierarchyIndications: node locally configured with new * ChangeLocalHierarchyIndications: Node locally configured with new
leaf flags. leaf flags.
* ChangeLocalConfiguredLevel: node locally configured with a defined * ChangeLocalConfiguredLevel: Node locally configured with a defined
level level.
* NeighborOffer: a new neighbor offer with optional level and * NeighborOffer: A new neighbor offer with optional level and
neighbor state. neighbor state.
* BetterHAL: better HAL computed internally. * BetterHAL: Better HAL computed internally.
* BetterHAT: better HAT computed internally. * BetterHAT: Better HAT computed internally.
* LostHAL: lost last HAL in computation. * LostHAL: Lost last HAL in computation.
* LostHAT: lost HAT in computation. * LostHAT: Lost HAT in computation.
* ComputationDone: computation performed. * ComputationDone: Computation performed.
* HoldDownExpired: holddown timer expired. * HoldDownExpired: Holddown timer expired.
* ShortTic: one-second timer tick. This event is provided to the * ShortTic: One-second timer tick. This event is provided to the
FSM once a second by an implementation-specific mechanism that is FSM once a second by an implementation-specific mechanism that is
outside the scope of this specification. This event is quietly outside the scope of this specification. This event is quietly
ignored if the relevant transition does not exist. ignored if the relevant transition does not exist.
Actions: Actions:
* on ChangeLocalConfiguredLevel in HoldingDown finishes in * on ChangeLocalConfiguredLevel in HoldingDown finishes in
ComputeBestOffer: store configured level ComputeBestOffer: store configured level
* on BetterHAT in HoldingDown finishes in HoldingDown: no action * on BetterHAT in HoldingDown finishes in HoldingDown: no action
* on ShortTic in HoldingDown finishes in HoldingDown: remove expired * on ShortTic in HoldingDown finishes in HoldingDown: remove expired
offers and if holddown timer expired PUSH_EVENT HoldDownExpired offers, and if holddown timer expired, PUSH_EVENT HoldDownExpired
* on NeighborOffer in HoldingDown finishes in HoldingDown: * on NeighborOffer in HoldingDown finishes in HoldingDown:
PROCESS_OFFER PROCESS_OFFER
* on ComputationDone in HoldingDown finishes in HoldingDown: no * on ComputationDone in HoldingDown finishes in HoldingDown: no
action action
* on BetterHAL in HoldingDown finishes in HoldingDown: no action * on BetterHAL in HoldingDown finishes in HoldingDown: no action
* on LostHAT in HoldingDown finishes in HoldingDown: no action * on LostHAT in HoldingDown finishes in HoldingDown: no action
skipping to change at page 104, line 6 skipping to change at line 4624
* on NeighborOffer in ComputeBestOffer finishes in ComputeBestOffer: * on NeighborOffer in ComputeBestOffer finishes in ComputeBestOffer:
PROCESS_OFFER PROCESS_OFFER
* on BetterHAT in ComputeBestOffer finishes in ComputeBestOffer: * on BetterHAT in ComputeBestOffer finishes in ComputeBestOffer:
LEVEL_COMPUTE LEVEL_COMPUTE
* on ChangeLocalHierarchyIndications in ComputeBestOffer finishes in * on ChangeLocalHierarchyIndications in ComputeBestOffer finishes in
ComputeBestOffer: store leaf flags and LEVEL_COMPUTE ComputeBestOffer: store leaf flags and LEVEL_COMPUTE
* on LostHAL in ComputeBestOffer finishes in HoldingDown: if any * on LostHAL in ComputeBestOffer finishes in HoldingDown: if any
southbound adjacencies present then update holddown timer to southbound adjacencies present, then update holddown timer to
normal duration else fire holddown timer immediately normal duration, else fire holddown timer immediately
* on ShortTic in ComputeBestOffer finishes in ComputeBestOffer: * on ShortTic in ComputeBestOffer finishes in ComputeBestOffer:
remove expired offers remove expired offers
* on ComputationDone in ComputeBestOffer finishes in * on ComputationDone in ComputeBestOffer finishes in
UpdatingClients: no action UpdatingClients: no action
* on ChangeLocalConfiguredLevel in ComputeBestOffer finishes in * on ChangeLocalConfiguredLevel in ComputeBestOffer finishes in
ComputeBestOffer: store configured level and LEVEL_COMPUTE ComputeBestOffer: store configured level and LEVEL_COMPUTE
* on BetterHAL in ComputeBestOffer finishes in ComputeBestOffer: * on BetterHAL in ComputeBestOffer finishes in ComputeBestOffer:
LEVEL_COMPUTE LEVEL_COMPUTE
* on ShortTic in UpdatingClients finishes in UpdatingClients: remove * on ShortTic in UpdatingClients finishes in UpdatingClients: remove
expired offers expired offers
* on LostHAL in UpdatingClients finishes in HoldingDown: if any * on LostHAL in UpdatingClients finishes in HoldingDown: if any
southbound adjacencies are present then update holddown timer to southbound adjacencies are present, then update holddown timer to
normal duration else fire holddown timer immediately normal duration, else fire holddown timer immediately
* on BetterHAT in UpdatingClients finishes in ComputeBestOffer: no * on BetterHAT in UpdatingClients finishes in ComputeBestOffer: no
action action
* on BetterHAL in UpdatingClients finishes in ComputeBestOffer: no * on BetterHAL in UpdatingClients finishes in ComputeBestOffer: no
action action
* on ChangeLocalConfiguredLevel in UpdatingClients finishes in * on ChangeLocalConfiguredLevel in UpdatingClients finishes in
ComputeBestOffer: store configured level ComputeBestOffer: store configured level
skipping to change at page 105, line 40 skipping to change at line 4704
| | | | | |
+---------+ | | +---------+ | |
| | | | | |
++-++ +---+ | ++-++ +---+ |
| X | | Y +-+ | X | | Y +-+
| 0 | | 0 | | 0 | | 0 |
+---+ +---+ +---+ +---+
Figure 30: Generic ZTP Topology Autoconfigured Figure 30: Generic ZTP Topology Autoconfigured
In case where the LEAF_ONLY restriction on Y is removed the outcome In the case where the LEAF_ONLY restriction on Y is removed, the
would be very different however and result in Figure 31. This outcome would be very different however and result in Figure 31.
demonstrates basically that auto configuration makes miscabling This basically demonstrates that autoconfiguration makes miscabling
detection hard and with that can lead to undesirable effects in cases detection hard and, with that, can lead to undesirable effects in
where leaves are not "nailed" by the appropriately configured flags cases where leaves are not "nailed" by the appropriately configured
and arbitrarily cabled. flags and arbitrarily cabled.
+---+ +---+
| A | | A |
| 24| | 24|
++-++ ++-++
| | | |
+--+ +--+ +--+ +--+
| | | |
+--++ ++--+ +--++ ++--+
| E | | F | | E | | F |
skipping to change at page 106, line 41 skipping to change at line 4747
| X +--------+ | X +--------+
| 0 | | 0 |
+---+ +---+
Figure 31: Generic ZTP Topology Autoconfigured Figure 31: Generic ZTP Topology Autoconfigured
6.8. Further Mechanisms 6.8. Further Mechanisms
6.8.1. Route Preferences 6.8.1. Route Preferences
Since RIFT distinguishes between different route types such as e.g. Since RIFT distinguishes between different route types, such as
external routes from other protocols and additionally advertises external routes from other protocols, and additionally advertises
special types of routes on disaggregation, the protocol MUST tie- special types of routes on disaggregation, the protocol MUST tie-
break internally different types on a clear preference scale to break internally different types on a clear preference scale to
prevent traffic loss or loops. The preferences are given in the prevent traffic loss or loops. The preferences are given in the
schema type _RouteType_. schema type _RouteType_.
Table 5 contains the route type as derived from the TIE type carrying Table 5 contains the route type as derived from the TIE type carrying
it. Entries are sorted from the most preferred route type to the it. Entries are sorted from the most preferred route type to the
least preferred route type. least preferred route type.
+==================================+======================+ +==================================+======================+
skipping to change at page 107, line 33 skipping to change at line 4786
| South External Prefix and South | SouthExternalPrefix | | South External Prefix and South | SouthExternalPrefix |
| Positive External Disaggregation | | | Positive External Disaggregation | |
+----------------------------------+----------------------+ +----------------------------------+----------------------+
| South Negative Prefix | NegativeSouthPrefix | | South Negative Prefix | NegativeSouthPrefix |
+----------------------------------+----------------------+ +----------------------------------+----------------------+
Table 5: TIEs and Contained Route Types Table 5: TIEs and Contained Route Types
6.8.2. Overload Bit 6.8.2. Overload Bit
Overload attribute is specified in the packet encoding schema The overload attribute is specified in the packet encoding schema
(Section 7) in the _overload_ flag. (Section 7) in the _overload_ flag.
The overload flag MUST be respected by all necessary SPF The overload flag MUST be respected by all necessary SPF
computations. A node with the overload flag set SHOULD advertise all computations. A node with the overload flag set SHOULD advertise all
locally hosted prefixes both northbound and southbound, all other locally hosted prefixes, both northbound and southbound; all other
southbound prefixes SHOULD NOT be advertised. southbound prefixes SHOULD NOT be advertised.
Leaf nodes SHOULD set the overload attribute on all originated Node Leaf nodes SHOULD set the overload attribute on all originated Node
TIEs. If spine nodes were to forward traffic not intended for the TIEs. If spine nodes were to forward traffic not intended for the
local node, the leaf node would not be able to prevent routing/ local node, the leaf node would not be able to prevent routing/
forwarding loops as it does not have the necessary topology forwarding loops as it does not have the necessary topology
information to do so. information to do so.
6.8.3. Optimized Route Computation on Leaves 6.8.3. Optimized Route Computation on Leaves
Leaf nodes only have visibility to directly connected nodes and Leaf nodes only have visibility to directly connected nodes and
therefore are not required to run "full" SPF computations. Instead, therefore are not required to run "full" SPF computations. Instead,
prefixes from neighboring nodes can be gathered to run a "partial" prefixes from neighboring nodes can be gathered to run a "partial"
SPF computation in order to build the routing table. SPF computation in order to build the routing table.
Leaf nodes SHOULD only hold their own N-TIEs, and in cases of L2L Leaf nodes SHOULD only hold their own N-TIEs and, in cases of L2L
implementations, the N-TIEs of their East/West neighbors. Leaf nodes implementations, the N-TIEs of their East-West neighbors. Leaf nodes
MUST hold all S-TIEs from their neighbors. MUST hold all S-TIEs from their neighbors.
Normally, a full network graph is created based on local N-TIEs and Normally, a full network graph is created based on local N-TIEs and
remote S-TIEs that it receives from neighbors, at which time, remote S-TIEs that it receives from neighbors, at which time,
necessary SPF computations are performed. Instead, leaf nodes can necessary SPF computations are performed. Instead, leaf nodes can
simply compute the minimum cost and next-hop set of each leaf simply compute the minimum cost and next-hop set of each leaf
neighbor by examining its local adjacencies. Associated N-TIEs are neighbor by examining its local adjacencies. Associated N-TIEs are
used to determine bi-directionality and derive the next-hop set. used to determine bidirectionality and derive the next-hop set. The
Cost is then derived from the minimum cost of the local adjacency to cost is then derived from the minimum cost of the local adjacency to
the neighbor and the prefix cost. the neighbor and the prefix cost.
Leaf nodes would then attach necessary prefixes as described in Leaf nodes would then attach necessary prefixes as described in
Section 6.6. Section 6.6.
6.8.4. Mobility 6.8.4. Mobility
The RIFT control plane MUST maintain the real time status of every The RIFT control plane MUST maintain the real time status of every
prefix, to which port it is attached, and to which leaf node that prefix, to which port it is attached, and to which leaf node that
port belongs. This is still true in cases of IP mobility where the port belongs. This is still true in cases of IP mobility where the
point of attachment may change several times a second. point of attachment may change several times a second.
There are two classic approaches to explicitly maintain this There are two classic approaches to explicitly maintain this
information, "timestamp" and "sequence counter" as follows: information, "timestamp" and "sequence counter", which are defined as
follows:
timestamp: timestamp:
With this method, the infrastructure SHOULD record the precise With this method, the infrastructure SHOULD record the precise
time at which the movement is observed. One key advantage of this time at which the movement is observed. One key advantage of this
technique is that it has no dependency on the mobile device. One technique is that it has no dependency on the mobile device. One
drawback is that the infrastructure MUST be precisely synchronized drawback is that the infrastructure MUST be precisely synchronized
in order to be able to compare timestamps as the points of in order to be able to compare timestamps as the points of
attachment change. This could be accomplished by utilizing attachment change. This could be accomplished by utilizing the
Precision Time Protocol (PTP) IEEE Std. 1588 [IEEEstd1588] or Precision Time Protocol (PTP) (IEEE Std. 1588 [IEEEstd1588] or
802.1AS [IEEEstd8021AS] which is designed for bridged LANs. Both 802.1AS [IEEEstd8021AS]), which is designed for bridged LANs.
the precision of the synchronization protocol and the resolution Both the precision of the synchronization protocol and the
of the timestamp must beat the shortest possible roaming time on resolution of the timestamp must beat the shortest possible
the fabric. Another drawback is that the presence of a mobile roaming time on the fabric. Another drawback is that the presence
device may only be observed asynchronously, such as when it starts of a mobile device may only be observed asynchronously, such as
using an IP protocol like ARP [RFC0826], IPv6 Neighbor Discovery when it starts using an IP protocol like ARP [RFC0826], IPv6
[RFC4861], IPv6 Stateless Address Configuration [RFC4862], DHCP Neighbor Discovery [RFC4861], IPv6 Stateless Address Configuration
[RFC2131], or DHCPv6 [RFC8415]. [RFC4862], DHCP [RFC2131], or DHCPv6 [RFC8415].
sequence counter: sequence counter:
With this method, a mobile device notifies its point of attachment With this method, a mobile device notifies its point of attachment
on arrival with a sequence counter that is incremented upon each on arrival with a sequence counter that is incremented upon each
movement. On the positive side, this method does not have a movement. On the positive side, this method does not have a
dependency on a precise sense of time, since the sequence of dependency on a precise sense of time, since the sequence of
movements is kept in order by the mobile device. The disadvantage movements is kept in order by the mobile device. The disadvantage
of this approach is the need for support for protocols that may be of this approach is the need for support for protocols that may be
used by the mobile device to register its presence to the leaf used by the mobile device to register its presence to the leaf
node with the capability to provide a sequence counter. Well- node with the capability to provide a sequence counter. Well-
known issues with sequence counters such as wrapping and known issues with sequence counters, such as wrapping and
comparison rules MUST be addressed properly. Sequence numbers comparison rules, MUST be addressed properly. Sequence numbers
MUST be compared by a single homogenous source to make operation MUST be compared by a single homogenous source to make operation
feasible. Sequence number comparison from multiple heterogeneous feasible. Sequence number comparison from multiple heterogeneous
sources would be extremely difficult to implement. sources would be extremely difficult to implement.
RIFT supports a hybrid approach by using an optional RIFT supports a hybrid approach by using an optional
'PrefixSequenceType' attribute (that is also called a 'PrefixSequenceType' attribute (which is also called a
_monotonic_clock_ in the schema) that consists of a timestamp and _monotonic_clock_ in the schema) that consists of a timestamp and
optional sequence number field. In case of a negatively distributed optional sequence number field. In case of a negatively distributed
prefix this attribute MUST NOT be included by the originator and it prefix, this attribute MUST NOT be included by the originator and it
MUST be ignored by all nodes during computation. When this attribute MUST be ignored by all nodes during computation. When this attribute
is present (observe that per data schema the attribute itself is is present (observe that per data schema, the attribute itself is
optional but in case it is included the 'timestamp' field is optional, but in case it is included, the "timestamp" field is
required): required):
* The leaf node MAY advertise a timestamp of the latest sighting of * The leaf node MAY advertise a timestamp of the latest sighting of
a prefix, e.g., by snooping IP protocols or the node using the a prefix, e.g., by snooping IP protocols or the node using the
time at which it advertised the prefix. RIFT transports the time at which it advertised the prefix. RIFT transports the
timestamp within the desired Prefix North TIEs as [IEEEstd1588] timestamp within the desired Prefix North TIEs as the
timestamp. [IEEEstd1588] timestamp.
* RIFT MAY interoperate with "Registration Extensions for 6LoWPAN * RIFT MAY interoperate with "Registration Extensions for 6LoWPAN
Neighbor Discovery" [RFC8505], which provides a method for Neighbor Discovery" [RFC8505], which provides a method for
registering a prefix with a sequence number called a Transaction registering a prefix with a sequence number called a Transaction
ID (TID). In such cases, RIFT SHOULD transport the derived TID ID (TID). In such cases, RIFT SHOULD transport the derived TID
without modification. without modification.
* RIFT also defines an abstract negative clock (ASNC) (also called * RIFT also defines an abstract negative clock (ASNC) (also called
an 'undefined' clock). The ASNC MUST be considered older than any an "undefined" clock). The ASNC MUST be considered older than any
other defined clock. By default, when a node receives a Prefix other defined clock. By default, when a node receives a Prefix
North TIE that does not contain a 'PrefixSequenceType' attribute, North TIE that does not contain a 'PrefixSequenceType' attribute,
it MUST interpret the absence as the ASNC. it MUST interpret the absence as the ASNC.
* Any prefix present on the fabric in multiple nodes that have the * Any prefix present on the fabric in multiple nodes that have the
*same* clock is considered as anycast. *same* clock is considered as anycast.
* RIFT specification assumes that all nodes are being synchronized * The RIFT specification assumes that all nodes are being
within at least 200 milliseconds or less. This is achievable synchronized within at least 200 milliseconds or less. This is
through the use of NTP [RFC5905]. An implementation MAY provide a achievable through the use of NTP [RFC5905]. An implementation
way to reconfigure a domain to a different value, and provides for MAY provide a way to reconfigure a domain to a different value and
this purpose a variable called MAXIMUM_CLOCK_DELTA. provides a variable called MAXIMUM_CLOCK_DELTA for this purpose.
6.8.4.1. Clock Comparison 6.8.4.1. Clock Comparison
All monotonic clock values MUST be compared to each other using the All monotonic clock values MUST be compared to each other using the
following rules: following rules:
1. The ASNC is older than any other value except ASNC *and* 1. The ASNC is older than any other value except ASNC,
2. Clocks with timestamp differing by more than MAXIMUM_CLOCK_DELTA 2. Clocks with timestamps differing by more than MAXIMUM_CLOCK_DELTA
are comparable by using the timestamps only *and* are comparable by using the timestamps only,
3. Clocks with timestamps differing by less than MAXIMUM_CLOCK_DELTA 3. Clocks with timestamps differing by less than MAXIMUM_CLOCK_DELTA
are comparable by using their TIDs only *and* are comparable by using their TIDs only, *and*
4. An undefined TID is always older than any other TID *and* 4. An undefined TID is always older than any other TID, *and*
5. TIDs are compared using rules of [RFC8505]. 5. TIDs are compared using rules of [RFC8505].
6.8.4.2. Interaction between Time Stamps and Sequence Counters 6.8.4.2. Interaction Between Timestamps and Sequence Counters
For attachment changes that occur less frequently (e.g., once per For attachment changes that occur less frequently (e.g., once per
second), the timestamp that the RIFT infrastructure captures should second), the timestamp that the RIFT infrastructure captures should
be enough to determine the most current discovery. If the point of be enough to determine the most current discovery. If the point of
attachment changes faster than the maximum drift of the time stamping attachment changes faster than the maximum drift of the timestamping
mechanism (i.e., MAXIMUM_CLOCK_DELTA), then a sequence number SHOULD mechanism (i.e., MAXIMUM_CLOCK_DELTA), then a sequence number SHOULD
be used to enable necessary precision to determine currency. be used to enable necessary precision to determine currency.
The sequence counter in [RFC8505] is encoded as one octet and wraps The sequence counter in [RFC8505] is encoded as one octet and wraps
around using Appendix A. around using Appendix A.
Within the resolution of MAXIMUM_CLOCK_DELTA, sequence counter values Within the resolution of MAXIMUM_CLOCK_DELTA, sequence counter values
captured during 2 sequential iterations of the same timestamp SHOULD captured during 2 sequential iterations of the same timestamp SHOULD
be comparable. This means that with default values, a node may move be comparable. This means that with default values, a node may move
up to 127 times in a 200-millisecond period and the clocks will up to 127 times in a 200-millisecond period and the clocks will
remain comparable. This allows the RIFT infrastructure to explicitly remain comparable. This allows the RIFT infrastructure to explicitly
assert the most up-to-date advertisement. assert the most up-to-date advertisement.
6.8.4.3. Anycast vs. Unicast 6.8.4.3. Anycast vs. Unicast
A unicast prefix can be attached to at most one leaf, whereas an A unicast prefix can be attached to one leaf at most, whereas an
anycast prefix may be reachable via more than one leaf. anycast prefix may be reachable via more than one leaf.
If a monotonic clock attribute is provided on the prefix, then the If a monotonic clock attribute is provided on the prefix, then the
prefix with the *newest* clock value is strictly preferred. An prefix with the *newest* clock value is strictly preferred. An
anycast prefix does not carry a clock or all clock attributes MUST be anycast prefix does not carry a clock, or all clock attributes MUST
the same under the rules of Section 6.8.4.1. be the same under the rules of Section 6.8.4.1.
It is important that in mobility events the leaf is re-flooding as In mobility events, it is important that the leaf is reflooding as
quickly as possible to communicate the absence of the prefix that quickly as possible to communicate the absence of the prefix that
moved. moved.
Without support for [RFC8505] movements on the fabric within Without support for [RFC8505], movements on the fabric within
intervals smaller than 100msec will be interpreted as anycast. intervals smaller than 100 msec will be interpreted as anycast.
6.8.4.4. Overlays and Signaling 6.8.4.4. Overlays and Signaling
RIFT is agnostic to any overlay technologies and their associated RIFT is agnostic to any overlay technologies and their associated
control and transports that run on top of it (e.g. VXLAN). It is control and transports that run on top of it (e.g., Virtual
expected that leaf nodes and possibly ToF nodes can perform necessary eXtensible Local Area Network (VXLAN)). It is expected that leaf
data plane encapsulation. nodes and possibly ToF nodes can perform necessary data plane
encapsulation.
In the context of mobility, overlays provide another possible In the context of mobility, overlays provide another possible
solution to avoid injecting mobile prefixes into the fabric as well solution to avoid injecting mobile prefixes into the fabric as well
as improving scalability of the deployment. It makes sense to as improving scalability of the deployment. It makes sense to
consider overlays for mobility solutions in IP fabrics. As an consider overlays for mobility solutions in IP fabrics. As an
example, a mobility protocol such as LISP [RFC9300] [RFC9301] may example, a mobility protocol such as the Locator/ID Separation
inform the ingress leaf of the location of the egress leaf in real Protocol (LISP) [RFC9300] [RFC9301] may inform the ingress leaf of
time. the location of the egress leaf in real time.
Another possibility is to consider that mobility as an underlay Another possibility is to consider that mobility is an underlay
service and support it in RIFT to an extent. The load on the fabric service and support it in RIFT to an extent. The load on the fabric
increases with the amount of mobility obviously since a move forces increases with the amount of mobility since a move forces flooding
flooding and computation on all nodes in the scope of the move so and computation on all nodes in the scope of the move so tunneling
tunneling from leaf to the ToF may be desired to speed up convergence from the leaf to the ToF may be desired to speed up convergence
times. times.
6.8.5. Key/Value (KV) Store 6.8.5. Key/Value (KV) Store
6.8.5.1. Southbound 6.8.5.1. Southbound
RIFT supports the southbound distribution of key-value pairs that can RIFT supports the southbound distribution of key-value pairs that can
be used to distribute information to facilitate higher levels of be used to distribute information to facilitate higher levels of
functionality (e.g. distribution of configuration information). KV functionality (e.g., distribution of configuration information). KV
South TIEs may arrive from multiple nodes and therefore MUST execute South TIEs may arrive from multiple nodes and therefore MUST execute
the following tie-breaking rules for each key: the following tie-breaking rules for each key:
1. Only KV TIEs received from nodes to which a bi-directional 1. Only KV TIEs received from nodes to which a bidirectional
adjacency exists MUST be considered. adjacency exists MUST be considered.
2. For each valid KV South TIEs that contains the same key, the 2. For each valid KV South TIEs that contains the same key, the
value within the South TIE with the highest level will be value within the South TIE with the highest level will be
preferred. If the levels are identical, the highest originating preferred. If the levels are identical, the highest originating
System ID will be preferred. In the case of overlapping keys in System ID will be preferred. In the case of overlapping keys in
the winning South TIE, the behavior is undefined. the winning South TIE, the behavior is undefined.
Consider that if a node goes down, nodes south of it will lose Consider that if a node goes down, nodes south of it will lose
associated adjacencies causing them to disregard corresponding KVs. associated adjacencies, causing them to disregard corresponding KVs.
New KV South TIEs are advertised to prevent stale information being New KV South TIEs are advertised to prevent stale information being
used by nodes that are further south. KV advertisements southbound used by nodes that are further south. KV advertisements southbound
are not a result of independent computation by every node over the are not a result of independent computation by every node over the
same set of South TIEs, but a diffused computation. same set of South TIEs but a diffused computation.
6.8.5.2. Northbound 6.8.5.2. Northbound
Certain use cases necessitate distribution of essential KV Certain use cases necessitate distribution of essential KV
information that is generated by the leaves in the northbound information that is generated by the leaves in the northbound
direction. Such information is flooded in KV North TIEs. Since the direction. Such information is flooded in KV North TIEs. Since the
originator of the KV North TIEs is preserved during flooding, the originator of the KV North TIEs is preserved during flooding, the
corresponding mechanism will define, if necessary, tie-breaking rules corresponding mechanism will define, if necessary, tie-breaking rules
depending on the semantics of the information. depending on the semantics of the information.
Only KV TIEs from nodes that are reachable via multiplane Only KV TIEs from nodes that are reachable via multi-plane
reachability computation mentioned in Section 6.5.2.3 SHOULD be reachability computation mentioned in Section 6.5.2.3 SHOULD be
considered. considered.
6.8.6. Interactions with BFD 6.8.6. Interactions with BFD
RIFT MAY incorporate BFD [RFC5881] to react quickly to link failures. RIFT MAY incorporate Bidirectional Forwarding Detection (BFD)
In such case, the following procedures are introduced: [RFC5881] to react quickly to link failures. In such case, the
following procedures are introduced:
After RIFT _ThreeWay_ hello adjacency convergence a BFD session 1. After RIFT _ThreeWay_ hello adjacency convergence, a BFD session
MAY be formed automatically between the RIFT endpoints without MAY be formed automatically between the RIFT endpoints without
further configuration using the exchanged discriminators that are further configuration using the exchanged discriminators that are
equal to the _local_id_ in the _LIEPacket_. The capability of the equal to the _local_id_ in the _LIEPacket_. The capability of the
remote side to support BFD is carried in the LIEs in remote side to support BFD is carried in the LIEs in
_LinkCapabilities_. _LinkCapabilities_.
In case an established BFD session goes Down after it was Up, RIFT 2. In case an established BFD session goes down after it was up,
adjacency SHOULD be re-initialized and subsequently started from RIFT adjacency SHOULD be re-initialized and subsequently started
Init after it receives a consecutive BFD Up. from Init after it receives a consecutive BFD Up.
In case of parallel links between nodes each link MAY run its own 3. In case of parallel links between nodes, each link MAY run its
independent BFD session or they MAY share a session. The specific own independent BFD session or they MAY share a session. The
manner in which this is implemented is outside the scope of this specific manner in which this is implemented is outside the scope
document. of this document.
If link identifiers or BFD capabilities change, both the LIE and 4. If link identifiers or BFD capabilities change, both the LIE and
any BFD sessions SHOULD be brought down and back up again. In any BFD sessions SHOULD be brought down and back up again. In
case only the advertised capabilities change, the node MAY choose case only the advertised capabilities change, the node MAY choose
to persist the BFD session. to persist the BFD session.
Multiple RIFT instances MAY choose to share a single BFD session, 5. Multiple RIFT instances MAY choose to share a single BFD session;
in such cases the behavior for which discriminators are used is in such cases, the behavior for which discriminators are used is
undefined. However, RIFT MAY advertise the same link ID for the undefined. However, RIFT MAY advertise the same link ID for the
same interface in multiple instances to "share" discriminators. same interface in multiple instances to "share" discriminators.
The BFD TTL follows [RFC5082]. 6. The BFD TTL follows [RFC5082].
6.8.7. Fabric Bandwidth Balancing 6.8.7. Fabric Bandwidth Balancing
A well understood problem in fabrics is that, in case of link A well understood problem in fabrics is that, in case of link
failures, it would be ideal to rebalance how much traffic is sent to failures, it would be ideal to rebalance how much traffic is sent to
switches in the next level based on available ingress and egress switches in the next level based on the available ingress and egress
bandwidth. bandwidth.
RIFT supports a light-weight mechanism that can deal with the problem RIFT supports a light-weight mechanism that can deal with the problem
based on the fact that RIFT is loop-free. based on the fact that RIFT is loop-free.
6.8.7.1. Northbound Direction 6.8.7.1. Northbound Direction
Every RIFT node SHOULD compute the amount of northbound bandwidth Every RIFT node SHOULD compute the amount of northbound bandwidth
available through neighbors at a higher level and modify the distance available through neighbors at a higher level and modify the distance
received on default route from these neighbors. The bandwidth is received on the default route from these neighbors. The bandwidth is
advertised in _NodeNeighborsTIEElement_ element which represents the advertised in the _NodeNeighborsTIEElement_ element, which represents
sum of the bandwidths of all the parallel links to a neighbor. the sum of the bandwidths of all the parallel links to a neighbor.
Default routes with differing distances SHOULD be used to support Default routes with differing distances SHOULD be used to support
weighted ECMP forwarding. Such a distance is called Bandwidth weighted ECMP forwarding. Such a distance is called Bandwidth
Adjusted Distance (BAD). This is best illustrated by a simple Adjusted Distance (BAD). This is best illustrated by a simple
example. example.
100 x 100 100 MBits 100 x 100 100 Mbit/s
| x | | | x | |
+-+---+-+ +-+---+-+ +-+---+-+ +-+---+-+
| | | | | | | |
|Spin111| |Spin112| |Spin111| |Spin112|
+-+---+++ ++----+++ +-+---+++ ++----+++
|x || || || |x || || ||
|| |+---------------+ || || |+---------------+ ||
|| +---------------+| || || +---------------+| ||
|| || || || || || || ||
|| || || || || || || ||
-----All Links 10 MBit------- -----All Links 10 Mbit/s-----
|| || || || || || || ||
|| || || || || || || ||
|| +------------+| || || || +------------+| || ||
|| |+------------+ || || || |+------------+ || ||
|x || || || |x || || ||
+-+---+++ +--++-+++ +-+---+++ +--++-+++
| | | | | | | |
|Leaf111| |Leaf112| |Leaf111| |Leaf112|
+-------+ +-------+ +-------+ +-------+
Figure 32: Balancing Bandwidth Figure 32: Balancing Bandwidth
Figure 32 depicts an example topology where links between leaf and Figure 32 depicts an example topology where links between leaf and
spine nodes are 10 MBit/s and links from spine nodes northbound are spine nodes are 10 Mbit/s and links from spine nodes northbound are
100 MBit/s. It includes parallel link failure between Leaf 111 and 100 Mbit/s. It includes parallel link failure between Leaf 111 and
Spine 111 and as a result, Leaf 111 wants to forward more traffic Spine 111, and as a result, Leaf 111 wants to forward more traffic
toward Spine 112. Additionally, it includes as well an uplink towards Spine 112. Additionally, it includes an uplink failure on
failure on Spine 111. Spine 111.
The local modification of the received default route distance from The local modification of the received default route distance from
upper level is achieved by running a relatively simple algorithm the upper level is achieved by running a relatively simple algorithm
where the bandwidth is weighted exponentially, while the distance on where the bandwidth is weighted exponentially, while the distance on
the default route represents a multiplier for the bandwidth weight the default route represents a multiplier for the bandwidth weight
for easy operational adjustments. for easy operational adjustments.
On a node, L, use Node TIEs to compute from each non-overloaded On a node, L, use Node TIEs to compute from each non-overloaded
northbound neighbor N to compute 3 values: northbound neighbor N to compute 3 values:
L_N_u: sum of the bandwidth available from L to N (to account for 1. L_N_u: sum of the bandwidth available from L to N (to account for
parallel links) parallel links)
N_u: sum of the uplink bandwidth available on N 2. N_u: sum of the uplink bandwidth available on N
T_N_u: L_N_u * OVERSUBSCRIPTION_CONSTANT + N_u 3. T_N_u: L_N_u * OVERSUBSCRIPTION_CONSTANT + N_u
For all T_N_u determine the corresponding M_N_u as For all T_N_u, determine the corresponding M_N_u as
log_2(next_power_2(T_N_u)) and determine MAX_M_N_u as maximum value log_2(next_power_2(T_N_u)) and determine MAX_M_N_u as the maximum
of all such M_N_u values. value of all such M_N_u values.
For each advertised default route from a node N modify the advertised For each advertised default route from a node N, modify the
distance D to BAD = D * (1 + MAX_M_N_u - M_N_u) and use BAD instead advertised distance D to BAD = D * (1 + MAX_M_N_u - M_N_u) and use
of distance D to weight balance default forwarding towards N. BAD instead of distance D to balance the weight of the default
forwarding towards N.
For the example above, a simple table of values will help in For the example above, a simple table of values will help in
understanding of the concept. The implicit assumption here is that understanding the concept. The implicit assumption here is that all
all default route distances are advertised with D=1 and that default route distances are advertised with D=1 and that
OVERSUBSCRIPTION_CONSTANT = 1. OVERSUBSCRIPTION_CONSTANT=1.
+=========+===========+=======+=======+=====+ +=========+===========+=======+=======+=====+
| Node | N | T_N_u | M_N_u | BAD | | Node | N | T_N_u | M_N_u | BAD |
+=========+===========+=======+=======+=====+ +=========+===========+=======+=======+=====+
| Leaf111 | Spine 111 | 110 | 7 | 2 | | Leaf111 | Spine 111 | 110 | 7 | 2 |
+---------+-----------+-------+-------+-----+ +---------+-----------+-------+-------+-----+
| Leaf111 | Spine 112 | 220 | 8 | 1 | | Leaf111 | Spine 112 | 220 | 8 | 1 |
+---------+-----------+-------+-------+-----+ +---------+-----------+-------+-------+-----+
| Leaf112 | Spine 111 | 120 | 7 | 2 | | Leaf112 | Spine 111 | 120 | 7 | 2 |
+---------+-----------+-------+-------+-----+ +---------+-----------+-------+-------+-----+
| Leaf112 | Spine 112 | 220 | 8 | 1 | | Leaf112 | Spine 112 | 220 | 8 | 1 |
+---------+-----------+-------+-------+-----+ +---------+-----------+-------+-------+-----+
Table 6: BAD Computation Table 6: BAD Computation
If a calculation produces a result exceeding the range of the type, If a calculation produces a result exceeding the range of the type,
e.g. bandwidth, the result is set to the highest possible value for e.g., bandwidth, the result is set to the highest possible value for
that type. that type.
BAD SHOULD only be computed for default routes. A node MAY compute BAD SHOULD only be computed for default routes. A node MAY compute
and use BAD for any disaggregated prefixes or other RIFT routes. A and use BAD for any disaggregated prefixes or other RIFT routes. A
node MAY use a different algorithm to weight northbound traffic based node MAY use a different algorithm to weight northbound traffic based
on bandwidth. If a different algorithm is used, its successful on the bandwidth. If a different algorithm is used, its successful
behavior MUST NOT depend on uniformity of algorithm or behavior MUST NOT depend on uniformity of the algorithm or
synchronization of BAD computations across the fabric. E.g. it is synchronization of BAD computations across the fabric. For example,
conceivable that leaves could use real time link loads gathered by it is conceivable that leaves could use real time link loads gathered
analytics to change the amount of traffic assigned to each default by analytics to change the amount of traffic assigned to each default
route next hop. route next hop.
A change in available bandwidth will only affect, at most, two levels A change in available bandwidth will only affect, at most, two levels
down in the fabric, i.e., the blast radius of bandwidth adjustments down in the fabric, i.e., the blast radius of bandwidth adjustments
is constrained no matter the fabric's height. is constrained no matter the fabric's height.
6.8.7.2. Southbound Direction 6.8.7.2. Southbound Direction
Due to its loop free nature, during South SPF, a node MAY account for Due to its loop-free nature, during South SPF, a node MAY account for
maximum available bandwidth on nodes in lower levels and modify the the maximum available bandwidth on nodes in lower levels and modify
amount of traffic offered to the next level's southbound nodes. It the amount of traffic offered to the next level's southbound nodes.
is worth considering that such computations may be more effective if It is worth considering that such computations may be more effective
standardized, but do not have to be. As long as a packet continues if they are standardized, but they do not have to be. As long as a
to flow southbound, it will take some viable, loop-free path to reach packet continues to flow southbound, it will take some viable, loop-
its destination. free path to reach its destination.
6.8.8. Label Binding 6.8.8. Label Binding
A node MAY advertise in its LIEs, a locally significant, downstream In its LIEs, a node MAY advertise a locally significant, downstream-
assigned, interface specific label. One use of such a label is a assigned, interface-specific label. One use of such a label is a
hop-by-hop encapsulation allowing forwarding planes to be easily hop-by-hop encapsulation allowing forwarding planes to be easily
distinguished among multiple RIFT instances. distinguished among multiple RIFT instances.
6.8.9. Leaf to Leaf Procedures 6.8.9. Leaf-to-Leaf Procedures
RIFT implementations SHOULD support special East-West adjacencies RIFT implementations SHOULD support special East-West adjacencies
between leaf nodes. Leaf nodes supporting these procedures MUST: between leaf nodes. Leaf nodes supporting these procedures MUST:
advertise the LEAF_2_LEAF flag in its node capabilities *and* 1. advertise the LEAF_2_LEAF flag in its node capabilities,
set the overload flag on all leaf's Node TIEs *and* 2. set the overload flag on all leaf's Node TIEs,
flood only a node's own north and south TIEs over E-W leaf 3. flood only a node's own North and South TIEs over E-W leaf
adjacencies *and* adjacencies,
always use E-W leaf adjacency in all SPF computations *and* 4. always use E-W leaf adjacency in all SPF computations,
install a discard route for any advertised aggregate routes in a 5. install a discard route for any advertised aggregate routes in a
leaf's TIE *and* leaf's TIE, *and*
never form southbound adjacencies. 6. never form southbound adjacencies.
This will allow the E-W leaf nodes to exchange traffic strictly for This will allow the E-W leaf nodes to exchange traffic strictly for
the prefixes advertised in each other's north prefix TIEs since the the prefixes advertised in each other's north prefix TIEs since the
southbound computation will find the reverse direction in the other southbound computation will find the reverse direction in the other
node's TIE and install its north prefixes. node's TIE and install its north prefixes.
6.8.10. Address Family and Multi Topology Considerations 6.8.10. Address Family and Multi-Topology Considerations
Multi-Topology (MT)[RFC5120] and Multi-Instance (MI)[RFC8202] Multi-Topology (MT) [RFC5120] and Multi-Instance (MI) [RFC8202]
concepts are used today in link-state routing protocols to support concepts are used today in link-state routing protocols to support
several domains on the same physical topology. RIFT supports this several domains on the same physical topology. RIFT supports this
capability by carrying transport ports in the LIE protocol exchanges. capability by carrying transport ports in the LIE protocol exchanges.
Multiplexing of LIEs can be achieved by either choosing varying Multiplexing of LIEs can be achieved by either choosing varying
multicast addresses or ports on the same address. multicast addresses or ports on the same address.
BFD interactions in Section 6.8.6 are implementation dependent when BFD interactions in Section 6.8.6 are implementation-dependent when
multiple RIFT instances run on the same link. multiple RIFT instances run on the same link.
6.8.11. One-Hop Healing of Levels with East-West Links 6.8.11. One-Hop Healing of Levels with East-West Links
Based on the rules defined in Section 6.4, Section 6.3.8 and given Based on the rules defined in Sections 6.4 and 6.3.8 and given the
the presence of E-W links, RIFT can provide a one-hop protection for presence of E-W links, RIFT can provide a one-hop protection for
nodes that have lost all their northbound links. This can also be nodes that have lost all their northbound links. This can also be
applied to multi-plane designs where complex link set failures occur applied to multi-plane designs where complex link set failures occur
at the ToF when links are exclusively used for flooding topology at the ToF when links are exclusively used for flooding topology
information. Appendix B.4 outlines this behavior. information. Appendix B.4 outlines this behavior.
6.9. Security 6.9. Security
6.9.1. Security Model 6.9.1. Security Model
An inherent property of any security and ZTP architecture is the An inherent property of any security and ZTP architecture is the
resulting trade-off in regard to integrity verification of the resulting trade-off in regard to integrity verification of the
information distributed through the fabric vs. provisioning and auto- information distributed through the fabric vs. provisioning and
configuration requirements. At a minimum the security of an autoconfiguration requirements. At a minimum, the security of an
established adjacency should be ensured. The stricter the security established adjacency should be ensured. The stricter the security
model the more provisioning must take over the role of ZTP. model, the more provisioning must take over the role of ZTP.
RIFT supports the following security models to allow for flexible RIFT supports the following security models to allow for flexible
control by the operator. control by the operator:
* The most security conscious operators may choose to have control * The most security-conscious operators may choose to have control
over which ports interconnect between a given pair of nodes, such over which ports interconnect between a given pair of nodes, such
a model is called the "Port-Association Model" (PAM). This is a model is called the "Port-Association Model" (PAM). This is
achievable by configuring each pair of directly connected ports achievable by configuring each pair of directly connected ports
with a designated shared key or public/private key pair. with a designated shared key or public/private key pair.
* In physically secure data center locations, operators may choose * In physically secure data center locations, operators may choose
to control connectivity between entire nodes, called here the to control connectivity between entire nodes, called here the
"Node-Association Model" (NAM). A benefit of this model is that "Node-Association Model" (NAM). A benefit of this model is that
it allows for simplified port sparing. it allows for simplified port sparing.
skipping to change at page 118, line 20 skipping to change at line 5269
are replaced more often than network nodes. In addition, this are replaced more often than network nodes. In addition, this
model allows for simplified node sparing. model allows for simplified node sparing.
* These models may be mixed throughout the fabric depending upon * These models may be mixed throughout the fabric depending upon
security requirements at various levels of the fabric and security requirements at various levels of the fabric and
willingness to accept increased provisioning complexity. willingness to accept increased provisioning complexity.
In order to support the cases mentioned above, RIFT implementations In order to support the cases mentioned above, RIFT implementations
supports, through operator control, mechanisms that allow for: supports, through operator control, mechanisms that allow for:
a. specification of the appropriate level in the fabric, * a specification of the appropriate level in the fabric,
b. discovery and reporting of missing connections, * discovery and reporting of missing connections, and
c. discovery and reporting of unexpected connections while * discovery and reporting of unexpected connections while preventing
preventing them from forming insecure adjacencies. them from forming insecure adjacencies.
Operators may only choose to configure the level of each node, but Operators may only choose to configure the level of each node but not
not explicitly configure which connections are allowed. In this explicitly configure which connections are allowed. In this case,
case, RIFT will only allow adjacencies to establish between nodes RIFT will only allow adjacencies to establish between nodes that are
that are in adjacent levels. Operators with the lowest security in adjacent levels. Operators with the lowest security requirements
requirements may not use any configuration to specify which may not use any configuration to specify which connections are
connections are allowed. Nodes in such fabrics could rely fully on allowed. Nodes in such fabrics could rely fully on ZTP and
ZTP and only established adjacencies between nodes in adjacent established adjacencies between nodes in adjacent levels. Figure 33
levels. Figure 33 illustrates inherent tradeoffs between the illustrates inherent trade-offs between the different security
different security models. models.
Some level of link quality verification may be required prior to an Some level of link quality verification may be required prior to an
adjacency being used for forwarding. For example, an implementation adjacency being used for forwarding. For example, an implementation
may require that a BFD session comes up before advertising the may require that a BFD session comes up before advertising the
adjacency. adjacency.
For the cases outlined above, RIFT has two approaches to enforce that For the cases outlined above, RIFT has two approaches to enforce that
a local port is connected to the correct port on the correct remote a local port is connected to the correct port on the correct remote
node. One approach is to piggy-back on RIFT's authentication node. One approach is to piggyback on RIFT's authentication
mechanism. Assuming the provisioning model (e.g. YANG) is flexible mechanism. Assuming the provisioning model (e.g., YANG) is flexible
enough, operators can choose to provision a unique authentication key enough, operators can choose to provision a unique authentication key
for the following conceptual models: for the following conceptual models:
a. each pair of ports in "port-association model" or * each pair of ports in "port-association model"
b. each pair of switches in "node-association model" or * each pair of switches in "node-association model", or
c. the entire fabric in "fabric-association model".
The other approach is to rely on the System ID, port-id and level * the entire fabric in "fabric-association model".
The other approach is to rely on the System ID, port-id, and level
fields in the LIE message to validate an adjacency against the fields in the LIE message to validate an adjacency against the
expected cabling topology, and optionally introduce some new rules in expected cabling topology and optionally introduce some new rules in
the FSM to allow the adjacency to come up if the expectations are the FSM to allow the adjacency to come up if the expectations are
met. met.
^ /\ | ^ /\ |
/|\ / \ | /|\ / \ |
| / \ | | / \ |
| / PAM \ | | / PAM \ |
Increasing / \ Increasing Increasing / \ Increasing
Integrity +----------+ Flexibility Integrity +----------+ Flexibility
& / NAM \ & & / NAM \ &
skipping to change at page 119, line 30 skipping to change at line 5328
Provisioning / FAM \ Configuration Provisioning / FAM \ Configuration
| / \ | | / \ |
| +--------------------+ \|/ | +--------------------+ \|/
| / Zero Configuration \ v | / Zero Configuration \ v
+------------------------+ +------------------------+
Figure 33: Security Model Figure 33: Security Model
6.9.2. Security Mechanisms 6.9.2. Security Mechanisms
RIFT Security goals are to ensure: RIFT security goals are to ensure:
1. authentication * authentication,
2. message integrity * message integrity,
3. the prevention of replay attacks * the prevention of replay attacks,
4. low processing overhead * low processing overhead, and
5. efficient messaging * efficient messaging
unless no security is deployed by means of using unless no security is deployed by means of using
`undefined_securitykey_id` as key identifiers. 'undefined_securitykey_id' as key identifiers.
Message confidentiality is a non-goal. Message confidentiality is a non-goal.
The model in the previous section allows a range of security key The model in the previous section allows a range of security key
types that are analogous to the various security association models. types that are analogous to the various security association models.
PAM and NAM allow security associations at the port or node level PAM and NAM allow security associations at the port or node level
using symmetric or asymmetric keys that are pre-installed. FAM using symmetric or asymmetric keys that are preinstalled. FAM argues
argues for security associations to be applied only at a group level for security associations to be applied only at a group level or to
or to be refined once the topology has been established. RIFT does be refined once the topology has been established. RIFT does not
not specify how security keys are installed or updated, though it specify how security keys are installed or updated, though it does
does specify how the key can be used to achieve security goals. specify how the key can be used to achieve security goals.
The protocol has provisions for "weak" nonces to prevent replay The protocol has provisions for "weak" nonces to prevent replay
attacks and includes authentication mechanisms comparable to attacks and includes authentication mechanisms comparable to those
[RFC5709] and [RFC7987]. described in [RFC5709] and [RFC7987].
6.9.3. Security Envelope 6.9.3. Security Envelope
A serialized schema _ProtocolPacket_ MUST be carried in a secure A serialized schema _ProtocolPacket_ MUST be carried in a secure
envelope illustrated in Figure 34. The _ProtocolPacket_ MUST be envelope as illustrated in Figure 34. The _ProtocolPacket_ MUST be
serialized using the default Thrift's Binary Protocol. Any value in serialized using the default Thrift's binary protocol. Any value in
the packet following a security fingerprint MUST be used by a the packet following a security fingerprint MUST be used by a
receiver only after the fingerprint generated based on acceptable, receiver only after the fingerprint generated based on acceptable,
advertised key ID has been validated against the data covered by it advertised key ID has been validated against the data covered by it
bare exceptions arising from operational exigencies where, based on bare exceptions arising from operational exigencies where, based on
local configuration, a node MAY allow for the envelope's integrity local configuration, a node MAY allow for the envelope's integrity
checks to be skipped and for behavior specified in Section 6.9.6. checks to be skipped and for behavior specified in Section 6.9.6.
This means that for all packets, in case the node is configured to This means that for all packets, in case the node is configured to
validate the outer fingerprint based on a key ID, an unexpected key validate the outer fingerprint based on a key ID, an unexpected key
ID or fingerprint not validating against expected key ID will lead to ID or fingerprint not validating against the expected key ID will
packet rejection. Further, in case of reception of a TIE, and the lead to packet rejection. Further, in case of reception of a TIE and
receiver being configured to validate the originator by checking the the receiver being configured to validate the originator by checking
TIE Origin Security Envelope Header fingerprint against a key ID, an the TIE Origin Security Envelope Header fingerprint against a key ID,
incorrect key ID or inner fingerprint not validating against the key an incorrect key ID or inner fingerprint not validating against the
ID will lead to the rejection of the packet. key ID will lead to the rejection of the packet.
For reasons of clarity it is important to observe that the For reasons of clarity, it is important to observe that the
specification uses the word fingerprint and signature interchangeably specification uses the words "fingerprint" and "signature"
since the specific properties of the fingerprint part of the envelope interchangeably since the specific properties of the fingerprint part
depend on the algorithms used to insure the payload integrity. of the envelope depend on the algorithms used to insure the payload
Moreover, any security chosen never implies encryption due to integrity. Moreover, any security chosen never implies encryption
performance impact involved but only fingerprint or signature due to performance impact involved but only fingerprint or signature
generation and validation. generation and validation.
An implementation MUST implement at least both sending and receiving An implementation MUST implement at least both sending and receiving
HMAC-SHA256 fingerprints as defined in Section 10.2 to ensure HMAC-SHA256 fingerprints as defined in Section 10.2 to ensure
interoperability but MAY use `undefined_securitykey_id` by default. interoperability but MAY use 'undefined_securitykey_id' by default.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
UDP Header: UDP Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | RIFT destination port | | Source Port | RIFT destination port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP Length | UDP Checksum | | UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Outer Security Envelope Header: Outer Security Envelope Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RIFT MAGIC | Packet Number | | RIFT MAGIC | Packet Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | RIFT Major | Outer Key ID | Fingerprint | | Reserved | RIFT Major | Outer Key ID | Fingerprint |
| | Version | | Length | | | Version | | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ Security Fingerprint covers all following content ~ ~ Security Fingerprint covers all following content ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weak Nonce Local | Weak Nonce Remote | | Weak Nonce Local | Weak Nonce Remote |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remaining TIE Lifetime (all 1s in case of LIE) | | Remaining TIE Lifetime (all 1s in case of LIE) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TIE Origin Security Envelope Header: TIE Origin Security Envelope Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TIE Origin Key ID | Fingerprint | | TIE Origin Key ID | Fingerprint |
| | Length | | | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ Security Fingerprint covers all following content ~ ~ Security Fingerprint covers all following content ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Serialized RIFT Model Object Serialized RIFT Model Object
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ Serialized RIFT Model Object ~ ~ Serialized RIFT Model Object ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 34: Security Envelope Figure 34: Security Envelope
RIFT MAGIC: RIFT MAGIC: 16 bits
16 bits. Constant value of 0xA1F7 that allows easy classification
of RIFT packets independent of the UDP port used.
Packet Number: Constant value of 0xA1F7 that allows easy classification of RIFT
16 bits. An optional, per adjacency, per packet type number set packets independent of the UDP port used.
using the sequence number arithmetic defined in Appendix A. If
the arithmetic in Appendix A is not used the node MUST set the Packet Number: 16 bits
value to _undefined_packet_number_. This number can be used to
detect losses and misordering in flooding for either operational An optional, per-adjacency, per-packet type number set using the
purposes or in implementation to adjust flooding behavior to sequence number arithmetic defined in Appendix A. If the
current link or buffer quality. This number MUST NOT be used to arithmetic in Appendix A is not used, the node MUST set the value
discard or validate the correctness of packets. Packet numbers to _undefined_packet_number_. This number can be used to detect
are incremented on each interface and within that for each type of losses and misordering in flooding for either operational purposes
or in implementation to adjust flooding behavior to current link
or buffer quality. This number MUST NOT be used to discard or
validate the correctness of packets. Packet numbers are
incremented on each interface and within that for each type of
packet independently. This allows parallelizing packet generation packet independently. This allows parallelizing packet generation
and processing for different types within an implementation if so and processing for different types within an implementation, if so
desired. desired.
RIFT Major Version: RIFT Major Version: 8 bits
8 bits. This value MUST be set to `protocol_major_version`
This value MUST be set to "protocol_major_version", which is
defined in the schema and used to serialize the object contained. defined in the schema and used to serialize the object contained.
It allows checking whether protocol versions are compatible on It allows checking whether protocol versions are compatible on
both sides, i.e., which schema version is necessary to decode the both sides, i.e., which schema version is necessary to decode the
serialized object. An implementation MUST drop packets with serialized object. An implementation MUST drop packets with
unexpected values and MAY report a problem. The specification of unexpected values and MAY report a problem. The specification of
how an implementation may negotiate the schema's major version is how an implementation may negotiate the schema's major version is
outside the scope of this document. outside the scope of this document.
Outer Key ID: Outer Key ID: 8 bits
8 bits. A simple, unstructured value acting as indirection into a
A simple, unstructured value acting as indirection into a
structure holding an algorithm and any related secrets necessary structure holding an algorithm and any related secrets necessary
to validate any provided outer security fingerprint or signature. to validate any provided outer security fingerprint or signature.
Value _undefined_securitykey_id_ means that no valid fingerprint The value _undefined_securitykey_id_ means that no valid
was computed or is provided, otherwise one of the algorithms in fingerprint was computed or is provided; otherwise, one of the
Section 10.2 MUST be used to compute the fingerprint. This Key ID algorithms in Section 10.2 MUST be used to compute the
scope is local to the nodes on both ends of the adjacency. fingerprint. This key ID scope is local to the nodes on both ends
of the adjacency.
TIE Origin Key ID: TIE Origin Key ID: 24 bits
24 bits. A simple, unstructured value acting as indirection into
a structure holding an algorithm and any related secrets necessary A simple, unstructured value acting as indirection into a
structure holding an algorithm and any related secrets necessary
to validate any provided inner security fingerprint or signature. to validate any provided inner security fingerprint or signature.
Value _undefined_securitykey_id_ means that no valid fingerprint The value _undefined_securitykey_id_ means that no valid
was computed, otherwise one of the algorithms in Section 10.2 MUST fingerprint was computed; otherwise, one of the algorithms in
be used to compute the fingerprint.. This Key ID scope is global Section 10.2 MUST be used to compute the fingerprint. This key ID
to the RIFT instance since it may imply the originator of the TIE scope is global to the RIFT instance since it may imply the
so the contained object does not have to be de-serialized to originator of the TIE so the contained object does not have to be
obtain the originator. deserialized to obtain the originator.
Length of Fingerprint: Fingerprint Length: 8 bits
8 bits. Length in 32-bit multiples of the following fingerprint
(not including lifetime or weak nonces). It allows the structure Length in 32-bit multiples of the following fingerprint (not
to be navigated when an unknown key type is present. To clarify, including lifetime or weak nonces). It allows the structure to be
a common corner case when this value is set to 0 is when it navigated when an unknown key type is present. To clarify, a
common corner case when this value is set to 0 is when it
signifies an empty (0 bytes long) security fingerprint. signifies an empty (0 bytes long) security fingerprint.
Security Fingerprint: Security Fingerprint: 32 bits * Fingerprint Length.
32 bits * Length of Fingerprint. This is a signature that is
computed over all data following after it. If the significant
bits of fingerprint are fewer than the 32 bits padded length then
the significant bits MUST be left aligned and remaining bits on
the right padded with 0s. When using PKI (Public Key
Infrastructure) the Security fingerprint originating node uses its
private key to create the signature. The original packet can then
be verified provided the public key is shared and current.
Methodology to negotiate, distribute, or roll over keys are
outside the scope of this document.
Remaining TIE Lifetime: This is a signature that is computed over all data following after
32 bits. In case of anything but TIEs this field MUST be set to it. If the significant bits of the fingerprint are fewer than the
all ones and Origin Security Envelope Header MUST NOT be present 32-bit padded length, then the significant bits MUST be left
in the packet. For TIEs this field represents the remaining aligned and the remaining bits on the right are padded with 0s.
lifetime of the TIE and Origin Security Envelope Header MUST be When using Public Key Infrastructure (PKI), the security
present in the packet. fingerprint originating node uses its private key to create the
signature. The original packet can then be verified, provided the
public key is shared and current. Methodology to negotiate,
distribute, or rollover keys is outside the scope of this
document.
Weak Nonce Local: Remaining TIE Lifetime: 32 bits
16 bits. Local Weak Nonce of the adjacency as advertised in LIEs.
Weak Nonce Remote: In case of anything but TIEs, this field MUST be set to all ones
16 bits. Remote Weak Nonce of the adjacency as received in LIEs. and the Origin Security Envelope Header MUST NOT be present in the
packet. For TIEs, this field represents the remaining lifetime of
the TIE and the Origin Security Envelope Header MUST be present in
the packet.
TIE Origin Security Envelope Header: Weak Nonce Local: 16 bits
It MUST be present if and only if the Remaining TIE Lifetime field
is *not* all ones. It carries through the originators Key ID and
corresponding fingerprint of the object to protect TIE from
modification during flooding. This ensures origin validation and
integrity (but does not provide validation of a chain of trust).
Observe that due to the schema migration rules per Section 7 the Local Weak Nonce of the adjacency, as advertised in LIEs.
contained model can be always decoded if the major version matches
Weak Nonce Remote: 16 bits
Remote Weak Nonce of the adjacency, as received in LIEs.
TIE Origin Security Envelope Header: It MUST be present if and only
if the Remaining TIE Lifetime field is *not* all ones. It carries
through the originator's key ID and corresponding fingerprint of
the object to protect TIE from modification during flooding. This
ensures origin validation and integrity (but does not provide
validation of a chain of trust).
Observe that, due to the schema migration rules per Section 7, the
contained model can always be decoded if the major version matches
and the envelope integrity has been validated. Consequently, and the envelope integrity has been validated. Consequently,
description of the TIE is available to flood it properly including description of the TIE is available to flood it properly, including
unknown TIE types. unknown TIE types.
6.9.4. Weak Nonces 6.9.4. Weak Nonces
The protocol uses two 16-bit nonces to salt generated signatures. The protocol uses two 16-bit nonces to salt generated signatures.
The term "nonce" is used a bit loosely since RIFT nonces are not The term "nonce" is used a bit loosely since RIFT nonces are not
being changed in every packet as often common in cryptography. For being changed in every packet, which is common in cryptography. For
efficiency purposes they are changed at a high enough frequency to efficiency purposes, they are changed at a high enough frequency to
dwarf practical replay attack attempts. And hence, such nonces are dwarf practical replay attack attempts. And hence, such nonces are
called from this point on "weak" nonces. called from this point on "weak" nonces.
Any implementation using outer key ID different from Any implementation using a different outer key ID from
`undefined_securitykey_id` MUST generate and wrap around local nonces 'undefined_securitykey_id' MUST generate and wrap around local nonces
properly and SHOULD do it even if not using any algorithm in properly and SHOULD do it even if not using any algorithm from
Section 10.2. When a nonce increment leads to _undefined_nonce_ Section 10.2. When a nonce increment leads to the _undefined_nonce_
value, the value MUST be incremented again immediately. All value, the value MUST be incremented again immediately. All
implementations MUST reflect the neighbor's nonces. An implementations MUST reflect the neighbor's nonces. An
implementation SHOULD increment a chosen nonce on every LIE FSM implementation SHOULD increment a chosen nonce on every LIE FSM
transition that ends up in a different state from the previous one transition that ends up in a different state from the previous one
and MUST increment its nonce at least every and MUST increment its nonce at least every
_nonce_regeneration_interval_ if using any algorithm in Section 10.2 _nonce_regeneration_interval_ if using any algorithm in Section 10.2
(such considerations allow for efficient implementations without (such considerations allow for efficient implementations without
opening a significant security risk). When flooding TIEs, the opening a significant security risk). When flooding TIEs, the
implementation MUST use recent (i.e. within allowed difference) implementation MUST use recent (i.e., within allowed difference)
nonces reflected in the LIE exchange. The schema specifies in nonces reflected in the LIE exchange. The schema specifies in
_maximum_valid_nonce_delta_ the maximum allowable nonce value _maximum_valid_nonce_delta_ the maximum allowable nonce value
difference on a packet compared to reflected nonces in the LIEs. Any difference on a packet compared to reflected nonces in the LIEs. Any
packet received with nonces deviating more than the allowed delta packet received with nonces deviating more than the allowed delta
MUST be discarded without further computation of signatures to MUST be discarded without further computation of signatures to
prevent computation load attacks. The delta is either a negative or prevent computation load attacks. The delta is either a negative or
positive difference that a mirrored nonce can deviate from local positive difference that a mirrored nonce can deviate from the local
value to be considered valid. If nonces are not changed on every value to be considered valid. If nonces are not changed on every
packet but at the maximum interval on both sides this opens packet, but at the maximum interval on both sides, this opens
statistically a _maximum_valid_nonce_delta_/2 window for identical statistically a _maximum_valid_nonce_delta_/2 window for identical
LIEs, TIE and TI(x)E replays. The interval cannot be too small since LIEs, TIE, and TI(x)E replays. The interval cannot be too small
LIE FSM may change states fairly quickly during ZTP without sending since LIE FSM may change states fairly quickly during ZTP without
LIEs and additionally, UDP can both loose as well as misorder sending LIEs, and additionally, UDP can both loose as well as
packets. misorder packets.
In cases where a secure implementation does not receive signatures or In cases where a secure implementation does not receive signatures or
receives undefined nonces from a neighbor (indicating that it does receives undefined nonces from a neighbor (indicating that it does
not support or verify signatures), it is a matter of local policy as not support or verify signatures), it is a matter of local policy as
to how those packets are treated. A secure implementation MAY refuse to how those packets are treated. A secure implementation MAY refuse
forming an adjacency with an implementation that is not advertising forming an adjacency with an implementation that is not advertising
signatures or valid nonces, or it MAY continue signing local packets signatures or valid nonces, or it MAY continue signing local packets
while accepting a neighbor's packets without further security while accepting a neighbor's packets without further security
validation. validation.
As a necessary exception, an implementation MUST advertise the remote As a necessary exception, an implementation MUST advertise the remote
nonce value as _undefined_nonce_ when the FSM is not in _TwoWay_ or nonce value as _undefined_nonce_ when the FSM is not in _TwoWay_ or
_ThreeWay_ state and accept an _undefined_nonce_ for its local nonce _ThreeWay_ state and accept an _undefined_nonce_ for its local nonce
value on packets in any other state than _ThreeWay_. value on packets in any other state than _ThreeWay_.
As an optional optimization, an implementation MAY send one LIE with As an optional optimization, an implementation MAY send one LIE with
previously negotiated neighbor's nonce to try to speed up a a previously negotiated neighbor's nonce to try to speed up a
neighbor's transition from _ThreeWay_ to _OneWay_ and MUST revert to neighbor's transition from _ThreeWay_ to _OneWay_ and MUST revert to
sending _undefined_nonce_ after that. sending _undefined_nonce_ after that.
6.9.5. Lifetime 6.9.5. Lifetime
Reflooding same TIE version quickly with small variations in its Reflooding the same TIE version quickly with small variations in its
lifetime may lead to an excessive number of security fingerprint lifetime may lead to an excessive number of security fingerprint
computations. To avoid this, the application generating the computations. To avoid this, the application generating the
fingerprints for flooded TIEs MAY round the value down to the next fingerprints for flooded TIEs MAY round the value down to the next
_rounddown_lifetime_interval_ on the packet header to reuse previous _rounddown_lifetime_interval_ on the packet header to reuse previous
computation results. TIEs flooded with such rounded lifetimes only computation results. TIEs flooded with such rounded lifetimes will
will limit the amount of computations necessary during transitions only limit the amount of computations necessary during transitions
that lead to advertisement of same TIEs with same information within that lead to advertisement of the same TIEs with the same information
a short period of time. within a short period of time.
6.9.6. Security Association Changes 6.9.6. Security Association Changes
No mechanism is specified to convert a security envelope for the same No mechanism is specified to convert a security envelope for the same
Key ID from one algorithm to another once the envelope is key ID from one algorithm to another once the envelope is
operational. The recommended procedure to change to a new algorithm operational. The recommended procedure to change to a new algorithm
is to take the adjacency down, make the necessary changes to the is to take the adjacency down, make the necessary changes to the
secret and algorithm used by the according key ID, and bring the secret and algorithm used by the according key ID, and bring the
adjacency back up. Obviously, an implementation MAY choose to stop adjacency back up. Obviously, an implementation MAY choose to stop
verifying security envelope for the duration of algorithm change to verifying the security envelope for the duration of the algorithm
keep the adjacency up but since this introduces a security change to keep the adjacency up, but since this introduces a security
vulnerability window, such roll-over SHOULD NOT be recommended. vulnerability window, such rollover SHOULD NOT be recommended. Other
Other approaches, such as accepting multiple algorithms for same key approaches, such as accepting multiple algorithms for same key ID for
ID for a configured time window are possible but in the realm of a configured time window, are possible but in the realm of
implementation choices rather than protocol specification. implementation choices rather than protocol specification.
7. Information Elements Schema 7. Information Elements Schema
This section introduces the schema for information elements. The IDL This section introduces the schema for information elements. The IDL
is Thrift [thrift]. is Thrift [thrift].
On schema changes that On schema changes that
1. change field numbers *or* 1. change field numbers,
2. add new *required* fields *or* 2. add new *required* fields,
3. remove any fields *or*
4. change lists into sets, unions into structures *or* 3. remove any fields.
5. change multiplicity of fields *or* 4. change lists into sets and unions into structures,
6. changes type or name of any field *or* 5. change the multiplicity of fields,
7. change data types of the type of any field *or* 6. change the type or name of any field,
8. adds, changes or removes a default value of any *existing* field 7. change data types of the type of any field,
*or*
9. removes or changes any defined constant or constant value *or* 8. add, change, or remove a default value of any *existing* field,
10. changes any enumeration type except extending 9. remove or change any defined constant or constant value,
`common.TIETypeType` (use of enumeration types is generally
discouraged) *or*
11. adds new TIE type to _TIETypeType_ with flooding scope different 10. change any enumeration type except extending
from prefix TIE flooding scope 'common.TIETypeType' (use of enumeration types is generally
discouraged), or
major version of the schema MUST increase. All other changes MUST 11. add a new TIE type to _TIETypeType_ with the flooding scope
increase minor version within the same major. different from the prefix TIE flooding scope
the major version of the schema MUST increase. All other changes
MUST increase the minor version within the same major.
Introducing an optional field does not cause a major version increase Introducing an optional field does not cause a major version increase
even if the fields inside the structure are optional with defaults. even if the fields inside the structure are optional with defaults.
All signed integer as forced by Thrift [thrift] support must be cast All signed integers, as forced by Thrift [thrift] support, must be
for internal purposes to equivalent unsigned values without cast for internal purposes to equivalent unsigned values without
discarding the signedness bit. An implementation SHOULD try to avoid discarding the signedness bit. An implementation SHOULD try to avoid
using the signedness bit when generating values. using the signedness bit when generating values.
The schema is normative. The schema is normative.
7.1. Backwards-Compatible Extension of Schema 7.1. Backwards-Compatible Extension of Schema
The set of rules in Section 7 guarantees that every decoder can The set of rules in Section 7 guarantees that every decoder can
process serialized content generated by a higher minor version of the process serialized content generated by a higher minor version of the
schema and with that the protocol can progress without a 'flag-day'. schema, and with that, the protocol can progress without a 'flag-
Contrary to that, content serialized using a major version X is *not* day'. Contrary to that, content serialized using a major version X
expected to be decodable by any implementation using decoder for a is *not* expected to be decodable by any implementation using a
model with a major version lower than X. Schema negotiation and decoder for a model with a major version lower than X. Schema
translation within RIFT is outside the scope of this document. negotiation and translation within RIFT is outside the scope of this
document.
Additionally, based on the propagated minor version in encoded Additionally, based on the propagated minor version in encoded
content and added optional node capabilities new TIE types or even content and added optional node capabilities, new TIE types or even
de-facto mandatory fields can be introduced without progressing the de facto mandatory fields can be introduced without progressing the
major version albeit only nodes supporting such new extensions would major version, albeit only nodes supporting such new extensions would
decode them. Given the model is encoded at the source and never re- decode them. Given the model is encoded at the source and never re-
encoded flooding through nodes not understanding any new extensions encoded, flooding through nodes not understanding any new extensions
will preserve the corresponding fields. However, it is important to will preserve the corresponding fields. However, it is important to
understand that a higher minor version of a schema does *not* understand that a higher minor version of a schema does *not*
guarantee that capabilities introduced in lower minors of the same guarantee that capabilities introduced in lower minors of the same
major are supported. The _node_capabilities_ field is used to major are supported. The _node_capabilities_ field is used to
indicate which capabilities are supported. indicate which capabilities are supported.
Specifically, the schema SHOULD add elements to _NodeCapabilities_ Specifically, the schema SHOULD add elements to the
field future capabilities to indicate whether it will support _NodeCapabilities_ field's future capabilities to indicate whether it
interpretation of schema extensions on the same major revision if will support interpretation of schema extensions on the same major
they are present. Such fields MUST be optional and have an implicit revision if they are present. Such fields MUST be optional and have
or explicit false default value. If a future capability changes an implicit or explicit false default value. If a future capability
route selection or generates conditions that cause packet loss if changes route selection or generates conditions that cause packet
some nodes are not supporting it then a major version increment will loss if some nodes are not supporting it, then a major version
be however unavoidable. _NodeCapabilities_ shown in LIE MUST match increment will be unavoidable. _NodeCapabilities_ shown in LIE MUST
the capabilities shown in the Node TIEs, otherwise the behavior is match the capabilities shown in the Node TIEs; otherwise, the
unspecified. A node detecting the mismatch SHOULD generate a behavior is unspecified. A node detecting the mismatch SHOULD
notification. generate a notification.
Alternately or additionally, new optional fields can be introduced Alternately or additionally, new optional fields can be introduced
into e.g. _NodeTIEElement_ if a special field is chosen to indicate into, e.g., _NodeTIEElement_, if a special field is chosen to
via its presence that an optional feature is enabled (since indicate via its presence that an optional feature is enabled (since
capability to support a feature does not necessarily mean that the capability to support a feature does not necessarily mean that the
feature is actually configured and operational). feature is actually configured and operational).
To support new TIE types without increasing the major version To support new TIE types without increasing the major version
enumeration _TIEElement_ can be extended with new optional elements enumeration, _TIEElement_ can be extended with new optional elements
for new `common.TIETypeType` values as long the scope of the new TIE for new 'common.TIETypeType' values as long the scope of the new TIE
matches the prefix TIE scope. In case it is necessary to understand matches the prefix TIE scope. In case it is necessary to understand
whether all nodes can parse the new TIE type a node capability MUST whether all nodes can parse the new TIE type, a node capability MUST
be added in _NodeCapabilities_ to prevent a non-homogenous network. be added in _NodeCapabilities_ to prevent a non-homogenous network.
7.2. common.thrift 7.2. common.thrift
/** /**
Thrift file with common definitions for RIFT Thrift file with common definitions for RIFT
*/ */
namespace py common namespace py common
/** @note MUST be interpreted in implementation as unsigned 64 bits. /** @note MUST be interpreted in implementation as unsigned 64 bits.
*/ */
typedef i64 SystemIDType typedef i64 SystemIDType
typedef i32 IPv4Address typedef i32 IPv4Address
typedef i32 MTUSizeType typedef i32 MTUSizeType
/** @note MUST be interpreted in implementation as unsigned /** @note MUST be interpreted in implementation as unsigned
rolling over number */ rolling over number */
typedef i64 SeqNrType typedef i64 SeqNrType
/** @note MUST be interpreted in implementation as unsigned */ /** @note MUST be interpreted in implementation as unsigned */
typedef i32 LifeTimeInSecType typedef i32 LifeTimeInSecType
/** @note MUST be interpreted in implementation as unsigned */ /** @note MUST be interpreted in implementation as unsigned */
typedef i8 LevelType typedef i8 LevelType
typedef i16 PacketNumberType typedef i16 PacketNumberType
/** @note MUST be interpreted in implementation as unsigned */ /** @note MUST be interpreted in implementation as unsigned */
typedef i32 PodType typedef i32 PodType
/** @note MUST be interpreted in implementation as unsigned. /** @note MUST be interpreted in implementation as unsigned.
/** this has to be long enough to accomodate prefix */ /** this has to be long enough to accommodate prefix */
typedef binary IPv6Address typedef binary IPv6Address
/** @note MUST be interpreted in implementation as unsigned */ /** @note MUST be interpreted in implementation as unsigned */
typedef i16 UDPPortType typedef i16 UDPPortType
/** @note MUST be interpreted in implementation as unsigned */ /** @note MUST be interpreted in implementation as unsigned */
typedef i32 TIENrType typedef i32 TIENrType
/** @note MUST be interpreted in implementation as unsigned /** @note MUST be interpreted in implementation as unsigned
This is carried in the This is carried in the security envelope and must
security envelope and must hence fit into 8 bits. */ hence fit into 8 bits. */
typedef i8 VersionType typedef i8 VersionType
/** @note MUST be interpreted in implementation as unsigned */ /** @note MUST be interpreted in implementation as unsigned */
typedef i16 MinorVersionType typedef i16 MinorVersionType
/** @note MUST be interpreted in implementation as unsigned */ /** @note MUST be interpreted in implementation as unsigned */
typedef i32 MetricType typedef i32 MetricType
/** @note MUST be interpreted in implementation as unsigned /** @note MUST be interpreted in implementation as unsigned
and unstructured */ and unstructured */
typedef i64 RouteTagType typedef i64 RouteTagType
/** @note MUST be interpreted in implementation as unstructured /** @note MUST be interpreted in implementation as unstructured
label value */ label value */
typedef i32 LabelType typedef i32 LabelType
/** @note MUST be interpreted in implementation as unsigned */ /** @note MUST be interpreted in implementation as unsigned */
typedef i32 BandwithInMegaBitsType typedef i32 BandwidthInMegaBitsType
/** @note Key Value Key ID type */ /** @note Key Value key ID type */
typedef i32 KeyIDType typedef i32 KeyIDType
/** node local, unique identification for a link (interface/tunnel /** node local, unique identification for a link (interface/tunnel/
* etc. Basically anything RIFT runs on). This is kept * etc., basically anything RIFT runs on). This is kept
* at 32 bits so it aligns with BFD [RFC5880] discriminator size. * at 32 bits so it aligns with BFD (RFC 5880) discriminator size.
*/ */
typedef i32 LinkIDType typedef i32 LinkIDType
/** @note MUST be interpreted in implementation as unsigned, /** @note MUST be interpreted in implementation as unsigned,
especially since we have the /128 IPv6 case. */ especially since we have the /128 IPv6 case. */
typedef i8 PrefixLenType typedef i8 PrefixLenType
/** timestamp in seconds since the epoch */ /** timestamp in seconds since the epoch */
typedef i64 TimestampInSecsType typedef i64 TimestampInSecsType
/** security nonce. /** security nonce.
@note MUST be interpreted in implementation as rolling @note MUST be interpreted in implementation as rolling
over unsigned value */ over unsigned value */
typedef i16 NonceType typedef i16 NonceType
/** LIE FSM holdtime type */ /** LIE FSM holdtime type */
typedef i16 TimeIntervalInSecType typedef i16 TimeIntervalInSecType
/** Transaction ID type for prefix mobility as specified by RFC6550, /** Transaction ID type for prefix mobility as specified by RFC 6550,
value MUST be interpreted in implementation as unsigned */ value MUST be interpreted in implementation as unsigned */
typedef i8 PrefixTransactionIDType typedef i8 PrefixTransactionIDType
/** Timestamp per IEEE 802.1AS, all values MUST be interpreted in /** Timestamp per IEEE 802.1AS, all values MUST be interpreted in
implementation as unsigned. */ implementation as unsigned. */
struct IEEE802_1ASTimeStampType { struct IEEE802_1ASTimeStampType {
1: required i64 AS_sec; 1: required i64 AS_sec;
2: optional i32 AS_nsec; 2: optional i32 AS_nsec;
} }
/** generic counter type */ /** generic counter type */
typedef i64 CounterType typedef i64 CounterType
/** Platform Interface Index type, i.e. index of interface on hardware, /** Platform Interface Index type, i.e., index of interface on hardware,
can be used e.g. with RFC5837 */ can be used, e.g., with RFC 5837 */
typedef i32 PlatformInterfaceIndex typedef i32 PlatformInterfaceIndex
/** Flags indicating node configuration in case of ZTP. /** Flags indicating node configuration in case of ZTP.
*/ */
enum HierarchyIndications { enum HierarchyIndications {
/** forces level to `leaf_level` and enables according procedures */ /** forces level to 'leaf_level' and enables according procedures */
leaf_only = 0, leaf_only = 0,
/** forces level to `leaf_level` and enables according procedures */ /** forces level to 'leaf_level' and enables according procedures */
leaf_only_and_leaf_2_leaf_procedures = 1, leaf_only_and_leaf_2_leaf_procedures = 1,
/** forces level to `top_of_fabric` and enables according /** forces level to 'top_of_fabric' and enables according
procedures */ procedures */
top_of_fabric = 2, top_of_fabric = 2,
} }
const PacketNumberType undefined_packet_number = 0 const PacketNumberType undefined_packet_number = 0
/** used when node is configured as top of fabric in ZTP.*/ /** used when node is configured as top of fabric in ZTP.*/
const LevelType top_of_fabric_level = 24 const LevelType top_of_fabric_level = 24
/** default bandwidth on a link */ /** default bandwidth on a link */
const BandwithInMegaBitsType default_bandwidth = 100 const BandwidthInMegaBitsType default_bandwidth = 100
/** fixed leaf level when ZTP is not used */ /** fixed leaf level when ZTP is not used */
const LevelType leaf_level = 0 const LevelType leaf_level = 0
const LevelType default_level = leaf_level const LevelType default_level = leaf_level
const PodType default_pod = 0 const PodType default_pod = 0
const LinkIDType undefined_linkid = 0 const LinkIDType undefined_linkid = 0
/** invalid key for key value */ /** invalid key for key value */
const KeyIDType invalid_key_value_key = 0 const KeyIDType invalid_key_value_key = 0
/** default distance used */ /** default distance used */
const MetricType default_distance = 1 const MetricType default_distance = 1
/** any distance larger than this will be considered infinity */ /** any distance larger than this will be considered infinity */
const MetricType infinite_distance = 0x7FFFFFFF const MetricType infinite_distance = 0x7FFFFFFF
/** represents invalid distance */ /** represents invalid distance */
const MetricType invalid_distance = 0 const MetricType invalid_distance = 0
const bool overload_default = false const bool overload_default = false
const bool flood_reduction_default = true const bool flood_reduction_default = true
/** default LIE FSM LIE TX internval time */ /** default LIE FSM LIE TX interval time */
const TimeIntervalInSecType default_lie_tx_interval = 1 const TimeIntervalInSecType default_lie_tx_interval = 1
/** default LIE FSM holddown time */ /** default LIE FSM holddown time */
const TimeIntervalInSecType default_lie_holdtime = 3 const TimeIntervalInSecType default_lie_holdtime = 3
/** multipler for default_lie_holdtime to hold down multiple neighbors */ /** multipler for default_lie_holdtime to hold down multiple neighbors */
const i8 multiple_neighbors_lie_holdtime_multipler = 4 const i8 multiple_neighbors_lie_holdtime_multipler = 4
/** default ZTP FSM holddown time */ /** default ZTP FSM holddown time */
const TimeIntervalInSecType default_ztp_holdtime = 1 const TimeIntervalInSecType default_ztp_holdtime = 1
/** by default LIE levels are ZTP offers */ /** by default LIE levels are ZTP offers */
const bool default_not_a_ztp_offer = false const bool default_not_a_ztp_offer = false
/** by default everyone is repeating flooding */ /** by default everyone is repeating flooding */
const bool default_you_are_flood_repeater = true const bool default_you_are_flood_repeater = true
/** 0 is illegal for SystemID */ /** 0 is illegal for System IDs */
const SystemIDType IllegalSystemID = 0 const SystemIDType IllegalSystemID = 0
/** empty set of nodes */ /** empty set of nodes */
const set<SystemIDType> empty_set_of_nodeids = {} const set<SystemIDType> empty_set_of_nodeids = {}
/** default lifetime of TIE is one week */ /** default lifetime of TIE is one week */
const LifeTimeInSecType default_lifetime = 604800 const LifeTimeInSecType default_lifetime = 604800
/** default lifetime when TIEs are purged is 5 minutes */ /** default lifetime when TIEs are purged is 5 minutes */
const LifeTimeInSecType purge_lifetime = 300 const LifeTimeInSecType purge_lifetime = 300
/** optional round down interval when TIEs are sent with security signatures /** optional round down interval when TIEs are sent with security signatures
to prevent excessive computation. **/ to prevent excessive computation. **/
const LifeTimeInSecType rounddown_lifetime_interval = 60 const LifeTimeInSecType rounddown_lifetime_interval = 60
/** any `TieHeader` that has a smaller lifetime difference /** any 'TieHeader' that has a smaller lifetime difference
than this constant is equal (if other fields equal). */ than this constant is equal (if other fields equal). */
const LifeTimeInSecType lifetime_diff2ignore = 400 const LifeTimeInSecType lifetime_diff2ignore = 400
/** default UDP port to run LIEs on */ /** default UDP port to run LIEs on */
const UDPPortType default_lie_udp_port = 914 const UDPPortType default_lie_udp_port = 914
/** default UDP port to receive TIEs on, that can be peer specific */ /** default UDP port to receive TIEs on, which can be peer specific */
const UDPPortType default_tie_udp_flood_port = 915 const UDPPortType default_tie_udp_flood_port = 915
/** default MTU link size to use */ /** default MTU link size to use */
const MTUSizeType default_mtu_size = 1400 const MTUSizeType default_mtu_size = 1400
/** default link being BFD capable */ /** default link being BFD capable */
const bool bfd_default = true const bool bfd_default = true
/** type used to target nodes with key value */ /** type used to target nodes with key value */
typedef i64 KeyValueTargetType typedef i64 KeyValueTargetType
/** default target for key value are all nodes. */ /** default target for key value are all nodes. */
const KeyValueTargetType keyvaluetarget_default = 0 const KeyValueTargetType keyvaluetarget_default = 0
/** value for _all leaves_ addressing. Represented by all bits set. */ /** value for _all leaves_ addressing. Represented by all bits set. */
const KeyValueTargetType keyvaluetarget_all_south_leaves = -1 const KeyValueTargetType keyvaluetarget_all_south_leaves = -1
/** undefined nonce, equivalent to missing nonce */ /** undefined nonce, equivalent to missing nonce */
const NonceType undefined_nonce = 0; const NonceType undefined_nonce = 0;
/** outer security Key ID, MUST be interpreted as in implementation /** outer security key ID, MUST be interpreted as in implementation
as unsigned */ as unsigned */
typedef i8 OuterSecurityKeyID typedef i8 OuterSecurityKeyID
/** security Key ID, MUST be interpreted as in implementation /** security key ID, MUST be interpreted as in implementation
as unsigned */ as unsigned */
typedef i32 TIESecurityKeyID typedef i32 TIESecurityKeyID
/** undefined key */ /** undefined key */
const TIESecurityKeyID undefined_securitykey_id = 0; const TIESecurityKeyID undefined_securitykey_id = 0;
/** Maximum delta (negative or positive) that a mirrored nonce can /** Maximum delta (negative or positive) that a mirrored nonce can
deviate from local value to be considered valid. */ deviate from local value to be considered valid. */
const i16 maximum_valid_nonce_delta = 5; const i16 maximum_valid_nonce_delta = 5;
const TimeIntervalInSecType nonce_regeneration_interval = 300; const TimeIntervalInSecType nonce_regeneration_interval = 300;
/** Direction of TIEs. */ /** Direction of TIEs. */
enum TieDirectionType { enum TieDirectionType {
Illegal = 0, Illegal = 0,
South = 1, South = 1,
North = 2, North = 2,
DirectionMaxValue = 3, DirectionMaxValue = 3,
} }
/** Address family type. */ /** Address family type. */
enum AddressFamilyType { enum AddressFamilyType {
Illegal = 0, Illegal = 0,
AddressFamilyMinValue = 1, AddressFamilyMinValue = 1,
IPv4 = 2, IPv4 = 2,
IPv6 = 3, IPv6 = 3,
AddressFamilyMaxValue = 4, AddressFamilyMaxValue = 4,
} }
/** IPv4 prefix type. */ /** IPv4 prefix type. */
struct IPv4PrefixType { struct IPv4PrefixType {
1: required IPv4Address address; 1: required IPv4Address address;
2: required PrefixLenType prefixlen; 2: required PrefixLenType prefixlen;
} }
/** IPv6 prefix type. */ /** IPv6 prefix type. */
struct IPv6PrefixType { struct IPv6PrefixType {
1: required IPv6Address address; 1: required IPv6Address address;
2: required PrefixLenType prefixlen; 2: required PrefixLenType prefixlen;
} }
/** IP address type. */ /** IP address type. */
union IPAddressType { union IPAddressType {
/** Content is IPv4 */ /** Content is IPv4 */
1: optional IPv4Address ipv4address; 1: optional IPv4Address ipv4address;
/** Content is IPv6 */ /** Content is IPv6 */
2: optional IPv6Address ipv6address; 2: optional IPv6Address ipv6address;
} }
/** Prefix advertisement. /** Prefix advertisement.
@note: for interface @note: For interface
addresses the protocol can propagate the address part beyond addresses, the protocol can propagate the address part beyond
the subnet mask and on reachability computation that has to the subnet mask and on reachability computation that has to
be normalized. The non-significant bits can be used be normalized. The non-significant bits can be used
for operational purposes. for operational purposes.
*/ */
union IPPrefixType { union IPPrefixType {
1: optional IPv4PrefixType ipv4prefix; 1: optional IPv4PrefixType ipv4prefix;
2: optional IPv6PrefixType ipv6prefix; 2: optional IPv6PrefixType ipv6prefix;
} }
/** Sequence of a prefix in case of move. /** Sequence of a prefix in case of move.
*/ */
struct PrefixSequenceType { struct PrefixSequenceType {
1: required IEEE802_1ASTimeStampType timestamp; 1: required IEEE802_1ASTimeStampType timestamp;
/** Transaction ID set by client in e.g. in 6LoWPAN. */ /** Transaction ID set by the client in, e.g., 6LoWPAN. */
2: optional PrefixTransactionIDType transactionid; 2: optional PrefixTransactionIDType transactionid;
} }
/** Type of TIE. /** Type of TIE.
*/ */
enum TIETypeType { enum TIETypeType {
Illegal = 0, Illegal = 0,
TIETypeMinValue = 1, TIETypeMinValue = 1,
/** first legal value */ /** first legal value */
NodeTIEType = 2, NodeTIEType = 2,
PrefixTIEType = 3, PrefixTIEType = 3,
PositiveDisaggregationPrefixTIEType = 4, PositiveDisaggregationPrefixTIEType = 4,
NegativeDisaggregationPrefixTIEType = 5, NegativeDisaggregationPrefixTIEType = 5,
PGPrefixTIEType = 6, PGPrefixTIEType = 6,
KeyValueTIEType = 7, KeyValueTIEType = 7,
ExternalPrefixTIEType = 8, ExternalPrefixTIEType = 8,
PositiveExternalDisaggregationPrefixTIEType = 9, PositiveExternalDisaggregationPrefixTIEType = 9,
TIETypeMaxValue = 10, TIETypeMaxValue = 10,
} }
/** RIFT route types. /** RIFT route types.
@note: The only purpose of those values is to introduce an @note: The only purpose of those values is to introduce an
ordering whereas an implementation can choose internally ordering, whereas an implementation can internally choose
any other values as long the ordering is preserved any other values as long the ordering is preserved.
*/ */
enum RouteType { enum RouteType {
Illegal = 0, Illegal = 0,
RouteTypeMinValue = 1, RouteTypeMinValue = 1,
/** First legal value. */ /** First legal value. */
/** Discard routes are most preferred */ /** Discard routes are most preferred */
Discard = 2, Discard = 2,
/** Local prefixes are directly attached prefixes on the /** Local prefixes are directly attached prefixes on the
* system such as e.g. interface routes. * system, such as interface routes.
*/ */
LocalPrefix = 3, LocalPrefix = 3,
/** Advertised in S-TIEs */ /** Advertised in S-TIEs */
SouthPGPPrefix = 4, SouthPGPPrefix = 4,
/** Advertised in N-TIEs */ /** Advertised in N-TIEs */
NorthPGPPrefix = 5, NorthPGPPrefix = 5,
/** Advertised in N-TIEs */ /** Advertised in N-TIEs */
NorthPrefix = 6, NorthPrefix = 6,
/** Externally imported north */ /** Externally imported north */
NorthExternalPrefix = 7, NorthExternalPrefix = 7,
/** Advertised in S-TIEs, either normal prefix or positive /** Advertised in S-TIEs, either normal prefix or positive
disaggregation */ disaggregation */
SouthPrefix = 8, SouthPrefix = 8,
/** Externally imported south */ /** Externally imported south */
SouthExternalPrefix = 9, SouthExternalPrefix = 9,
/** Negative, transitive prefixes are least preferred */ /** Negative, transitive prefixes are least preferred */
NegativeSouthPrefix = 10, NegativeSouthPrefix = 10,
RouteTypeMaxValue = 11, RouteTypeMaxValue = 11,
} }
enum KVTypes { enum KVTypes {
Experimental = 1, Experimental = 1,
WellKnown = 2, WellKnown = 2,
OUI = 3, OUI = 3,
} }
7.3. encoding.thrift 7.3. encoding.thrift
/** /**
Thrift file for packet encodings for RIFT Thrift file for packet encodings for RIFT
*/ */
include "common.thrift" include "common.thrift"
namespace py encoding namespace py encoding
/** Represents protocol encoding schema major version */ /** Represents protocol encoding schema major version */
const common.VersionType protocol_major_version = 8 const common.VersionType protocol_major_version = 8
/** Represents protocol encoding schema minor version */ /** Represents protocol encoding schema minor version */
const common.MinorVersionType protocol_minor_version = 0 const common.MinorVersionType protocol_minor_version = 0
/** Common RIFT packet header. */
struct PacketHeader {
/** Major version of protocol. */
1: required common.VersionType major_version =
protocol_major_version;
/** Minor version of protocol. */
2: required common.MinorVersionType minor_version =
protocol_minor_version;
/** Node sending the packet, in case of LIE/TIRE/TIDE
also the originator of it. */
3: required common.SystemIDType sender;
/** Level of the node sending the packet, required on everything
except LIEs. Lack of presence on LIEs indicates UNDEFINED_LEVEL
and is used in ZTP procedures.
*/
4: optional common.LevelType level;
}
/** Prefix community. */ /** Common RIFT packet header. */
struct Community { struct PacketHeader {
/** Higher order bits */ /** Major version of protocol. */
1: required i32 top; 1: required common.VersionType major_version =
/** Lower order bits */ protocol_major_version;
2: required i32 bottom; /** Minor version of protocol. */
} 2: required common.MinorVersionType minor_version =
protocol_minor_version;
/** Node sending the packet, in case of LIE/TIRE/TIDE
also the originator of it. */
3: required common.SystemIDType sender;
/** Level of the node sending the packet, required on everything
except LIEs. Lack of presence on LIEs indicates
UNDEFINED_LEVEL and is used in ZTP procedures.
*/
4: optional common.LevelType level;
}
/** Neighbor structure. */ /** Prefix community. */
struct Neighbor { struct Community {
/** System ID of the originator. */ /** Higher order bits */
1: required common.SystemIDType originator; 1: required i32 top;
/** ID of remote side of the link. */ /** Lower order bits */
2: required common.LinkIDType remote_id; 2: required i32 bottom;
} }
/** Capabilities the node supports. */ /** Neighbor structure. */
struct NodeCapabilities { struct Neighbor {
/** Must advertise supported minor version dialect that way. */ /** System ID of the originator. */
1: required common.MinorVersionType protocol_minor_version = 1: required common.SystemIDType originator;
protocol_minor_version; /** ID of remote side of the link. */
/** indicates that node supports flood reduction. */ 2: required common.LinkIDType remote_id;
2: optional bool flood_reduction = }
common.flood_reduction_default;
/** indicates place in hierarchy, i.e. top-of-fabric or
leaf only (in ZTP) or support for leaf-2-leaf
procedures. */
3: optional common.HierarchyIndications hierarchy_indications;
} /** Capabilities the node supports. */
struct NodeCapabilities {
/** Must advertise supported minor version dialect that way. */
1: required common.MinorVersionType protocol_minor_version =
protocol_minor_version;
/** indicates that node supports flood reduction. */
2: optional bool flood_reduction =
common.flood_reduction_default;
/** indicates place in hierarchy, i.e., top of fabric or
leaf only (in ZTP) or support for leaf-to-leaf
procedures. */
3: optional common.HierarchyIndications hierarchy_indications;
}
/** Link capabilities. */ /** Link capabilities. */
struct LinkCapabilities { struct LinkCapabilities {
/** Indicates that the link is supporting BFD. */ /** Indicates that the link is supporting BFD. */
1: optional bool bfd = 1: optional bool bfd =
common.bfd_default; common.bfd_default;
/** Indicates whether the interface will support IPv4 forwarding. */ /** Indicates whether the interface will support IPv4
2: optional bool ipv4_forwarding_capable = forwarding. */
true; 2: optional bool ipv4_forwarding_capable =
} true;
}
/** RIFT LIE Packet. /** RIFT LIE Packet.
@note: this node's level is already included on the packet header @note: This node's level is already included on the packet header.
*/ */
struct LIEPacket { struct LIEPacket {
/** Node or adjacency name. */ /** Node or adjacency name. */
1: optional string name; 1: optional string name;
/** Local link ID. */ /** Local link ID. */
2: required common.LinkIDType local_id; 2: required common.LinkIDType local_id;
/** UDP port to which we can receive flooded TIEs. */ /** UDP port to which we can receive flooded TIEs. */
3: required common.UDPPortType flood_port = 3: required common.UDPPortType flood_port =
common.default_tie_udp_flood_port; common.default_tie_udp_flood_port;
/** Layer 2 MTU, used to discover mismatch. */ /** Layer 2 MTU, used to discover mismatch. */
4: optional common.MTUSizeType link_mtu_size = 4: optional common.MTUSizeType link_mtu_size =
common.default_mtu_size; common.default_mtu_size;
/** Local link bandwidth on the interface. */ /** Local link bandwidth on the interface. */
5: optional common.BandwithInMegaBitsType 5: optional common.BandwidthInMegaBitsType
link_bandwidth = common.default_bandwidth; link_bandwidth = common.default_bandwidth;
/** Reflects the neighbor once received to provide /** Reflects the neighbor once received to provide
3-way connectivity. */ 3-way connectivity. */
6: optional Neighbor neighbor; 6: optional Neighbor neighbor;
/** Node's PoD. */ /** Node's PoD. */
7: optional common.PodType pod = 7: optional common.PodType pod =
common.default_pod; common.default_pod;
/** Node capabilities supported. */ /** Node capabilities supported. */
10: required NodeCapabilities node_capabilities; 10: required NodeCapabilities node_capabilities;
/** Capabilities of this link. */ /** Capabilities of this link. */
11: optional LinkCapabilities link_capabilities; 11: optional LinkCapabilities link_capabilities;
/** Required holdtime of the adjacency, i.e. for how /** Required holdtime of the adjacency, i.e., for how long a
long a period should adjacency be kept up without valid LIE reception. */ period adjacency should be kept up without valid LIE
12: required common.TimeIntervalInSecType reception. */
holdtime = common.default_lie_holdtime; 12: required common.TimeIntervalInSecType
/** Optional, unsolicited, downstream assigned locally significant label holdtime = common.default_lie_holdtime;
value for the adjacency. */ /** Optional, unsolicited, downstream assigned locally significant
13: optional common.LabelType label; label value for the adjacency. */
/** Indicates that the level on the LIE must not be used 13: optional common.LabelType label;
to derive a ZTP level by the receiving node. */ /** Indicates that the level on the LIE must not be used
21: optional bool not_a_ztp_offer = to derive a ZTP level by the receiving node. */
common.default_not_a_ztp_offer; 21: optional bool not_a_ztp_offer =
/** Indicates to northbound neighbor that it should common.default_not_a_ztp_offer;
be reflooding TIEs received from this node to achieve flood /** Indicates to northbound neighbor that it should
reduction and balancing for northbound flooding. */ be reflooding TIEs received from this node to achieve flood
22: optional bool you_are_flood_repeater = reduction and balancing for northbound flooding. */
common.default_you_are_flood_repeater; 22: optional bool you_are_flood_repeater =
/** Indicates to neighbor to flood node TIEs only and slow down common.default_you_are_flood_repeater;
all other TIEs. Ignored when received from southbound neighbor. */ /** Indicates to neighbor to flood node TIEs only and slow down
23: optional bool you_are_sending_too_quickly = all other TIEs. Ignored when received from southbound
false; neighbor. */
/** Instance name in case multiple RIFT instances running on same 23: optional bool you_are_sending_too_quickly =
interface. */ false;
24: optional string instance_name; /** Instance name in case multiple RIFT instances running on same
/** It provides the optional ID of the Fabric configured. This MUST match the information advertised interface. */
on the node element. */ 24: optional string instance_name;
35: optional common.FabricIDType fabric_id = common.default_fabric_id; /** It provides the optional ID of the fabric configured. This
MUST match the information advertised on the node element. */
35: optional common.FabricIDType fabric_id =
common.default_fabric_id;
} }
/** LinkID pair describes one of parallel links between two nodes. */ /** LinkID pair describes one of parallel links between two nodes. */
struct LinkIDPair { struct LinkIDPair {
/** Node-wide unique value for the local link. */ /** Node-wide unique value for the local link. */
1: required common.LinkIDType local_id; 1: required common.LinkIDType local_id;
/** Received remote link ID for this link. */ /** Received remote link ID for this link. */
2: required common.LinkIDType remote_id; 2: required common.LinkIDType remote_id;
/** Describes the local interface index of the link. */ /** Describes the local interface index of the link. */
10: optional common.PlatformInterfaceIndex platform_interface_index; 10: optional common.PlatformInterfaceIndex
/** Describes the local interface name. */ platform_interface_index;
11: optional string platform_interface_name; /** Describes the local interface name. */
/** Indicates whether the link is secured, i.e. protected by 11: optional string platform_interface_name;
outer key, absence of this element means no indication, /** Indicates whether the link is secured, i.e., protected by
undefined outer key means not secured. */ outer key, absence of this element means no indication,
12: optional common.OuterSecurityKeyID undefined outer key means not secured. */
trusted_outer_security_key; 12: optional common.OuterSecurityKeyID
/** Indicates whether the link is protected by established trusted_outer_security_key;
BFD session. */ /** Indicates whether the link is protected by established
13: optional bool bfd_up; BFD session. */
/** Optional indication which address families are up on the 13: optional bool bfd_up;
interface */ /** Optional indication which address families are up on the
14: optional set<common.AddressFamilyType> interface */
address_families; 14: optional set<common.AddressFamilyType>
} address_families;
}
/** Unique ID of a TIE. */ /** Unique ID of a TIE. */
struct TIEID { struct TIEID {
/** direction of TIE */ /** direction of TIE */
1: required common.TieDirectionType direction; 1: required common.TieDirectionType direction;
/** indicates originator of the TIE */ /** indicates originator of the TIE */
2: required common.SystemIDType originator; 2: required common.SystemIDType originator;
/** type of the tie */ /** type of the tie */
3: required common.TIETypeType tietype; 3: required common.TIETypeType tietype;
/** number of the tie */ /** number of the tie */
4: required common.TIENrType tie_nr; 4: required common.TIENrType tie_nr;
} }
/** Header of a TIE. */ /** Header of a TIE. */
struct TIEHeader { struct TIEHeader {
/** ID of the tie. */ /** ID of the tie. */
2: required TIEID tieid; 2: required TIEID tieid;
/** Sequence number of the tie. */ /** Sequence number of the tie. */
3: required common.SeqNrType seq_nr; 3: required common.SeqNrType seq_nr;
/** Absolute timestamp when the TIE was generated. */ /** Absolute timestamp when the TIE was generated. */
10: optional common.IEEE802_1ASTimeStampType origination_time; 10: optional common.IEEE802_1ASTimeStampType origination_time;
/** Original lifetime when the TIE was generated. */ /** Original lifetime when the TIE was generated. */
12: optional common.LifeTimeInSecType origination_lifetime; 12: optional common.LifeTimeInSecType origination_lifetime;
} }
/** Header of a TIE as described in TIRE/TIDE. /** Header of a TIE as described in TIRE/TIDE.
*/ */
struct TIEHeaderWithLifeTime { struct TIEHeaderWithLifeTime {
1: required TIEHeader header; 1: required TIEHeader header;
/** Remaining lifetime. */ /** Remaining lifetime. */
2: required common.LifeTimeInSecType remaining_lifetime; 2: required common.LifeTimeInSecType remaining_lifetime;
} }
/** TIDE with *sorted* TIE headers. */ /** TIDE with *sorted* TIE headers. */
struct TIDEPacket { struct TIDEPacket {
/** First TIE header in the tide packet. */ /** First TIE header in the TIDE packet. */
1: required TIEID start_range; 1: required TIEID start_range;
/** Last TIE header in the tide packet. */ /** Last TIE header in the TIDE packet. */
2: required TIEID end_range; 2: required TIEID end_range;
/** _Sorted_ list of headers. */ /** _Sorted_ list of headers. */
3: required list<TIEHeaderWithLifeTime> 3: required list<TIEHeaderWithLifeTime>
headers; headers;
} }
/** TIRE packet */ /** TIRE packet */
struct TIREPacket { struct TIREPacket {
1: required set<TIEHeaderWithLifeTime> 1: required set<TIEHeaderWithLifeTime>
headers; headers;
} }
/** neighbor of a node */
struct NodeNeighborsTIEElement {
/** level of neighbor */
1: required common.LevelType level;
/** Cost to neighbor. Ignore anything equal/larger than `infinite_distance` or equal `invalid_distance` */
3: optional common.MetricType cost
= common.default_distance;
/** can carry description of multiple parallel links in a TIE */
4: optional set<LinkIDPair>
link_ids;
/** total bandwith to neighbor as sum of all parallel links */
5: optional common.BandwithInMegaBitsType
bandwidth = common.default_bandwidth;
}
/** Indication flags of the node. */ /** neighbor of a node */
struct NodeFlags { struct NodeNeighborsTIEElement {
/** Indicates that node is in overload, do not transit traffic /** level of neighbor */
through it. */ 1: required common.LevelType level;
1: optional bool overload = common.overload_default; /** Cost to neighbor. Ignore anything equal/larger than
} 'infinite_distance' or equal 'invalid_distance' */
3: optional common.MetricType cost
= common.default_distance;
/** can carry description of multiple parallel links in a TIE */
4: optional set<LinkIDPair>
link_ids;
/** total bandwidth to neighbor as sum of all parallel links */
5: optional common.BandwidthInMegaBitsType
bandwidth = common.default_bandwidth;
}
/** Description of a node. */ /** Indication flags of the node. */
struct NodeTIEElement { struct NodeFlags {
/** Level of the node. */ /** Indicates that node is in overload, do not transit traffic
1: required common.LevelType level; through it. */
/** Node's neighbors. Multiple node TIEs can carry disjoint sets of neighbors. */ 1: optional bool overload = common.overload_default;
2: required map<common.SystemIDType, }
NodeNeighborsTIEElement> neighbors;
/** Capabilities of the node. */
3: required NodeCapabilities capabilities;
/** Flags of the node. */
4: optional NodeFlags flags;
/** Optional node name for easier operations. */
5: optional string name;
/** PoD to which the node belongs. */
6: optional common.PodType pod;
/** optional startup time of the node */
7: optional common.TimestampInSecsType startup_time;
/** If any local links are miscabled, this indication is flooded. */ /** Description of a node. */
10: optional set<common.LinkIDType> struct NodeTIEElement {
miscabled_links; /** Level of the node. */
1: required common.LevelType level;
/** Node's neighbors. Multiple node TIEs can carry disjoint sets
of neighbors. */
2: required map<common.SystemIDType,
NodeNeighborsTIEElement> neighbors;
/** Capabilities of the node. */
3: required NodeCapabilities capabilities;
/** Flags of the node. */
4: optional NodeFlags flags;
/** Optional node name for easier operations. */
5: optional string name;
/** PoD to which the node belongs. */
6: optional common.PodType pod;
/** Optional startup time of the node */
7: optional common.TimestampInSecsType startup_time;
/** ToFs in the same plane. Only carried by ToF. Multiple Node TIEs can carry disjoint sets of ToFs /** If any local links are miscabled, this indication is
which MUST be joined to form a single set. */ flooded. */
12: optional set<common.SystemIDType> 10: optional set<common.LinkIDType>
same_plane_tofs; miscabled_links;
/** It provides the optional ID of the Fabric configured */ /** ToFs in the same plane. Only carried by ToF. Multiple Node
20: optional common.FabricIDType fabric_id = common.default_fabric_id; TIEs can carry disjoint sets of ToFs that MUST be joined to
form a single set. */
12: optional set<common.SystemIDType>
same_plane_tofs;
} /** It provides the optional ID of the fabric configured */
20: optional common.FabricIDType fabric_id =
common.default_fabric_id;
/** Attributes of a prefix. */ }
struct PrefixAttributes {
/** Distance of the prefix. */
2: required common.MetricType metric
= common.default_distance;
/** Generic unordered set of route tags, can be redistributed
to other protocols or use within the context of real time
analytics. */
3: optional set<common.RouteTagType>
tags;
/** Monotonic clock for mobile addresses. */
4: optional common.PrefixSequenceType monotonic_clock;
/** Indicates if the prefix is a node loopback. */
6: optional bool loopback = false;
/** Indicates that the prefix is directly attached. */
7: optional bool directly_attached = true;
/** link to which the address belongs to. */
10: optional common.LinkIDType from_link;
/** Optional, per prefix significant label. */
12: optional common.LabelType label;
}
/** TIE carrying prefixes */ /** Attributes of a prefix. */
struct PrefixTIEElement { struct PrefixAttributes {
/** Prefixes with the associated attributes. */ /** Distance of the prefix. */
1: required map<common.IPPrefixType, PrefixAttributes> prefixes; 2: required common.MetricType metric
} = common.default_distance;
/** Generic unordered set of route tags, can be redistributed
to other protocols or used within the context of real time
analytics. */
3: optional set<common.RouteTagType>
tags;
/** Monotonic clock for mobile addresses. */
4: optional common.PrefixSequenceType monotonic_clock;
/** Indicates if the prefix is a node loopback. */
6: optional bool loopback = false;
/** Indicates that the prefix is directly attached. */
7: optional bool directly_attached = true;
/** Link to which the address belongs to. */
10: optional common.LinkIDType from_link;
/** Optional, per-prefix significant label. */
12: optional common.LabelType label;
}
/** Defines the targeted nodes and the value carried. */ /** TIE carrying prefixes */
struct KeyValueTIEElementContent { struct PrefixTIEElement {
1: optional common.KeyValueTargetType targets = common.keyvaluetarget_default; /** Prefixes with the associated attributes. */
2: optional binary value; 1: required map<common.IPPrefixType, PrefixAttributes> prefixes;
} }
/** Generic key value pairs. */ /** Defines the targeted nodes and the value carried. */
struct KeyValueTIEElement { struct KeyValueTIEElementContent {
1: required map<common.KeyIDType, KeyValueTIEElementContent> keyvalues; 1: optional common.KeyValueTargetType targets =
} common.keyvaluetarget_default;
2: optional binary value;
}
/** Single element in a TIE. */ /** Generic key value pairs. */
union TIEElement { struct KeyValueTIEElement {
/** Used in case of enum common.TIETypeType.NodeTIEType. */ 1: required map<common.KeyIDType, KeyValueTIEElementContent>
1: optional NodeTIEElement node; keyvalues;
/** Used in case of enum common.TIETypeType.PrefixTIEType. */ }
2: optional PrefixTIEElement prefixes;
/** Positive prefixes (always southbound). */
3: optional PrefixTIEElement positive_disaggregation_prefixes;
/** Transitive, negative prefixes (always southbound) */
5: optional PrefixTIEElement negative_disaggregation_prefixes;
/** Externally reimported prefixes. */
6: optional PrefixTIEElement external_prefixes;
/** Positive external disaggregated prefixes (always southbound). */
7: optional PrefixTIEElement
positive_external_disaggregation_prefixes;
/** Key-Value store elements. */
9: optional KeyValueTIEElement keyvalues;
}
/** TIE packet */ /** Single element in a TIE. */
struct TIEPacket { union TIEElement {
1: required TIEHeader header; /** Used in case of enum common.TIETypeType.NodeTIEType. */
2: required TIEElement element; 1: optional NodeTIEElement node;
} /** Used in case of enum common.TIETypeType.PrefixTIEType. */
2: optional PrefixTIEElement prefixes;
/** Positive prefixes (always southbound). */
3: optional PrefixTIEElement positive_disaggregation_prefixes;
/** Transitive, negative prefixes (always southbound) */
5: optional PrefixTIEElement negative_disaggregation_prefixes;
/** Externally reimported prefixes. */
6: optional PrefixTIEElement external_prefixes;
/** Positive external disaggregated prefixes (always
southbound). */
7: optional PrefixTIEElement
positive_external_disaggregation_prefixes;
/** Key-Value store elements. */
9: optional KeyValueTIEElement keyvalues;
}
/** Content of a RIFT packet. */ /** TIE packet */
union PacketContent { struct TIEPacket {
1: optional LIEPacket lie; 1: required TIEHeader header;
2: optional TIDEPacket tide; 2: required TIEElement element;
3: optional TIREPacket tire; }
4: optional TIEPacket tie;
}
/** RIFT packet structure. */ /** Content of a RIFT packet. */
struct ProtocolPacket { union PacketContent {
1: required PacketHeader header; 1: optional LIEPacket lie;
2: required PacketContent content; 2: optional TIDEPacket tide;
} 3: optional TIREPacket tire;
4: optional TIEPacket tie;
}
/** RIFT packet structure. */
struct ProtocolPacket {
1: required PacketHeader header;
2: required PacketContent content;
}
8. Further Details on Implementation 8. Further Details on Implementation
8.1. Considerations for Leaf-Only Implementation 8.1. Considerations for Leaf-Only Implementation
RIFT can and is intended to be stretched to the lowest level in the RIFT can and is intended to be stretched to the lowest level in the
IP fabric to integrate ToRs or even servers. Since those entities IP fabric to integrate ToRs or even servers. Since those entities
would run as leaves only, it is worth to observe that a leaf only would run as leaves only, it is worth it to observe that a leaf-only
version is significantly simpler to implement and requires much less version is significantly simpler to implement and requires much less
resources: resources:
1. Leaf nodes only need to maintain a multipath default route under 1. Leaf nodes only need to maintain a multipath default route under
normal circumstances. However, in cases of catastrophic normal circumstances. However, in cases of catastrophic
partitioning, leaf nodes SHOULD be capable of accommodating all partitioning, leaf nodes SHOULD be capable of accommodating all
the leaf routes in their own PoD to prevent traffic loss. the leaf routes in their own PoD to prevent traffic loss.
2. Leaf nodes hold only their own North TIEs and the South TIEs of 2. Leaf nodes only hold their own North TIEs and the South TIEs of
Level 1 nodes they are connected to. level 1 nodes they are connected to.
3. Leaf nodes do not have to support any type of disaggregation 3. Leaf nodes do not have to support any type of disaggregation
computation or propagation. computation or propagation.
4. Leaf nodes are not required to support the overload flag. 4. Leaf nodes are not required to support the overload flag.
5. Leaf nodes do not need to originate S-TIEs unless optional leaf- 5. Leaf nodes do not need to originate S-TIEs unless optional leaf-
2-leaf features are desired. to-leaf features are desired.
8.2. Considerations for Spine Implementation 8.2. Considerations for Spine Implementation
Nodes that do not act as ToF are not required to discover fallen Nodes that do not act as ToF are not required to discover fallen
leaves by comparing reachable destinations with peers and therefore leaves by comparing reachable destinations with peers and therefore
do not need to run the computation of disaggregated routes based on do not need to run the computation of disaggregated routes based on
that discovery. On the other hand, non-ToF nodes need to respect that discovery. On the other hand, non-ToF nodes need to respect
disaggregated routes advertised from the north. In the case of disaggregated routes advertised from the north. In the case of
negative disaggregation, spines nodes need to generate southbound negative disaggregation, spines nodes need to generate southbound
disaggregated routes when all parents are lost for a fallen leaf. disaggregated routes when all parents are lost for a fallen leaf.
9. Security Considerations 9. Security Considerations
9.1. General 9.1. General
One can consider attack vectors where a router may reboot many times One can consider attack vectors where a router may reboot many times
while changing its System ID and pollute the network with many stale while changing its System ID and pollute the network with many stale
TIEs or TIEs that are sent with very long lifetimes and not cleaned TIEs or TIEs that are sent with very long lifetimes and not cleaned
up when the routes vanish. Those attack vectors are not unique to up when the routes vanish. Those attack vectors are not unique to
RIFT. Given large memory footprints available today those attacks RIFT. Given large memory footprints available today, those attacks
should be relatively benign. Otherwise, a node SHOULD implement a should be relatively benign. Otherwise, a node SHOULD implement a
strategy of discarding contents of all TIEs that were not present in strategy of discarding contents of all TIEs that were not present in
the SPF tree over a certain, configurable period of time. Since the the SPF tree over a certain, configurable period of time. Since the
protocol is self-stabilizing and will advertise the presence of such protocol is self-stabilizing and will advertise the presence of such
TIEs to its neighbors, they can be re-requested again if a TIEs to its neighbors, they can be re-requested again if a
computation finds that it has an adjacency formed towards the System computation finds that it has an adjacency formed towards the System
ID of the discarded TIEs. ID of the discarded TIEs.
The inner protection configured based on any of the mechanisms in The inner protection configured based on any of the mechanisms in
Section 10.2 guarantees the integrity of TIE content and when Section 10.2 guarantees the integrity of TIE content, and when
combined with outer part of the envelope using any of the mechanisms combined with the outer part of the envelope, using any of the
in Section 10.2 guarantees protection against replay attacks as well. mechanisms in Section 10.2, guarantees protection against replay
If only outer protection (i.e., an outer key ID different from attacks as well. If only outer protection (i.e., an outer key ID
`undefined_securitykey_id`) is applied to an adjacency by the means different from 'undefined_securitykey_id') is applied to an adjacency
of any mechanism in Section 10.2 the integrity of the packet and by the means of any mechanism in Section 10.2, the integrity of the
replay protection is guaranteed only over the adjacency involved in packet and replay protection is guaranteed only over the adjacency
any of the configured directions. Further considerations can be involved in any of the configured directions. Further considerations
found in Section 9.7 and Section 9.8. can be found in Sections 9.7 and 9.8.
9.2. Time to Live and Hop Limit Values 9.2. Time to Live and Hop Limit Values
RIFT explicitly requires the use of a TTL/HL value of 1 *or* 255 when RIFT explicitly requires the use of a TTL/HL value of 1 *or* 255 when
sending/receiving LIEs and TIEs so that implementors have a choice sending/receiving LIEs and TIEs so that implementors have a choice
between the two. between the two.
Using a TTL/HL value of 255 does come with security concerns, but Using a TTL/HL value of 255 does come with security concerns, but
those risks are addressed in [RFC5082]. However, this approach may those risks are addressed in [RFC5082]. However, this approach may
still have difficulties with some forwarding implementations (e.g. still have difficulties with some forwarding implementations (e.g.,
incorrectly processing TTL/HL, loops within forwarding plane itself, incorrectly processing TTL/HL, loops within the forwarding plane
etc.). itself, etc.).
It is for this reason that RIFT also allows implementations to use a It is for this reason that RIFT also allows implementations to use a
TTL/HL of 1. Attacks that exploit this by spoofing it from several TTL/HL of 1. Attacks that exploit this by spoofing it from several
hops away are indeed possible, but are exceptionally difficult to hops away are indeed possible but are exceptionally difficult to
engineer. Replay attacks are another potential attack vector, but as engineer. Replay attacks are another potential attack vector, but as
described in the subsequent security sections, RIFT is well protected described in the subsequent security sections, RIFT is well protected
against such attacks if any of the mechanisms in Section 10.2 is against such attacks if any of the mechanisms in Section 10.2 are
applied. Additionally, for link-local scoped multicast addresses applied. Additionally, for link-local scoped multicast addresses
used for LIE the value of 1 presents a more consistent choice. used for LIE, the value of 1 presents a more consistent choice.
9.3. Malformed Packets 9.3. Malformed Packets
The protocol protects packets extensively through optional signatures The protocol protects packets extensively through optional signatures
and nonces so if the possibility of maliciously injected malformed or and nonces, so if the possibility of maliciously injected malformed
replayed packets exist in a deployment algorithms in Section 10.2 or replayed packets exist in a deployment, algorithms in Section 10.2
must be applied. must be applied.
Even with the security envelope, since RIFT relies on Thrift encoders Even with the security envelope, since RIFT relies on Thrift encoders
and decoders generated automatically from IDL it is conceivable that and decoders generated automatically from IDL, it is conceivable that
errors in such encoders/decoders could be discovered and lead to errors in such encoders/decoders could be discovered and lead to
delivery of corrupted packets or reception of packets that cannot be delivery of corrupted packets or reception of packets that cannot be
decoded. Misformatted packets lead normally to decoder returning an decoded. Misformatted packets normally lead to the decoder returning
error condition to the caller and with that the packet is basically an error condition to the caller, and with that, the packet is
unparsable with no other choice but to discard it. Should the basically unparsable with no other choice but to discard it. Should
unlikely scenario occur of the decoder being forced to abort the the unlikely scenario occur of the decoder being forced to abort the
protocol this is neither better nor worse than today's behavior of protocol, this is neither better nor worse than today's behavior of
other protocols. other protocols.
9.4. RIFT ZTP 9.4. RIFT ZTP
Section 6.7 presents many attack vectors in untrusted environments, Section 6.7 presents many attack vectors in untrusted environments,
starting with nodes that oscillate their level offers to the starting with nodes that oscillate their level offers to the
possibility of nodes offering a _ThreeWay_ adjacency with the highest possibility of nodes offering a _ThreeWay_ adjacency with the highest
possible level value and a very long holdtime trying to put itself possible level value and a very long holdtime trying to put itself
"on top of the lattice" thereby allowing it to gain access to the "on top of the lattice", thereby allowing it to gain access to the
whole southbound topology. Session authentication mechanisms are whole southbound topology. Session authentication mechanisms are
necessary in environments where this is possible and RIFT provides necessary in environments where this is possible, and RIFT provides
the security envelope to ensure this if so desired if any mechanism the security envelope to ensure this, if so desired, if any mechanism
in Section 10.2 is deployed. in Section 10.2 is deployed.
9.5. Lifetime 9.5. Lifetime
RIFT removes lifetime modification and replay attack vectors by RIFT removes lifetime modification and replay attack vectors by
protecting the lifetime behind a signature computed over it and protecting the lifetime behind a signature computed over it and
additional nonce combination which results in the inability of an additional nonce combination, which results in the inability of an
attacker to artificially shorten the _remaining_lifetime_. This only attacker to artificially shorten the _remaining_lifetime_. This only
applies if any mechanism in Section 10.2 is used. applies if any mechanism in Section 10.2 is used.
9.6. Packet Number 9.6. Packet Number
An optional defined value number that is carried in the security A packet number is an optional defined value number that is carried
envelope without any fingerprint protection and is hence vulnerable in the security envelope without any fingerprint protection and is
to replay and modification attacks. Contrary to nonces, this number hence vulnerable to replay and modification attacks. Contrary to
must change on every packet and would present a very high nonces, this number must change on every packet and would present a
cryptographic load if signed. The attack vector packet number very high cryptographic load if signed. The attack vector packet
present is relatively benign. Changing the packet number by a man- number present is relatively benign. Changing the packet number by a
in-the-middle attack will only affect operational validation tools man-in-the-middle attack will only affect operational validation
and possibly some performance optimizations on flooding. It is tools and possibly some performance optimizations on flooding. It is
expected that an implementation detecting too many "fake losses" or expected that an implementation detecting too many "fake losses" or
"misorderings" due to the attack on the packet number would simply "misorderings" due to the attack on the packet number would simply
suppress its further processing. suppress its further processing.
9.7. Outer Fingerprint Attacks 9.7. Outer Fingerprint Attacks
Even when a mechanism in Section 10.2 is enabled to generate outer Even when a mechanism in Section 10.2 is enabled to generate outer
fingerprints further attack considerations apply. fingerprints, further attack considerations apply.
A node can try to inject LIE packets observing a conversation on the A node can try to inject LIE packets observing a conversation on the
wire by using the observed outer Key ID albeit it cannot generate wire by using the observed outer key ID, albeit it cannot generate
valid signatures in case it changes the integrity of the message so valid signatures in case it changes the integrity of the message, so
the only possible attack is DoS due to excessive LIE validation if the only possible attack is DoS due to excessive LIE validation if
any mechanism in Section 10.2 is used. any mechanism in Section 10.2 is used.
A node can try to replay previous LIEs with changed state that it A node can try to replay previous LIEs with a changed state that it
recorded but the attack is hard to replicate since the nonce recorded, but the attack is hard to replicate since the nonce
combination must match the ongoing exchange and is then limited to a combination must match the ongoing exchange and is then limited to
single flap only since both nodes will advance their nonces in case only a single flap since both nodes will advance their nonces in case
the adjacency state changed. Even in the most unlikely case the the adjacency state changed. Even in the most unlikely case, the
attack length is limited due to both sides periodically increasing attack length is limited due to both sides periodically increasing
their nonces. their nonces.
Generally, since weak nonces are not changed on every packet for Generally, since weak nonces are not changed on every packet for
performance reasons a conceivable attack vector by a man-in-the- performance reasons, a conceivable attack vector by a man in the
middle is to flood a receiving node with maximum bandwidth of middle is to flood a receiving node with the maximum bandwidth of
recently observed packets, both LIEs as well as TIEs. In a scenario recently observed packets, both LIEs as well as TIEs. In a scenario
where such attacks are likely _maximum_valid_nonce_delta_ can be where such attacks are likely, _maximum_valid_nonce_delta_ can be
implemented as configurable, small value and implemented as configurable, small value and
_nonce_regeneration_interval_ configured to very small value as well. _nonce_regeneration_interval_ configured to very small value as well.
This will likely present a significant computational load on large This will likely present a significant computational load on large
fabrics under normal operation. fabrics under normal operation.
9.8. TIE Origin Fingerprint DoS Attacks 9.8. TIE Origin Fingerprint DoS Attacks
Even when a mechanism in Section 10.2 is enabled to generate inner Even when a mechanism in Section 10.2 is enabled to generate inner
fingerprints or signatures further attack considerations apply. fingerprints or signatures, further attack considerations apply.
In case the inner fingerprint could be generated by a compromised In case the inner fingerprint could be generated by a compromised
node in the network other than the originator based on shared secrets node in the network other than the originator based on shared
the deployment must fall back on use of signatures that can be secrets, the deployment must fall back on use of signatures that can
validated but not generated by any other node but the originator. be validated but not generated by any other node except the
originator.
A compromised node in the network can attempt to brute force "fake A compromised node in the network can attempt to brute force "fake
TIEs" using other nodes' TIE origin key identifiers without TIEs" using other nodes' TIE origin key identifiers without
possessing the necessary secrets. Albeit the ultimate validation of possessing the necessary secrets. Albeit the ultimate validation of
the origin signature will fail in such scenarios and not progress the origin signature will fail in such scenarios and not progress
further than immediately peering nodes, the resulting denial of further than immediately peering nodes, the resulting DoS attack
service attack seems unavoidable since the TIE origin Key ID is only seems unavoidable since the TIE origin key ID is only protected by
protected by the (here assumed to be compromised) node. the (here assumed to be compromised) node.
9.9. Host Implementations 9.9. Host Implementations
It can be reasonably expected that with the proliferation of RotH It can be reasonably expected that the proliferation of RotH servers,
servers, rather than dedicated networking devices, will represent a rather than dedicated networking devices, will represent a
significant amount of RIFT devices. Given their normally far wider significant amount of RIFT devices. Given their normally far wider
software envelope and access granted to them, such servers are also software envelope and access granted to them, such servers are also
far more likely to be compromised and present an attack vector on the far more likely to be compromised and present an attack vector on the
protocol. Hijacking of prefixes to attract traffic is a trust protocol. Hijacking of prefixes to attract traffic is a trust
problem and cannot be easily addressed within the protocol if the problem and cannot be easily addressed within the protocol if the
trust model is breached, i.e. the server presents valid credentials trust model is breached, i.e., the server presents valid credentials
to form an adjacency and issue TIEs. In an even more devious way, to form an adjacency and issue TIEs. In an even more devious way,
the servers can present DoS (or even DDoS) vectors of issuing too the servers can present DoS (or even DDoS) vectors from issuing too
many LIE packets, flooding large amounts of North TIEs, and many LIE packets, flooding large amounts of North TIEs, and
attempting similar resource overrun attacks. A prudent attempting similar resource overrun attacks. A prudent
implementation forming adjacencies to leaves should implement implementation forming adjacencies to leaves should implement
thresholds mechanisms and raise warnings when, e.g., a leaf is threshold mechanisms and raise warnings when, e.g., a leaf is
advertising an excess number of TIEs or prefixes. Additionally, such advertising an excess number of TIEs or prefixes. Additionally, such
implementation could refuse any topology information except the implementation could refuse any topology information except the
node's own TIEs and authenticated, reflected South Node TIEs at own node's own TIEs and authenticated, reflected South Node TIEs at their
level. own level.
To isolate possible attack vectors on the leaf to the largest To isolate possible attack vectors on the leaf to the largest
possible extent a dedicated leaf-only implementation could run possible extent, a dedicated leaf-only implementation could run
without any configuration by hard-coding a well-known adjacency key without any configuration by hard-coding a well-known adjacency key
(which can be always rolled-over by the means of, e.g., well-known (which can be always rolled over by the means of, e.g., a well-known
key-value distributed from top of the fabric), leaf level value and key value distributed from the top of the fabric), leaf level value
always setting overload flag. All other values can be derived by and always setting overload flag. All other values can be derived by
automatic means as described above. automatic means as described above.
9.9.1. IPv4 Broadcast and IPv6 All Routers Multicast Implementations 9.9.1. IPv4 Broadcast and IPv6 All-Routers Multicast Implementations
Section 6.2 describes an optional implementation that supports LIE Section 6.2 describes an optional implementation that supports LIE
exchange over IPv4 broadcast addresses and/or the IPv6 all routers exchange over IPv4 broadcast addresses and/or the IPv6 all-routers
multicast address. It is important to consider that if an multicast address. It is important to consider that if an
implementation supports this, the attack surface widens as LIEs may implementation supports this, the attack surface widens as LIEs may
be propagated to devices outside of the intended RIFT topology. This be propagated to devices outside of the intended RIFT topology. This
may leave RIFT nodes more susceptible to the various attack vectors may leave RIFT nodes more susceptible to the various attack vectors
already described in this section. already described in this section.
10. IANA Considerations 10. IANA Considerations
This specification requests multicast address assignments and As detailed below, multicast addresses and standard port numbers have
standard port numbers. Additionally, registries for the schema are been assigned. Additionally, registries for the schema have been
requested and suggested values provided that reflect the numbers created with initial values assigned.
allocated in the given schema.
10.1. Requested Multicast and Port Numbers 10.1. Multicast and Port Numbers
This document requests allocation in the 'IPv4 Multicast Address In the "IPv4 Multicast Address Space" registry, the value of
Space' registry the suggested value of 224.0.0.121 as 224.0.0.121 has been assigned for 'ALL_V4_RIFT_ROUTERS'. In the
'ALL_V4_RIFT_ROUTERS' and in the 'IPv6 Multicast Address Space' "IPv6 Multicast Address Space" registry, the value of ff02::a1f7 has
registry the suggested value of ff02::a1f7 as 'ALL_V6_RIFT_ROUTERS'. been assigned for 'ALL_V6_RIFT_ROUTERS'.
This document requests the following allocations from the "Service The following assignments have been made in the "Service Name and
Name and Transport Protocol Port Number Registry": Transport Protocol Port Number Registry":
_RIFT LIE Port_ _RIFT LIE Port_
Service Name: rift-lies
Transport Protocol(s): UDP Service Name: rift-lies
Assignee: Tony Przygienda (prz@juniper.net) Port Number: 914
Contact: Jordan Head (jhead@juniper.net) Transport Protocol: udp
Description: Routing in Fat Trees Link Information Element Description: Routing in Fat Trees Link Information Element
Reference: This Document Assignee: IESG (iesg@ietf.org)
Port Number: 914 Contact: IETF Chair (chair@ietf.org)
Reference: RFC 9692
_RIFT TIE Port_ _RIFT TIE Port_
Service Name: rift-ties Service Name: rift-ties
Transport Protocol(s): UDP Port Number: 915
Assignee: Tony Przygienda (prz@juniper.net) Transport Protocol: udp
Contact: Jordan Head (jhead@juniper.net) Assignee: IESG (iesg@ietf.org)
Description: Routing in Fat Trees Topology Information Element Contact: IETF Chair (chair@ietf.org)
Reference: This Document Description: Routing in Fat Trees Topology Information Element
Port Number: 915 Reference: RFC 9692
10.2. Requested Registry for RIFT Security Algorithms 10.2. Registry for RIFT Security Algorithms
This section requests generation of a new registry holding the A new registry has been created to hold the allowed RIFT security
allowed RIFT Security Algorithms. No particular enumeration values algorithms. No particular enumeration values are necessary since
are necessary since RIFT uses a key ID abstraction on packets without RIFT uses a key ID abstraction on packets without disclosing any
disclosing any information about the algorithm or secrets used and information about the algorithm or secrets used and only carries the
only carries the resulting fingerprint or signature protecting the resulting fingerprint or signature protecting the integrity of the
integrity of the data. data.
The registry applies the "Specification Required" policy per The registry applies the "Specification Required" policy per
[RFC5226]. The designated expert should ensure that the algorithms [RFC8126]. The designated expert should ensure that the algorithms
suggested represent the state of the art at a given point in time and suggested represent the state of the art at a given point in time and
avoid introducing algorithms which do not represent enhanced security avoid introducing algorithms that do not represent enhanced security
properties or ensure such properties at lower cost as compared to properties or ensure such properties at a lower cost as compared to
existing registry entries. existing registry entries.
+==========================+===========+==========================+ +==========================+============+==========================+
| Name | Reference | Recommendation | | Name | Reference | Recommendation |
+==========================+===========+==========================+ +==========================+============+==========================+
| HMAC-SHA256 | [SHA-2] | Simplest way to ensure | | HMAC-SHA256 | [SHA-2] | Simplest way to ensure |
| | and | integrity of | | | and | integrity of |
| | [RFC2104] | transmissions across | | | [RFC2104] | transmissions across |
| | | adjacencies when used as | | | | adjacencies when used as |
| | | outer key and integrity | | | | outer key and integrity |
| | | of TIEs when used as | | | | of TIEs when used as |
| | | inner keys. Recommended | | | | inner keys. Recommended |
| | | for most interoperable | | | | for most interoperable |
| | | security protection. | | | | security protection. |
+--------------------------+-----------+--------------------------+ +--------------------------+------------+--------------------------+
| HMAC-SHA512 | [SHA-2] | Same as HMAC-SHA256 with | | HMAC-SHA512 | [SHA-2] | Same as HMAC-SHA256 with |
| | and | stronger protection. | | | and | stronger protection. |
| | [RFC2104] | | | | [RFC2104] | |
+--------------------------+-----------+--------------------------+ +--------------------------+------------+--------------------------+
| SHA256-RSASSA-PKCS1-v1_5 | [RFC8017] | Recommended for high | | SHA256-RSASSA-PKCS1-v1_5 | [RFC8017], | Recommended for high |
| | Section | security applications | | | Section | security applications |
| | 8.2 | where private keys are | | | 8.2 | where private keys are |
| | | protected by according | | | | protected by according |
| | | nodes. Recommended as | | | | nodes. Recommended as |
| | | well in case not only | | | | well in case not only |
| | | integrity but origin | | | | integrity but origin |
| | | validation is necessary | | | | validation is necessary |
| | | for TIEs. Recommended | | | | for TIEs. Recommended |
| | | when adjacencies must be | | | | when adjacencies must be |
| | | protected without | | | | protected without |
| | | disclosing the secrets | | | | disclosing the secrets |
| | | on both sides of the | | | | on both sides of the |
| | | adjacency. | | | | adjacency. |
+--------------------------+-----------+--------------------------+ +--------------------------+------------+--------------------------+
| SHA512-RSASSA-PKCS1-v1_5 | [RFC8017] | Same as SHA256-RSASSA- | | SHA512-RSASSA-PKCS1-v1_5 | [RFC8017] | Same as SHA256-RSASSA- |
| | | PKCS1-v1_5 with stronger | | | | PKCS1-v1_5 with stronger |
| | | protection. | | | | protection. |
+--------------------------+-----------+--------------------------+ +--------------------------+------------+--------------------------+
Table 7 Table 7
10.3. Requested Registries with Assigned Values for Schema Values 10.3. Registries with Assigned Values for Schema Values
This section requests registries that help govern the schema via This section requests registries that help govern the schema via the
usual IANA registry procedures. A top-level group named 'RIFT' usual IANA registry procedures. The registry group "Routing in Fat
should hold the corresponding registries requested in the following Trees (RIFT)" holds the following registries. Registry values are
sections with their pre-defined values. Registry values are stored stored with their minimum and maximum version in which they are
with their minimum and maximum version in which they are available. available. All values not provided are to be considered
All values not provided as to be considered `Unassigned`. The range "Unassigned". The range of every registry is a 16-bit integer.
of every registry is a 16-bit integer. Allocation of new values is Allocation of new values is performed via "Expert Review" action only
performed via `Expert Review` action in case of major or minor Change in the case of minor changes per the rules in Section 7. All other
per rules in Section 7. Any other allocation is performed via allocations are performed via "Specification Required".
'Specification Required'.
The registries do not contain in some cases necessary information In some cases, the registries do not contain necessary information
such as whether the fields are optional or required, what units are such as whether the fields are optional or required, what units are
used or what datatype is involved. This information is encoded in used, or what datatype is involved. This information is encoded in
the normative schema itself by the means of IDL syntax or necessary the normative schema itself by the means of IDL syntax or necessary
type definitions and their names. type definitions and their names.
10.3.1. Registry RIFT/Versions 10.3.1. RIFTVersions Registry
This registry stores all RIFT protocol schema major and minor This registry stores all RIFT protocol schema major and minor
versions including the reference to the document introducing the versions, including the reference to the document introducing the
version. This means as well that if multiple documents extend rift version. This also means that, if multiple documents extend rift
schema they have to serialize using this registry to increase the schema, they have to serialize using this registry to increase the
minor or major versions sequentially. minor or major versions sequentially.
+================+===================================+ +================+=====================+
| Schema Version | Reference | | Schema Version | Reference |
+================+===================================+ +================+=====================+
| 8.0 | https://datatracker.ietf.org/doc/ | | 8.0 | RFC 9692, Section 7 |
| | draft-ietf-rift-rift/ Section 7 | +----------------+---------------------+
+----------------+-----------------------------------+
Table 8
10.3.2. Registry RIFT/common/AddressFamilyType
The name of the registry should be RIFTCommonAddressFamilyType. Table 8
Address family type. 10.3.2. RIFTCommonAddressFamilyType Registry
+=======================+=======+=============+=========+=========+ This registry has the following initial values.
| Name | Value | Min. Schema | Max. | Comment |
| | | Version | Schema | |
| | | | Version | |
+=======================+=======+=============+=========+=========+
| Illegal | 0 | 8.0 | | |
+-----------------------+-------+-------------+---------+---------+
| AddressFamilyMinValue | 1 | 8.0 | | |
+-----------------------+-------+-------------+---------+---------+
| IPv4 | 2 | 8.0 | | |
+-----------------------+-------+-------------+---------+---------+
| IPv6 | 3 | 8.0 | | |
+-----------------------+-------+-------------+---------+---------+
| AddressFamilyMaxValue | 4 | 8.0 | | |
+-----------------------+-------+-------------+---------+---------+
Table 9 +=======+=======================+=============+=========+=========+
| Value | Name | Min. Schema | Max. | Comment |
| | | Version | Schema | |
| | | | Version | |
+=======+=======================+=============+=========+=========+
| 0 | Illegal | 8.0 | | |
+-------+-----------------------+-------------+---------+---------+
| 1 | AddressFamilyMinValue | 8.0 | | |
+-------+-----------------------+-------------+---------+---------+
| 2 | IPv4 | 8.0 | | |
+-------+-----------------------+-------------+---------+---------+
| 3 | IPv6 | 8.0 | | |
+-------+-----------------------+-------------+---------+---------+
| 4 | AddressFamilyMaxValue | 8.0 | | |
+-------+-----------------------+-------------+---------+---------+
10.3.3. Registry RIFT/common/HierarchyIndications Table 9: Address Family Type
The name of the registry should be RIFTCommonHierarchyIndications. 10.3.3. RIFTCommonHierarchyIndications Registry
Flags indicating node configuration in case of ZTP. This registry has the following initial values.
+====================================+=====+=======+=======+=======+ +====================================+=====+=======+=======+=======+
|Name |Value| Min.| Max.|Comment| |Name |Value|Min. |Max. |Comment|
| | | Schema| Schema| | | | |Schema |Schema | |
| | |Version|Version| | | | |Version|Version| |
+====================================+=====+=======+=======+=======+ +====================================+=====+=======+=======+=======+
|leaf_only | 0| 8.0| | | |leaf_only |0 |8.0 | | |
+------------------------------------+-----+-------+-------+-------+ +------------------------------------+-----+-------+-------+-------+
|leaf_only_and_leaf_2_leaf_procedures| 1| 8.0| | | |leaf_only_and_leaf_2_leaf_procedures|1 |8.0 | | |
+------------------------------------+-----+-------+-------+-------+ +------------------------------------+-----+-------+-------+-------+
|top_of_fabric | 2| 8.0| | | |top_of_fabric |2 |8.0 | | |
+------------------------------------+-----+-------+-------+-------+ +------------------------------------+-----+-------+-------+-------+
Table 10 Table 10: Flags Indicating Node Configuration in Case of ZTP
10.3.4. Registry RIFT/common/IEEE802_1ASTimeStampType 10.3.4. RIFTCommonIEEE8021ASTimeStampType Registry
The name of the registry should be RIFTCommonIEEE8021ASTimeStampType. This registry has the following initial values.
Timestamp per IEEE 802.1AS, all values MUST be interpreted in The timestamp is per IEEE 802.1AS; all values MUST be interpreted in
implementation as unsigned. implementation as unsigned.
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| AS_sec | 1 | 8.0 | | | | AS_sec | 1 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| AS_nsec | 2 | 8.0 | | | | AS_nsec | 2 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
Table 11 Table 11
10.3.5. Registry RIFT/common/IPAddressType 10.3.5. RIFTCommonIPAddressType Registry
The name of the registry should be RIFTCommonIPAddressType.
IP address type. This registry has the following initial values.
+=============+=======+=====================+=============+=========+ +=============+=======+=====================+=============+=========+
| Name | Value | Min. Schema | Max. Schema | Comment | | Name | Value | Min. Schema | Max. Schema | Comment |
| | | Version | Version | | | | | Version | Version | |
+=============+=======+=====================+=============+=========+ +=============+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+-------------+-------+---------------------+-------------+---------+ +-------------+-------+---------------------+-------------+---------+
| ipv4address | 1 | 8.0 | | Content | | ipv4address | 1 | 8.0 | | Content |
| | | | | is ipv4 | | | | | | is IPv4 |
+-------------+-------+---------------------+-------------+---------+ +-------------+-------+---------------------+-------------+---------+
| ipv6address | 2 | 8.0 | | Content | | ipv6address | 2 | 8.0 | | Content |
| | | | | is ipv6 | | | | | | is IPv6 |
+-------------+-------+---------------------+-------------+---------+ +-------------+-------+---------------------+-------------+---------+
Table 12 Table 12: IP Address Type
10.3.6. Registry RIFT/common/IPPrefixType
The name of the registry should be RIFTCommonIPPrefixType. 10.3.6. RIFTCommonIPPrefixType Registry
Prefix advertisement. This registry has the following initial values.
@note: for interface addresses the protocol can propagate the address Note: For interface addresses, the protocol can propagate the address
part beyond the subnet mask and on reachability computation that has part beyond the subnet mask and on reachability computation that has
to be normalized. The non-significant bits can be used for to be normalized. The non-significant bits can be used for
operational purposes. operational purposes.
+============+=======+=====================+=============+=========+ +============+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+============+=======+=====================+=============+=========+ +============+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+------------+-------+---------------------+-------------+---------+ +------------+-------+---------------------+-------------+---------+
| ipv4prefix | 1 | 8.0 | | | | ipv4prefix | 1 | 8.0 | | |
+------------+-------+---------------------+-------------+---------+ +------------+-------+---------------------+-------------+---------+
| ipv6prefix | 2 | 8.0 | | | | ipv6prefix | 2 | 8.0 | | |
+------------+-------+---------------------+-------------+---------+ +------------+-------+---------------------+-------------+---------+
Table 13 Table 13: Prefix Advertisement
10.3.7. Registry RIFT/common/IPv4PrefixType
The name of the registry should be RIFTCommonIPv4PrefixType. 10.3.7. RIFTCommonIPv4PrefixType Registry
IPv4 prefix type. This registry has the following initial values.
+===========+=======+=====================+=============+=========+ +===========+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+===========+=======+=====================+=============+=========+ +===========+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+-----------+-------+---------------------+-------------+---------+ +-----------+-------+---------------------+-------------+---------+
| address | 1 | 8.0 | | | | address | 1 | 8.0 | | |
+-----------+-------+---------------------+-------------+---------+ +-----------+-------+---------------------+-------------+---------+
| prefixlen | 2 | 8.0 | | | | prefixlen | 2 | 8.0 | | |
+-----------+-------+---------------------+-------------+---------+ +-----------+-------+---------------------+-------------+---------+
Table 14 Table 14: IPv4 Prefix Type
10.3.8. Registry RIFT/common/IPv6PrefixType
The name of the registry should be RIFTCommonIPv6PrefixType. 10.3.8. RIFTCommonIPv6PrefixType Registry
IPv6 prefix type. This registry has the following initial values.
+===========+=======+=====================+=============+=========+ +===========+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+===========+=======+=====================+=============+=========+ +===========+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+-----------+-------+---------------------+-------------+---------+ +-----------+-------+---------------------+-------------+---------+
| address | 1 | 8.0 | | | | address | 1 | 8.0 | | |
+-----------+-------+---------------------+-------------+---------+ +-----------+-------+---------------------+-------------+---------+
| prefixlen | 2 | 8.0 | | | | prefixlen | 2 | 8.0 | | |
+-----------+-------+---------------------+-------------+---------+ +-----------+-------+---------------------+-------------+---------+
Table 15 Table 15: IPv6 Prefix Type
10.3.9. Registry RIFT/common/KVTypes 10.3.9. RIFTCommonKVTypes Registry
The name of the registry should be RIFTCommonKVTypes. This registry has the following initial values.
+==============+=======+=============+=============+=========+ +==============+=======+=============+=============+=========+
| Name | Value | Min. Schema | Max. Schema | Comment | | Name | Value | Min. Schema | Max. Schema | Comment |
| | | Version | Version | | | | | Version | Version | |
+==============+=======+=============+=============+=========+ +==============+=======+=============+=============+=========+
| Experimental | 1 | 8.0 | | | | Unassigned | 0 | | | |
+--------------+-------+-------------+-------------+---------+ +--------------+-------+-------------+-------------+---------+
| WellKnown | 2 | 8.0 | | | | Experimental | 1 | 8.0 | | |
+--------------+-------+-------------+-------------+---------+ +--------------+-------+-------------+-------------+---------+
| OUI | 3 | 8.0 | | | | WellKnown | 2 | 8.0 | | |
+--------------+-------+-------------+-------------+---------+
| OUI | 3 | 8.0 | | |
+--------------+-------+-------------+-------------+---------+ +--------------+-------+-------------+-------------+---------+
Table 16 Table 16
10.3.10. Registry RIFT/common/PrefixSequenceType 10.3.10. RIFTCommonPrefixSequenceType Registry
The name of the registry should be RIFTCommonPrefixSequenceType. This registry has the following initial values.
Sequence of a prefix in case of move. +===============+=======+=========+==========+===================+
| Name | Value | Min. | Max. | Comment |
| | | Schema | Schema | |
| | | Version | Version | |
+===============+=======+=========+==========+===================+
| Reserved | 0 | 8.0 | All | |
| | | | Versions | |
+---------------+-------+---------+----------+-------------------+
| timestamp | 1 | 8.0 | | |
+---------------+-------+---------+----------+-------------------+
| transactionid | 2 | 8.0 | | Transaction ID |
| | | | | set by client in, |
| | | | | e.g., 6LoWPAN. |
+---------------+-------+---------+----------+-------------------+
+===============+=======+=============+==========+==================+ Table 17: Sequence of a Prefix in Case of Move
| Name | Value | Min. | Max. | Comment |
| | | Schema | Schema | |
| | | Version | Version | |
+===============+=======+=============+==========+==================+
| Reserved | 0 | 8.0 | All | |
| | | | Versions | |
+---------------+-------+-------------+----------+------------------+
| timestamp | 1 | 8.0 | | |
+---------------+-------+-------------+----------+------------------+
| transactionid | 2 | 8.0 | | Transaction id |
| | | | | set by client in |
| | | | | e.g. in 6lowpan. |
+---------------+-------+-------------+----------+------------------+
Table 17 10.3.11. RIFTCommonRouteType Registry
10.3.11. Registry RIFT/common/RouteType This registry has the following initial values.
The name of the registry should be RIFTCommonRouteType. Note: The only purpose of these values is to introduce an ordering,
whereas an implementation can internally choose any other values as
long the ordering is preserved.
RIFT route types. @note: The only purpose of those values is to
introduce an ordering whereas an implementation can choose internally
any other values as long the ordering is preserved
+=====================+=======+=============+=============+=========+ +=====================+=======+=============+=============+=========+
| Name | Value | Min. Schema | Max. | Comment | | Name | Value | Min. Schema | Max. | Comment |
| | | Version | Schema | | | | | Version | Schema | |
| | | | Version | | | | | | Version | |
+=====================+=======+=============+=============+=========+ +=====================+=======+=============+=============+=========+
| Illegal | 0 | 8.0 | | | | Illegal | 0 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| RouteTypeMinValue | 1 | 8.0 | | | | RouteTypeMinValue | 1 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| Discard | 2 | 8.0 | | | | Discard | 2 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| LocalPrefix | 3 | 8.0 | | | | LocalPrefix | 3 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| SouthPGPPrefix | 4 | 8.0 | | | | SouthPGPPrefix | 4 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| NorthPGPPrefix | 5 | 8.0 | | | | NorthPGPPrefix | 5 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| NorthPrefix | 6 | 8.0 | | | | NorthPrefix | 6 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| NorthExternalPrefix | 7 | 8.0 | | | | NorthExternalPrefix | 7 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| SouthPrefix | 8 | 8.0 | | | | SouthPrefix | 8 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| SouthExternalPrefix | 9 | 8.0 | | | | SouthExternalPrefix | 9 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| NegativeSouthPrefix | 10 | 8.0 | | | | NegativeSouthPrefix | 10 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
| RouteTypeMaxValue | 11 | 8.0 | | | | RouteTypeMaxValue | 11 | 8.0 | | |
+---------------------+-------+-------------+-------------+---------+ +---------------------+-------+-------------+-------------+---------+
Table 18 Table 18: RIFT Route Types
10.3.12. Registry RIFT/common/TIETypeType
The name of the registry should be RIFTCommonTIETypeType.
Type of TIE. 10.3.12. RIFTCommonTIETypeType Registry
+===========================================+=====+=======+=======+=======+ This registry has the following initial values.
|Name |Value| Min.| Max.|Comment|
| | | Schema| Schema| |
| | |Version|Version| |
+===========================================+=====+=======+=======+=======+
|Illegal | 0| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|TIETypeMinValue | 1| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|NodeTIEType | 2| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|PrefixTIEType | 3| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|PositiveDisaggregationPrefixTIEType | 4| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|NegativeDisaggregationPrefixTIEType | 5| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|PGPrefixTIEType | 6| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|KeyValueTIEType | 7| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|ExternalPrefixTIEType | 8| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|PositiveExternalDisaggregationPrefixTIEType| 9| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
|TIETypeMaxValue | 10| 8.0| | |
+-------------------------------------------+-----+-------+-------+-------+
Table 19 +===================================+=====+=======+=======+=======+
|Name |Value|Min. |Max. |Comment|
| | |Schema |Schema | |
| | |Version|Version| |
+===================================+=====+=======+=======+=======+
|Illegal |0 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
|TIETypeMinValue |1 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
|NodeTIEType |2 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
|PrefixTIEType |3 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
|PositiveDisaggregationPrefixTIEType|4 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
|NegativeDisaggregationPrefixTIEType|5 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
|PGPrefixTIEType |6 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
|KeyValueTIEType |7 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
|ExternalPrefixTIEType |8 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
|PositiveExternalDisaggregation |9 |8.0 | | |
|PrefixTIEType | | | | |
+-----------------------------------+-----+-------+-------+-------+
|TIETypeMaxValue |10 |8.0 | | |
+-----------------------------------+-----+-------+-------+-------+
10.3.13. Registry RIFT/common/TieDirectionType Table 19: Type of TIE
The name of the registry should be RIFTCommonTieDirectionType. 10.3.13. RIFTCommonTieDirectionType Registry
Direction of TIEs. This registry has the following initial values.
+===================+=======+=============+=============+=========+ +===================+=======+=============+=============+=========+
| Name | Value | Min. Schema | Max. Schema | Comment | | Name | Value | Min. Schema | Max. Schema | Comment |
| | | Version | Version | | | | | Version | Version | |
+===================+=======+=============+=============+=========+ +===================+=======+=============+=============+=========+
| Illegal | 0 | 8.0 | | | | Illegal | 0 | 8.0 | | |
+-------------------+-------+-------------+-------------+---------+ +-------------------+-------+-------------+-------------+---------+
| South | 1 | 8.0 | | | | South | 1 | 8.0 | | |
+-------------------+-------+-------------+-------------+---------+ +-------------------+-------+-------------+-------------+---------+
| North | 2 | 8.0 | | | | North | 2 | 8.0 | | |
+-------------------+-------+-------------+-------------+---------+ +-------------------+-------+-------------+-------------+---------+
| DirectionMaxValue | 3 | 8.0 | | | | DirectionMaxValue | 3 | 8.0 | | |
+-------------------+-------+-------------+-------------+---------+ +-------------------+-------+-------------+-------------+---------+
Table 20 Table 20: Direction of TIEs
10.3.14. Registry RIFT/encoding/Community
The name of the registry should be RIFTEncodingCommunity. 10.3.14. RIFTEncodingCommunity Registry
Prefix community. This registry has the following initial values.
+==========+=======+=====================+=============+============+ +==========+=======+=====================+=============+============+
| Name | Value | Min. Schema | Max. Schema | Comment | | Name | Value | Min. Schema | Max. Schema | Comment |
| | | Version | Version | | | | | Version | Version | |
+==========+=======+=====================+=============+============+ +==========+=======+=====================+=============+============+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------+-------+---------------------+-------------+------------+ +----------+-------+---------------------+-------------+------------+
| top | 1 | 8.0 | | Higher | | top | 1 | 8.0 | | Higher |
| | | | | order bits | | | | | | order bits |
+----------+-------+---------------------+-------------+------------+ +----------+-------+---------------------+-------------+------------+
| bottom | 2 | 8.0 | | Lower | | bottom | 2 | 8.0 | | Lower |
| | | | | order bits | | | | | | order bits |
+----------+-------+---------------------+-------------+------------+ +----------+-------+---------------------+-------------+------------+
Table 21 Table 21: Prefix Community
10.3.15. Registry RIFT/encoding/KeyValueTIEElement
The name of the registry should be RIFTEncodingKeyValueTIEElement. 10.3.15. RIFTEncodingKeyValueTIEElement Registry
Generic key value pairs. This registry has the following initial values.
+===========+=======+=====================+=============+=========+ +===========+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+===========+=======+=====================+=============+=========+ +===========+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+-----------+-------+---------------------+-------------+---------+ +-----------+-------+---------------------+-------------+---------+
| keyvalues | 1 | 8.0 | | | | keyvalues | 1 | 8.0 | | |
+-----------+-------+---------------------+-------------+---------+ +-----------+-------+---------------------+-------------+---------+
Table 22 Table 22: Generic Key Value Pairs
10.3.16. Registry RIFT/encoding/KeyValueTIEElementContent
The name of the registry should be 10.3.16. RIFTEncodingKeyValueTIEElementContent Registry
RIFTEncodingKeyValueTIEElementContent.
Defines the targeted nodes and the value carried. This registry has the following initial values. It defines the
targeted nodes and the value carried.
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| targets | 1 | 8.0 | | | | targets | 1 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| value | 2 | 8.0 | | | | value | 2 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
Table 23 Table 23
10.3.17. Registry RIFT/encoding/LIEPacket 10.3.17. RIFTEncodingLIEPacket Registry
The name of the registry should be RIFTEncodingLIEPacket.
RIFT LIE Packet.
@note: this node's level is already included on the packet header This registry has the following initial values.
+=============================+=====+=======+========+=============+ Note: This node's level is already included on the packet header.
| Name |Value| Min.| Max.|Comment |
| | | Schema| Schema| |
| | |Version| Version| |
+=============================+=====+=======+========+=============+
| Reserved | 0| 8.0| All| |
| | | |Versions| |
+-----------------------------+-----+-------+--------+-------------+
| name | 1| 8.0| | Node or|
| | | | | adjacency|
| | | | | name.|
+-----------------------------+-----+-------+--------+-------------+
| local_id | 2| 8.0| | Local link|
| | | | | id.|
+-----------------------------+-----+-------+--------+-------------+
| flood_port | 3| 8.0| | Udp port to|
| | | | | which we can|
| | | | | receive|
| | | | |flooded ties.|
+-----------------------------+-----+-------+--------+-------------+
| link_mtu_size | 4| 8.0| | Layer 2 mtu,|
| | | | | used to|
| | | | | discover|
| | | | | mismatch.|
+-----------------------------+-----+-------+--------+-------------+
| link_bandwidth | 5| 8.0| | Local link|
| | | | | bandwidth on|
| | | | | the|
| | | | | interface.|
+-----------------------------+-----+-------+--------+-------------+
| neighbor | 6| 8.0| | Reflects the|
| | | | |neighbor once|
| | | | | received to|
| | | | |provide 3-way|
| | | | |connectivity.|
+-----------------------------+-----+-------+--------+-------------+
| pod | 7| 8.0| | Node's pod.|
+-----------------------------+-----+-------+--------+-------------+
| node_capabilities | 10| 8.0| | Node|
| | | | | capabilities|
| | | | | supported.|
+-----------------------------+-----+-------+--------+-------------+
| link_capabilities | 11| 8.0| | Capabilities|
| | | | |of this link.|
+-----------------------------+-----+-------+--------+-------------+
| holdtime | 12| 8.0| | Required|
| | | | | holdtime of|
| | | | | the|
| | | | | adjacency,|
| | | | | i.e. for how|
| | | | |long a period|
| | | | | should|
| | | | | adjacency be|
| | | | | kept up|
| | | | |without valid|
| | | | | lie|
| | | | | reception.|
+-----------------------------+-----+-------+--------+-------------+
| label | 13| 8.0| | Optional,|
| | | | | unsolicited,|
| | | | | downstream|
| | | | | assigned|
| | | | | locally|
| | | | | significant|
| | | | | label value|
| | | | | for the|
| | | | | adjacency.|
+-----------------------------+-----+-------+--------+-------------+
| not_a_ztp_offer | 21| 8.0| | Indicates|
| | | | | that the|
| | | | | level on the|
| | | | | lie must not|
| | | | | be used to|
| | | | | derive a ztp|
| | | | | level by the|
| | | | | receiving|
| | | | | node.|
+-----------------------------+-----+-------+--------+-------------+
| you_are_flood_repeater | 22| 8.0| | Indicates to|
| | | | | northbound|
| | | | |neighbor that|
| | | | | it should be|
| | | | | reflooding|
| | | | |ties received|
| | | | | from this|
| | | | | node to|
| | | | |achieve flood|
| | | | |reduction and|
| | | | |balancing for|
| | | | | northbound|
| | | | | flooding.|
+-----------------------------+-----+-------+--------+-------------+
| you_are_sending_too_quickly | 23| 8.0| | Indicates to|
| | | | | neighbor to|
| | | | | flood node|
| | | | |ties only and|
| | | | |slow down all|
| | | | | other ties.|
| | | | | ignored when|
| | | | |received from|
| | | | | southbound|
| | | | | neighbor.|
+-----------------------------+-----+-------+--------+-------------+
| instance_name | 24| 8.0| |Instance name|
| | | | | in case|
| | | | |multiple rift|
| | | | | instances|
| | | | | running on|
| | | | | same|
| | | | | interface.|
+-----------------------------+-----+-------+--------+-------------+
| fabric_id | 35| 8.0| | It provides|
| | | | | the optional|
| | | | | id of the|
| | | | | fabric|
| | | | | configured.|
| | | | | this must|
| | | | | match the|
| | | | | information|
| | | | |advertised on|
| | | | | the node|
| | | | | element.|
+-----------------------------+-----+-------+--------+-------------+
Table 24 +=============================+=====+=======+========+==============+
| Name |Value|Min. |Max. |Comment |
| | |Schema |Schema | |
| | |Version|Version | |
+=============================+=====+=======+========+==============+
| Reserved |0 |8.0 |All | |
| | | |Versions| |
+-----------------------------+-----+-------+--------+--------------+
| name |1 |8.0 | |Node or |
| | | | |adjacency |
| | | | |name. |
+-----------------------------+-----+-------+--------+--------------+
| local_id |2 |8.0 | |Local link |
| | | | |ID. |
+-----------------------------+-----+-------+--------+--------------+
| flood_port |3 |8.0 | |UDP port to |
| | | | |which we can |
| | | | |receive |
| | | | |flooded ties. |
+-----------------------------+-----+-------+--------+--------------+
| link_mtu_size |4 |8.0 | |Layer 2 MTU, |
| | | | |used to |
| | | | |discover |
| | | | |mismatch. |
+-----------------------------+-----+-------+--------+--------------+
| link_bandwidth |5 |8.0 | |Local link |
| | | | |bandwidth on |
| | | | |the |
| | | | |interface. |
+-----------------------------+-----+-------+--------+--------------+
| neighbor |6 |8.0 | |Reflects the |
| | | | |neighbor once |
| | | | |received to |
| | | | |provide 3-way |
| | | | |connectivity. |
+-----------------------------+-----+-------+--------+--------------+
| pod |7 |8.0 | |Node's PoD. |
+-----------------------------+-----+-------+--------+--------------+
| node_capabilities |10 |8.0 | |Node |
| | | | |capabilities |
| | | | |supported. |
+-----------------------------+-----+-------+--------+--------------+
| link_capabilities |11 |8.0 | |Capabilities |
| | | | |of this link. |
+-----------------------------+-----+-------+--------+--------------+
| holdtime |12 |8.0 | |Required |
| | | | |holdtime of |
| | | | |the |
| | | | |adjacency, |
| | | | |i.e., for how |
| | | | |long a period |
| | | | |adjacency |
| | | | |should be |
| | | | |kept up |
| | | | |without valid |
| | | | |LIE |
| | | | |reception. |
+-----------------------------+-----+-------+--------+--------------+
| label |13 |8.0 | |Optional, |
| | | | |unsolicited, |
| | | | |downstream |
| | | | |assigned |
| | | | |locally |
| | | | |significant |
| | | | |label value |
| | | | |for the |
| | | | |adjacency. |
+-----------------------------+-----+-------+--------+--------------+
| not_a_ztp_offer |21 |8.0 | |Indicates |
| | | | |that the |
| | | | |level on the |
| | | | |lie must not |
| | | | |be used to |
| | | | |derive a ZTP |
| | | | |level by the |
| | | | |receiving |
| | | | |node. |
+-----------------------------+-----+-------+--------+--------------+
| you_are_flood_repeater |22 |8.0 | |Indicates to |
| | | | |the |
| | | | |northbound |
| | | | |neighbor that |
| | | | |it should be |
| | | | |reflooding |
| | | | |ties received |
| | | | |from this |
| | | | |node to |
| | | | |achieve flood |
| | | | |reduction and |
| | | | |balancing for |
| | | | |northbound |
| | | | |flooding. |
+-----------------------------+-----+-------+--------+--------------+
| you_are_sending_too_quickly |23 |8.0 | |Indicates to |
| | | | |the neighbor |
| | | | |to flood node |
| | | | |ties only and |
| | | | |slow down all |
| | | | |other ties. |
| | | | |Ignored when |
| | | | |received from |
| | | | |the |
| | | | |southbound |
| | | | |neighbor. |
+-----------------------------+-----+-------+--------+--------------+
| instance_name |24 |8.0 | |Instance name |
| | | | |in case |
| | | | |multiple rift |
| | | | |instances |
| | | | |running on |
| | | | |same |
| | | | |interface. |
+-----------------------------+-----+-------+--------+--------------+
| fabric_id |35 |8.0 | |It provides |
| | | | |the optional |
| | | | |ID of the |
| | | | |fabric |
| | | | |configured. |
| | | | |This must |
| | | | |match the |
| | | | |information |
| | | | |advertised on |
| | | | |the node |
| | | | |element. |
+-----------------------------+-----+-------+--------+--------------+
10.3.18. Registry RIFT/encoding/LinkCapabilities Table 24: RIFT LIE Packet
The name of the registry should be RIFTEncodingLinkCapabilities. 10.3.18. RIFTEncodingLinkCapabilities Registry
Link capabilities. This registry has the following initial values.
+=========================+=====+=========+==========+==============+ +=========================+=====+=========+==========+==============+
| Name |Value| Min. | Max. | Comment | | Name |Value| Min. | Max. | Comment |
| | | Schema | Schema | | | | | Schema | Schema | |
| | | Version | Version | | | | | Version | Version | |
+=========================+=====+=========+==========+==============+ +=========================+=====+=========+==========+==============+
| Reserved | 0| 8.0 | All | | | Reserved |0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+-------------------------+-----+---------+----------+--------------+ +-------------------------+-----+---------+----------+--------------+
| bfd | 1| 8.0 | | Indicates | | bfd |1 | 8.0 | | Indicates |
| | | | | that the | | | | | | that the |
| | | | | link is | | | | | | link is |
| | | | | supporting | | | | | | supporting |
| | | | | bfd. | | | | | | BFD. |
+-------------------------+-----+---------+----------+--------------+ +-------------------------+-----+---------+----------+--------------+
| ipv4_forwarding_capable | 2| 8.0 | | Indicates | | ipv4_forwarding_capable |2 | 8.0 | | Indicates |
| | | | | whether the | | | | | | whether the |
| | | | | interface | | | | | | interface |
| | | | | will | | | | | | will |
| | | | | support | | | | | | support |
| | | | | ipv4 | | | | | | IPv4 |
| | | | | forwarding. | | | | | | forwarding. |
+-------------------------+-----+---------+----------+--------------+ +-------------------------+-----+---------+----------+--------------+
Table 25 Table 25: Link Capabilities
10.3.19. Registry RIFT/encoding/LinkIDPair
The name of the registry should be RIFTEncodingLinkIDPair. 10.3.19. RIFTEncodingLinkIDPair Registry
LinkID pair describes one of parallel links between two nodes. The LinkID pair describes one of the parallel links between two
nodes.
+============================+=====+=======+========+===============+ This registry has the following initial values.
| Name |Value| Min.| Max.| Comment |
| | | Schema| Schema| |
| | |Version| Version| |
+============================+=====+=======+========+===============+
| Reserved | 0| 8.0| All| |
| | | |Versions| |
+----------------------------+-----+-------+--------+---------------+
| local_id | 1| 8.0| | Node-wide |
| | | | | unique value |
| | | | | for the |
| | | | | local link. |
+----------------------------+-----+-------+--------+---------------+
| remote_id | 2| 8.0| | Received |
| | | | | remote link |
| | | | | id for this |
| | | | | link. |
+----------------------------+-----+-------+--------+---------------+
| platform_interface_index | 10| 8.0| | Describes |
| | | | | the local |
| | | | | interface |
| | | | | index of the |
| | | | | link. |
+----------------------------+-----+-------+--------+---------------+
| platform_interface_name | 11| 8.0| | Describes |
| | | | | the local |
| | | | | interface |
| | | | | name. |
+----------------------------+-----+-------+--------+---------------+
| trusted_outer_security_key | 12| 8.0| | Indicates |
| | | | | whether the |
| | | | | link is |
| | | | | secured, |
| | | | | i.e. |
| | | | | protected by |
| | | | | outer key, |
| | | | | absence of |
| | | | | this element |
| | | | | means no |
| | | | | indication, |
| | | | | undefined |
| | | | | outer key |
| | | | | means not |
| | | | | secured. |
+----------------------------+-----+-------+--------+---------------+
| bfd_up | 13| 8.0| | Indicates |
| | | | | whether the |
| | | | | link is |
| | | | | protected by |
| | | | | established |
| | | | | bfd session. |
+----------------------------+-----+-------+--------+---------------+
| address_families | 14| 8.0| | Optional |
| | | | | indication |
| | | | | which |
| | | | | address |
| | | | | families are |
| | | | | up on the |
| | | | | interface. |
+----------------------------+-----+-------+--------+---------------+
Table 26 +============================+=====+=======+========+==============+
| Name |Value|Min. |Max. | Comment |
| | |Schema |Schema | |
| | |Version|Version | |
+============================+=====+=======+========+==============+
| Reserved |0 |8.0 |All | |
| | | |Versions| |
+----------------------------+-----+-------+--------+--------------+
| local_id |1 |8.0 | | Node-wide |
| | | | | unique value |
| | | | | for the |
| | | | | local link. |
+----------------------------+-----+-------+--------+--------------+
| remote_id |2 |8.0 | | Received the |
| | | | | remote link |
| | | | | ID for this |
| | | | | link. |
+----------------------------+-----+-------+--------+--------------+
| platform_interface_index |10 |8.0 | | Describes |
| | | | | the local |
| | | | | interface |
| | | | | index of the |
| | | | | link. |
+----------------------------+-----+-------+--------+--------------+
| platform_interface_name |11 |8.0 | | Describes |
| | | | | the local |
| | | | | interface |
| | | | | name. |
+----------------------------+-----+-------+--------+--------------+
| trusted_outer_security_key |12 |8.0 | | Indicates |
| | | | | whether the |
| | | | | link is |
| | | | | secured, |
| | | | | i.e., |
| | | | | protected by |
| | | | | outer key, |
| | | | | absence of |
| | | | | this element |
| | | | | means no |
| | | | | indication, |
| | | | | undefined |
| | | | | outer key |
| | | | | means not |
| | | | | secured. |
+----------------------------+-----+-------+--------+--------------+
| bfd_up |13 |8.0 | | Indicates |
| | | | | whether the |
| | | | | link is |
| | | | | protected by |
| | | | | an |
| | | | | established |
| | | | | BFD session. |
+----------------------------+-----+-------+--------+--------------+
| address_families |14 |8.0 | | Optional |
| | | | | indication |
| | | | | that address |
| | | | | families are |
| | | | | up on the |
| | | | | interface. |
+----------------------------+-----+-------+--------+--------------+
10.3.20. Registry RIFT/encoding/Neighbor Table 26
The name of the registry should be RIFTEncodingNeighbor. 10.3.20. RIFTEncodingNeighbor Registry
Neighbor structure. This registry has the following initial values.
+============+=======+=============+=============+=================+ +============+=======+=============+=============+=================+
| Name | Value | Min. Schema | Max. Schema | Comment | | Name | Value | Min. Schema | Max. Schema | Comment |
| | | Version | Version | | | | | Version | Version | |
+============+=======+=============+=============+=================+ +============+=======+=============+=============+=================+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+------------+-------+-------------+-------------+-----------------+ +------------+-------+-------------+-------------+-----------------+
| originator | 1 | 8.0 | | System id of | | originator | 1 | 8.0 | | System ID of |
| | | | | the originator. | | | | | | the originator. |
+------------+-------+-------------+-------------+-----------------+ +------------+-------+-------------+-------------+-----------------+
| remote_id | 2 | 8.0 | | Id of remote | | remote_id | 2 | 8.0 | | ID of remote |
| | | | | side of the | | | | | | side of the |
| | | | | link. | | | | | | link. |
+------------+-------+-------------+-------------+-----------------+ +------------+-------+-------------+-------------+-----------------+
Table 27 Table 27: Neighbor Structure
10.3.21. Registry RIFT/encoding/NodeCapabilities
The name of the registry should be RIFTEncodingNodeCapabilities.
Capabilities the node supports. 10.3.21. RIFTEncodingNodeCapabilities Registry
+========================+=====+=======+==========+=================+ This registry has the following initial values.
| Name |Value| Min.| Max. | Comment |
| | | Schema| Schema | |
| | |Version| Version | |
+========================+=====+=======+==========+=================+
| Reserved | 0| 8.0| All | |
| | | | Versions | |
+------------------------+-----+-------+----------+-----------------+
| protocol_minor_version | 1| 8.0| | Must advertise |
| | | | | supported |
| | | | | minor version |
| | | | | dialect that |
| | | | | way. |
+------------------------+-----+-------+----------+-----------------+
| flood_reduction | 2| 8.0| | Indicates that |
| | | | | node supports |
| | | | | flood |
| | | | | reduction. |
+------------------------+-----+-------+----------+-----------------+
| hierarchy_indications | 3| 8.0| | Indicates |
| | | | | place in |
| | | | | hierarchy, |
| | | | | i.e. top-of- |
| | | | | fabric or leaf |
| | | | | only (in ztp) |
| | | | | or support for |
| | | | | leaf-2-leaf |
| | | | | procedures. |
+------------------------+-----+-------+----------+-----------------+
Table 28 +========================+=====+=========+==========+==============+
| Name |Value| Min. | Max. | Comment |
| | | Schema | Schema | |
| | | Version | Version | |
+========================+=====+=========+==========+==============+
| Reserved |0 | 8.0 | All | |
| | | | Versions | |
+------------------------+-----+---------+----------+--------------+
| protocol_minor_version |1 | 8.0 | | Must |
| | | | | advertise |
| | | | | supported |
| | | | | minor |
| | | | | version |
| | | | | dialect that |
| | | | | way. |
+------------------------+-----+---------+----------+--------------+
| flood_reduction |2 | 8.0 | | Indicates |
| | | | | that node |
| | | | | supports |
| | | | | flood |
| | | | | reduction. |
+------------------------+-----+---------+----------+--------------+
| hierarchy_indications |3 | 8.0 | | Indicates |
| | | | | place in |
| | | | | hierarchy, |
| | | | | i.e., top of |
| | | | | fabric or |
| | | | | leaf only |
| | | | | (in ZTP) or |
| | | | | support for |
| | | | | leaf-to-leaf |
| | | | | procedures. |
+------------------------+-----+---------+----------+--------------+
10.3.22. Registry RIFT/encoding/NodeFlags Table 28: Capabilities the Node Supports
The name of the registry should be RIFTEncodingNodeFlags. 10.3.22. RIFTEncodingNodeFlags Registry
Indication flags of the node. This registry has the following initial values.
+==========+=======+=========+==========+===========================+ +==========+=======+=========+==========+===========================+
| Name | Value | Min. | Max. | Comment | | Name | Value | Min. | Max. | Comment |
| | | Schema | Schema | | | | | Schema | Schema | |
| | | Version | Version | | | | | Version | Version | |
+==========+=======+=========+==========+===========================+ +==========+=======+=========+==========+===========================+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------+-------+---------+----------+---------------------------+ +----------+-------+---------+----------+---------------------------+
| overload | 1 | 8.0 | | Indicates that node | | overload | 1 | 8.0 | | Indicates that node |
| | | | | is in overload, do | | | | | | is in overload; do |
| | | | | not transit traffic | | | | | | not transit traffic |
| | | | | through it. | | | | | | through it. |
+----------+-------+---------+----------+---------------------------+ +----------+-------+---------+----------+---------------------------+
Table 29 Table 29: Indication Flags of the Node
10.3.23. Registry RIFT/encoding/NodeNeighborsTIEElement
The name of the registry should be 10.3.23. RIFTEncodingNodeNeighborsTIEElement Registry
RIFTEncodingNodeNeighborsTIEElement.
neighbor of a node This registry has the following initial values.
+===========+=======+=========+==========+==========================+
| Name | Value | Min. | Max. | Comment |
| | | Schema | Schema | |
| | | Version | Version | |
+===========+=======+=========+==========+==========================+
| Reserved | 0 | 8.0 | All | |
| | | | Versions | |
+-----------+-------+---------+----------+--------------------------+
| level | 1 | 8.0 | | Level of neighbor. |
+-----------+-------+---------+----------+--------------------------+
| cost | 3 | 8.0 | | Cost to neighbor. |
| | | | | ignore anything |
| | | | | equal or larger than |
| | | | | `infinite_distance` |
| | | | | and equal to |
| | | | | `invalid_distance`. |
+-----------+-------+---------+----------+--------------------------+
| link_ids | 4 | 8.0 | | Carries description |
| | | | | of multiple parallel |
| | | | | links in a tie. |
+-----------+-------+---------+----------+--------------------------+
| bandwidth | 5 | 8.0 | | Total bandwith to |
| | | | | neighbor as sum of |
| | | | | all parallel links. |
+-----------+-------+---------+----------+--------------------------+
Table 30 +===========+=======+=========+==========+======================+
| Name | Value | Min. | Max. | Comment |
| | | Schema | Schema | |
| | | Version | Version | |
+===========+=======+=========+==========+======================+
| Reserved | 0 | 8.0 | All | |
| | | | Versions | |
+-----------+-------+---------+----------+----------------------+
| level | 1 | 8.0 | | Level of neighbor. |
+-----------+-------+---------+----------+----------------------+
| cost | 3 | 8.0 | | Cost to neighbor. |
| | | | | Ignore anything |
| | | | | equal or larger than |
| | | | | 'infinite_distance' |
| | | | | and equal to |
| | | | | 'invalid_distance'. |
+-----------+-------+---------+----------+----------------------+
| link_ids | 4 | 8.0 | | Carries description |
| | | | | of multiple parallel |
| | | | | links in a tie. |
+-----------+-------+---------+----------+----------------------+
| bandwidth | 5 | 8.0 | | Total bandwidth to |
| | | | | neighbor as sum of |
| | | | | all parallel links. |
+-----------+-------+---------+----------+----------------------+
10.3.24. Registry RIFT/encoding/NodeTIEElement Table 30: Neighbor of a Node
The name of the registry should be RIFTEncodingNodeTIEElement. 10.3.24. RIFTEncodingNodeTIEElement Registry
Description of a node. This registry has the following initial values.
+=================+=======+=========+==========+====================+ +=================+=======+=========+==========+====================+
| Name | Value | Min. | Max. | Comment | | Name | Value | Min. | Max. | Comment |
| | | Schema | Schema | | | | | Schema | Schema | |
| | | Version | Version | | | | | Version | Version | |
+=================+=======+=========+==========+====================+ +=================+=======+=========+==========+====================+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| level | 1 | 8.0 | | Level of the | | level | 1 | 8.0 | | Level of the |
| | | | | node. | | | | | | node. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| neighbors | 2 | 8.0 | | Node's neighbors. | | neighbors | 2 | 8.0 | | Node's neighbors. |
| | | | | multiple node | | | | | | Multiple node |
| | | | | ties can carry | | | | | | ties can carry |
| | | | | disjoint sets of | | | | | | disjoint sets of |
| | | | | neighbors. | | | | | | neighbors. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| capabilities | 3 | 8.0 | | Capabilities of | | capabilities | 3 | 8.0 | | Capabilities of |
| | | | | the node. | | | | | | the node. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| flags | 4 | 8.0 | | Flags of the | | flags | 4 | 8.0 | | Flags of the |
| | | | | node. | | | | | | node. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| name | 5 | 8.0 | | Optional node | | name | 5 | 8.0 | | Optional node |
| | | | | name for easier | | | | | | name for easier |
| | | | | operations. | | | | | | operations. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| pod | 6 | 8.0 | | Pod to which the | | pod | 6 | 8.0 | | Pod to which the |
| | | | | node belongs. | | | | | | node belongs. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| startup_time | 7 | 8.0 | | Optional startup | | startup_time | 7 | 8.0 | | Optional startup |
| | | | | time of the node | | | | | | time of the node. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| miscabled_links | 10 | 8.0 | | If any local | | miscabled_links | 10 | 8.0 | | If any local |
| | | | | links are | | | | | | links are |
| | | | | miscabled, this | | | | | | miscabled, this |
| | | | | indication is | | | | | | indication is |
| | | | | flooded. | | | | | | flooded. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| same_plane_tofs | 12 | 8.0 | | Tofs in the same | | same_plane_tofs | 12 | 8.0 | | ToFs in the same |
| | | | | plane. only | | | | | | plane. Only |
| | | | | carried by tof. | | | | | | carried by ToF. |
| | | | | multiple node | | | | | | Multiple node |
| | | | | ties can carry | | | | | | ties can carry |
| | | | | disjoint sets of | | | | | | disjoint sets of |
| | | | | tofs which must | | | | | | ToFs that must be |
| | | | | be joined to form | | | | | | joined to form a |
| | | | | a single set. | | | | | | single set. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
| fabric_id | 20 | 8.0 | | It provides the | | fabric_id | 20 | 8.0 | | It provides the |
| | | | | optional id of | | | | | | optional ID of |
| | | | | the fabric | | | | | | the fabric |
| | | | | configured | | | | | | configured. |
+-----------------+-------+---------+----------+--------------------+ +-----------------+-------+---------+----------+--------------------+
Table 31 Table 31: Description of a Node
10.3.25. Registry RIFT/encoding/PacketContent
The name of the registry should be RIFTEncodingPacketContent. 10.3.25. RIFTEncodingPacketContent Registry
Content of a RIFT packet. This registry has the following initial values.
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| lie | 1 | 8.0 | | | | lie | 1 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| tide | 2 | 8.0 | | | | tide | 2 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| tire | 3 | 8.0 | | | | tire | 3 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| tie | 4 | 8.0 | | | | tie | 4 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
Table 32 Table 32: Content of a RIFT Packet
10.3.26. Registry RIFT/encoding/PacketHeader
The name of the registry should be RIFTEncodingPacketHeader. 10.3.26. RIFTEncodingPacketHeader Registry
Common RIFT packet header. This registry has the following initial values.
+===============+=======+=========+==========+===================+ +===============+=======+=========+==========+===================+
| Name | Value | Min. | Max. | Comment | | Name | Value | Min. | Max. | Comment |
| | | Schema | Schema | | | | | Schema | Schema | |
| | | Version | Version | | | | | Version | Version | |
+===============+=======+=========+==========+===================+ +===============+=======+=========+==========+===================+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+---------------+-------+---------+----------+-------------------+ +---------------+-------+---------+----------+-------------------+
| major_version | 1 | 8.0 | | Major version of | | major_version | 1 | 8.0 | | Major version of |
| | | | | protocol. | | | | | | protocol. |
+---------------+-------+---------+----------+-------------------+ +---------------+-------+---------+----------+-------------------+
| minor_version | 2 | 8.0 | | Minor version of | | minor_version | 2 | 8.0 | | Minor version of |
| | | | | protocol. | | | | | | protocol. |
+---------------+-------+---------+----------+-------------------+ +---------------+-------+---------+----------+-------------------+
| sender | 3 | 8.0 | | Node sending the | | sender | 3 | 8.0 | | Node sending the |
| | | | | packet, in case | | | | | | packet, in case |
| | | | | of lie/tire/tide | | | | | | of LIE/TIRE/TIDE |
| | | | | also the | | | | | | also the |
| | | | | originator of it. | | | | | | originator of it. |
+---------------+-------+---------+----------+-------------------+ +---------------+-------+---------+----------+-------------------+
| level | 4 | 8.0 | | Level of the node | | level | 4 | 8.0 | | Level of the node |
| | | | | sending the | | | | | | sending the |
| | | | | packet, required | | | | | | packet, required |
| | | | | on everything | | | | | | on everything |
| | | | | except lies. lack | | | | | | except LIEs. |
| | | | | of presence on | | | | | | Lack of presence |
| | | | | lies indicates | | | | | | on LIEs indicates |
| | | | | undefined_level | | | | | | undefined_level |
| | | | | and is used in | | | | | | and is used in |
| | | | | ztp procedures. | | | | | | ZTP procedures. |
+---------------+-------+---------+----------+-------------------+ +---------------+-------+---------+----------+-------------------+
Table 33 Table 33: Common RIFT Packet Header
10.3.27. Registry RIFT/encoding/PrefixAttributes
The name of the registry should be RIFTEncodingPrefixAttributes. 10.3.27. RIFTEncodingPrefixAttributes Registry
Attributes of a prefix. This registry has the following initial values.
+===================+=======+=========+==========+==================+ +===================+=======+=========+==========+==================+
| Name | Value | Min. | Max. | Comment | | Name | Value | Min. | Max. | Comment |
| | | Schema | Schema | | | | | Schema | Schema | |
| | | Version | Version | | | | | Version | Version | |
+===================+=======+=========+==========+==================+ +===================+=======+=========+==========+==================+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+-------------------+-------+---------+----------+------------------+ +-------------------+-------+---------+----------+------------------+
| metric | 2 | 8.0 | | Distance of the | | metric | 2 | 8.0 | | Distance of the |
| | | | | prefix. | | | | | | prefix. |
+-------------------+-------+---------+----------+------------------+ +-------------------+-------+---------+----------+------------------+
| tags | 3 | 8.0 | | Generic | | tags | 3 | 8.0 | | Generic |
| | | | | unordered set | | | | | | unordered set |
| | | | | of route tags, | | | | | | of route tags, |
| | | | | can be | | | | | | can be |
| | | | | redistributed | | | | | | redistributed |
| | | | | to other | | | | | | to other |
| | | | | protocols or | | | | | | protocols or |
| | | | | use within the | | | | | | used within the |
| | | | | context of real | | | | | | context of real |
| | | | | time analytics. | | | | | | time analytics. |
+-------------------+-------+---------+----------+------------------+ +-------------------+-------+---------+----------+------------------+
| monotonic_clock | 4 | 8.0 | | Monotonic clock | | monotonic_clock | 4 | 8.0 | | Monotonic clock |
| | | | | for mobile | | | | | | for mobile |
| | | | | addresses. | | | | | | addresses. |
+-------------------+-------+---------+----------+------------------+ +-------------------+-------+---------+----------+------------------+
| loopback | 6 | 8.0 | | Indicates if | | loopback | 6 | 8.0 | | Indicates if |
| | | | | the prefix is a | | | | | | the prefix is a |
| | | | | node loopback. | | | | | | node loopback. |
+-------------------+-------+---------+----------+------------------+ +-------------------+-------+---------+----------+------------------+
| directly_attached | 7 | 8.0 | | Indicates that | | directly_attached | 7 | 8.0 | | Indicates that |
| | | | | the prefix is | | | | | | the prefix is |
| | | | | directly | | | | | | directly |
| | | | | attached. | | | | | | attached. |
+-------------------+-------+---------+----------+------------------+ +-------------------+-------+---------+----------+------------------+
| from_link | 10 | 8.0 | | Link to which | | from_link | 10 | 8.0 | | Link to which |
| | | | | the address | | | | | | the address |
| | | | | belongs to. | | | | | | belongs to. |
+-------------------+-------+---------+----------+------------------+ +-------------------+-------+---------+----------+------------------+
| label | 12 | 8.0 | | Optional, per | | label | 12 | 8.0 | | Optional, per- |
| | | | | prefix | | | | | | prefix |
| | | | | significant | | | | | | significant |
| | | | | label. | | | | | | label. |
+-------------------+-------+---------+----------+------------------+ +-------------------+-------+---------+----------+------------------+
Table 34 Table 34: Attributes of a Prefix
10.3.28. Registry RIFT/encoding/PrefixTIEElement
The name of the registry should be RIFTEncodingPrefixTIEElement. 10.3.28. RIFTEncodingPrefixTIEElement Registry
TIE carrying prefixes This registry has the following initial values.
+==========+=======+=============+=============+================+ +==========+=======+=============+=============+================+
| Name | Value | Min. Schema | Max. Schema | Comment | | Name | Value | Min. Schema | Max. Schema | Comment |
| | | Version | Version | | | | | Version | Version | |
+==========+=======+=============+=============+================+ +==========+=======+=============+=============+================+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------+-------+-------------+-------------+----------------+ +----------+-------+-------------+-------------+----------------+
| prefixes | 1 | 8.0 | | Prefixes with | | prefixes | 1 | 8.0 | | Prefixes with |
| | | | | the associated | | | | | | the associated |
| | | | | attributes. | | | | | | attributes. |
+----------+-------+-------------+-------------+----------------+ +----------+-------+-------------+-------------+----------------+
Table 35 Table 35: TIE Carrying Prefixes
10.3.29. Registry RIFT/encoding/ProtocolPacket
The name of the registry should be RIFTEncodingProtocolPacket. 10.3.29. RIFTEncodingProtocolPacket Registry
RIFT packet structure. This registry has the following initial values.
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| header | 1 | 8.0 | | | | header | 1 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| content | 2 | 8.0 | | | | content | 2 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
Table 36 Table 36: RIFT Packet Structure
10.3.30. Registry RIFT/encoding/TIDEPacket
The name of the registry should be RIFTEncodingTIDEPacket. 10.3.30. RIFTEncodingTIDEPacket Registry
TIDE with *sorted* TIE headers. This registry has the following initial values.
+=============+=======+=============+=============+===============+ +=============+=======+=============+=============+===============+
| Name | Value | Min. Schema | Max. Schema | Comment | | Name | Value | Min. Schema | Max. Schema | Comment |
| | | Version | Version | | | | | Version | Version | |
+=============+=======+=============+=============+===============+ +=============+=======+=============+=============+===============+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+-------------+-------+-------------+-------------+---------------+ +-------------+-------+-------------+-------------+---------------+
| start_range | 1 | 8.0 | | First tie | | start_range | 1 | 8.0 | | First TIE |
| | | | | header in the | | | | | | header in the |
| | | | | tide packet. | | | | | | TIDE packet. |
+-------------+-------+-------------+-------------+---------------+ +-------------+-------+-------------+-------------+---------------+
| end_range | 2 | 8.0 | | Last tie | | end_range | 2 | 8.0 | | Last TIE |
| | | | | header in the | | | | | | header in the |
| | | | | tide packet. | | | | | | TIDE packet. |
+-------------+-------+-------------+-------------+---------------+ +-------------+-------+-------------+-------------+---------------+
| headers | 3 | 8.0 | | _sorted_ list | | headers | 3 | 8.0 | | _sorted_ list |
| | | | | of headers. | | | | | | of headers. |
+-------------+-------+-------------+-------------+---------------+ +-------------+-------+-------------+-------------+---------------+
Table 37 Table 37: TIDE with Sorted TIE Headers
10.3.31. Registry RIFT/encoding/TIEElement
The name of the registry should be RIFTEncodingTIEElement.
Single element in a TIE. 10.3.31. RIFTEncodingTIEElement Registry
+=========================================+=====+=======+========+=================================+ This registry has the following initial values.
|Name |Value| Min.| Max.|Comment |
| | | Schema| Schema| |
| | |Version| Version| |
+=========================================+=====+=======+========+=================================+
|Reserved | 0| 8.0| All| |
| | | |Versions| |
+-----------------------------------------+-----+-------+--------+---------------------------------+
|node | 1| 8.0| | Used in case of enum|
| | | | | common.tietypetype.nodetietype.|
+-----------------------------------------+-----+-------+--------+---------------------------------+
|prefixes | 2| 8.0| | Used in case of enum|
| | | | |common.tietypetype.prefixtietype.|
+-----------------------------------------+-----+-------+--------+---------------------------------+
|positive_disaggregation_prefixes | 3| 8.0| | Positive prefixes (always|
| | | | | southbound).|
+-----------------------------------------+-----+-------+--------+---------------------------------+
|negative_disaggregation_prefixes | 5| 8.0| | Transitive, negative prefixes|
| | | | | (always southbound)|
+-----------------------------------------+-----+-------+--------+---------------------------------+
|external_prefixes | 6| 8.0| | Externally reimported prefixes.|
+-----------------------------------------+-----+-------+--------+---------------------------------+
|positive_external_disaggregation_prefixes| 7| 8.0| | Positive external disaggregated|
| | | | | prefixes (always southbound).|
+-----------------------------------------+-----+-------+--------+---------------------------------+
|keyvalues | 9| 8.0| | Key-value store elements.|
+-----------------------------------------+-----+-------+--------+---------------------------------+
Table 38 +========================+=====+=======+========+===================+
|Name |Value|Min. |Max. |Comment |
| | |Schema |Schema | |
| | |Version|Version | |
+========================+=====+=======+========+===================+
|Reserved |0 |8.0 |All | |
| | | |Versions| |
+------------------------+-----+-------+--------+-------------------+
|node |1 |8.0 | |Used in case of |
| | | | |enum |
| | | | |common.tietypetype.|
| | | | |nodetietype. |
+------------------------+-----+-------+--------+-------------------+
|prefixes |2 |8.0 | |Used in case of |
| | | | |enum |
| | | | |common.tietypetype.|
| | | | |prefixtietype. |
+------------------------+-----+-------+--------+-------------------+
|positive_disaggregation_|3 |8.0 | |Positive prefixes |
|prefixes | | | |(always |
| | | | |southbound). |
+------------------------+-----+-------+--------+-------------------+
|negative_disaggregation_|5 |8.0 | |Transitive, |
|prefixes | | | |negative prefixes |
| | | | |(always southbound)|
+------------------------+-----+-------+--------+-------------------+
|external_prefixes |6 |8.0 | |Externally |
| | | | |reimported |
| | | | |prefixes. |
+------------------------+-----+-------+--------+-------------------+
|positive_external_ |7 |8.0 | |Positive external |
|disaggregation_prefixes | | | |disaggregated |
| | | | |prefixes |
| | | | |(always |
| | | | |southbound). |
+------------------------+-----+-------+--------+-------------------+
|keyvalues |9 |8.0 | |Key-value |
| | | | |store elements. |
+------------------------+-----+-------+--------+-------------------+
10.3.32. Registry RIFT/encoding/TIEHeader Table 38: Single Element in a TIE
The name of the registry should be RIFTEncodingTIEHeader. 10.3.32. RIFTEncodingTIEHeader Registry
Header of a TIE. This registry has the following initial values.
+======================+=======+=========+==========+==============+ +======================+=======+=========+==========+==============+
| Name | Value | Min. | Max. | Comment | | Name | Value | Min. | Max. | Comment |
| | | Schema | Schema | | | | | Schema | Schema | |
| | | Version | Version | | | | | Version | Version | |
+======================+=======+=========+==========+==============+ +======================+=======+=========+==========+==============+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------------------+-------+---------+----------+--------------+ +----------------------+-------+---------+----------+--------------+
| tieid | 2 | 8.0 | | Id of tie. | | tieid | 2 | 8.0 | | ID of TIE. |
+----------------------+-------+---------+----------+--------------+ +----------------------+-------+---------+----------+--------------+
| seq_nr | 3 | 8.0 | | Sequence | | seq_nr | 3 | 8.0 | | Sequence |
| | | | | number of | | | | | | number of |
| | | | | tie. | | | | | | TIE. |
+----------------------+-------+---------+----------+--------------+ +----------------------+-------+---------+----------+--------------+
| origination_time | 10 | 8.0 | | Absolute | | origination_time | 10 | 8.0 | | Absolute |
| | | | | timestamp | | | | | | timestamp |
| | | | | when tie was | | | | | | when TIE was |
| | | | | generated. | | | | | | generated. |
+----------------------+-------+---------+----------+--------------+ +----------------------+-------+---------+----------+--------------+
| origination_lifetime | 12 | 8.0 | | Original | | origination_lifetime | 12 | 8.0 | | Original |
| | | | | lifetime | | | | | | lifetime |
| | | | | when tie was | | | | | | when TIE was |
| | | | | generated. | | | | | | generated. |
+----------------------+-------+---------+----------+--------------+ +----------------------+-------+---------+----------+--------------+
Table 39 Table 39: Header of a TIE
10.3.33. Registry RIFT/encoding/TIEHeaderWithLifeTime
The name of the registry should be RIFTEncodingTIEHeaderWithLifeTime. 10.3.33. RIFTEncodingTIEHeaderWithLifeTime Registry
Header of a TIE as described in TIRE/TIDE. This registry has the following initial values.
+====================+=======+=============+==========+===========+ +====================+=======+=============+==========+===========+
| Name | Value | Min. Schema | Max. | Comment | | Name | Value | Min. Schema | Max. | Comment |
| | | Version | Schema | | | | | Version | Schema | |
| | | | Version | | | | | | Version | |
+====================+=======+=============+==========+===========+ +====================+=======+=============+==========+===========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+--------------------+-------+-------------+----------+-----------+ +--------------------+-------+-------------+----------+-----------+
| header | 1 | 8.0 | | | | header | 1 | 8.0 | | |
+--------------------+-------+-------------+----------+-----------+ +--------------------+-------+-------------+----------+-----------+
| remaining_lifetime | 2 | 8.0 | | Remaining | | remaining_lifetime | 2 | 8.0 | | Remaining |
| | | | | lifetime. | | | | | | lifetime. |
+--------------------+-------+-------------+----------+-----------+ +--------------------+-------+-------------+----------+-----------+
Table 40 Table 40: Header of a TIE as Described in TIRE/TIDE
10.3.34. Registry RIFT/encoding/TIEID
The name of the registry should be RIFTEncodingTIEID. 10.3.34. RIFTEncodingTIEID Registry
Unique ID of a TIE. This registry has the following initial values.
+============+=======+=============+=============+============+ +============+=======+=============+=============+============+
| Name | Value | Min. Schema | Max. Schema | Comment | | Name | Value | Min. Schema | Max. Schema | Comment |
| | | Version | Version | | | | | Version | Version | |
+============+=======+=============+=============+============+ +============+=======+=============+=============+============+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+------------+-------+-------------+-------------+------------+ +------------+-------+-------------+-------------+------------+
| direction | 1 | 8.0 | | Direction | | direction | 1 | 8.0 | | Direction |
| | | | | of tie. | | | | | | of TIE. |
+------------+-------+-------------+-------------+------------+ +------------+-------+-------------+-------------+------------+
| originator | 2 | 8.0 | | Indicates | | originator | 2 | 8.0 | | Indicates |
| | | | | originator | | | | | | originator |
| | | | | of tie. | | | | | | of TIE. |
+------------+-------+-------------+-------------+------------+ +------------+-------+-------------+-------------+------------+
| tietype | 3 | 8.0 | | Type of | | tietype | 3 | 8.0 | | Type of |
| | | | | tie. | | | | | | TIE. |
+------------+-------+-------------+-------------+------------+ +------------+-------+-------------+-------------+------------+
| tie_nr | 4 | 8.0 | | Number of | | tie_nr | 4 | 8.0 | | Number of |
| | | | | tie. | | | | | | TIE. |
+------------+-------+-------------+-------------+------------+ +------------+-------+-------------+-------------+------------+
Table 41 Table 41: Unique ID of a TIE
10.3.35. Registry RIFT/encoding/TIEPacket
The name of the registry should be RIFTEncodingTIEPacket. 10.3.35. RIFTEncodingTIEPacket Registry
TIE packet This registry has the following initial values.
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| header | 1 | 8.0 | | | | header | 1 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| element | 2 | 8.0 | | | | element | 2 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
Table 42 Table 42: TIE Packet
10.3.36. Registry RIFT/encoding/TIREPacket
The name of the registry should be RIFTEncodingTIREPacket. 10.3.36. RIFTEncodingTIREPacket Registry
TIRE packet This registry has the following initial values.
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Name | Value | Min. Schema Version | Max. Schema | Comment | | Name | Value | Min. Schema Version | Max. Schema | Comment |
| | | | Version | | | | | | Version | |
+==========+=======+=====================+=============+=========+ +==========+=======+=====================+=============+=========+
| Reserved | 0 | 8.0 | All | | | Reserved | 0 | 8.0 | All | |
| | | | Versions | | | | | | Versions | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
| headers | 1 | 8.0 | | | | headers | 1 | 8.0 | | |
+----------+-------+---------------------+-------------+---------+ +----------+-------+---------------------+-------------+---------+
Table 43 Table 43: TIRE Packet
11. Acknowledgments
A new routing protocol in its complexity is not a product of a parent
but of a village as the author list shows already. However, many
more people provided input, fine-combed the specification based on
their experience in design, implementation or application of
protocols in IP fabrics. This section will make an inadequate
attempt in recording their contribution.
Many thanks to Naiming Shen for some of the early discussions around
the topic of using IGPs for routing in topologies related to Clos.
Russ White to be especially acknowledged for the key conversation on
epistemology that allowed to tie current asynchronous distributed
systems theory results to a modern protocol design presented in this
scope. Adrian Farrel, Joel Halpern, Jeffrey Zhang, Krzysztof
Szarkowicz, Nagendra Kumar, Melchior Aelmans, Kaushal Tank, Will
Jones, Moin Ahmed, Sandy Zhang, Donald Eastlake provided thoughtful
comments that improved the readability of the document and found good
amount of corners where the light failed to shine. Kris Price was
first to mention single router, single arm default considerations.
Jeff Tantsura helped out with some initial thoughts on BFD
interactions while Jeff Haas corrected several misconceptions about
BFD's finer points and helped to improve the security section around
leaf considerations. Artur Makutunowicz pointed out many possible
improvements and acted as sounding board in regard to modern protocol
implementation techniques RIFT is exploring. Barak Gafni formalized
first time clearly the problem of partitioned spine and fallen leaves
on a (clean) napkin in Singapore that led to the very important part
of the specification centered around multiple ToF planes and negative
disaggregation. Igor Gashinsky and others shared many thoughts on
problems encountered in design and operation of large-scale data
center fabrics. Xu Benchong found a delicate error in the flooding
procedures and a schema datatype size mismatch.
Too many people to mention provided reviews from many directions in
IETF, often pointing to critical defects, sometimes asking for things
again that have been removed by one the previous reviewers as
objectionable or superfluous, and many times claiming the document
being somewhere on the extremes between too crowded with the obvious
and omitting introduction to cryptic concepts everywhere. The result
is the best editors could do to find a balance of a document guiding
the reader by Section 2 into a specification tight enough to result
in interoperable implementations while at the same time introducing
enough operational context of IP routable fabrics to guarantee a
concise, common language when facing unaccustomed concepts the
protocol relies on. In the process it was important to not end up
carrying Aesop's donkey of course so while the result may not be
perceived as perfect by everyone it should be practically speaking
more than sufficient for everyone that ends up using it in the
future.
Last but not least, Alvaro Retana, John Scudder, Andrew Alston and
Jim Guichard guided the undertaking as ADs by asking many necessary
procedural and technical questions which did not only improve the
content but did also lay out the track towards publication. And
Roman Danyliw is mentioned very last but not least either for his
painstakingly detailed review and improvement of security aspects of
the specification.
12. Contributors
This work is a product of a list of individuals which are all to be
considered major contributors independent of the fact whether their
name made it to the limited boilerplate author's list or not.
+======================+===+==================+===+================+
+======================+===+==================+===+================+
| Tony Przygienda, Ed. | | | | | | Pascal Thubert |
+----------------------+---+------------------+---+----------------+
| Juniper | | | | | | Cisco |
+----------------------+---+------------------+---+----------------+
| Bruno Rijsman | | | Jordan Head, Ed. | | | Dmitry |
| | | | | Afanasiev |
+----------------------+---+------------------+---+----------------+
| Individual | | | Juniper | | | Individual |
+----------------------+---+------------------+---+----------------+
| Don Fedyk | | | Alia Atlas | | | John Drake |
+----------------------+---+------------------+---+----------------+
| LabN | | | Individual | | | Individual |
+----------------------+---+------------------+---+----------------+
| Ilya Vershkov | | | | | | | | |
+----------------------+---+------------------+---+----------------+
| NVidia | | | | | | | | |
+----------------------+---+------------------+---+----------------+
Table 44: RIFT Authors
13. References 11. References
13.1. Normative References 11.1. Normative References
[EUI64] IEEE, "Guidelines for Use of Extended Unique Identifier [EUI64] IEEE, "Guidelines for Use of Extended Unique Identifier
(EUI), Organizationally Unique Identifier (OUI), and (EUI), Organizationally Unique Identifier (OUI), and
Company ID (CID)", IEEE EUI, Company ID (CID)", <https://standards-support.ieee.org/hc/
<http://standards.ieee.org/develop/regauth/tut/eui.pdf>. en-us/articles/4888705676564-Guidelines-for-Use-of-
Extended-Unique-Identifier-EUI-Organizationally-Unique-
Identifier-OUI-and-Company-ID-CID>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2365] Meyer, D., "Administratively Scoped IP Multicast", BCP 23, [RFC2365] Meyer, D., "Administratively Scoped IP Multicast", BCP 23,
RFC 2365, DOI 10.17487/RFC2365, July 1998, RFC 2365, DOI 10.17487/RFC2365, July 1998,
<https://www.rfc-editor.org/info/rfc2365>. <https://www.rfc-editor.org/info/rfc2365>.
skipping to change at page 180, line 21 skipping to change at line 7856
[RFC9300] Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A. [RFC9300] Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A.
Cabellos, Ed., "The Locator/ID Separation Protocol Cabellos, Ed., "The Locator/ID Separation Protocol
(LISP)", RFC 9300, DOI 10.17487/RFC9300, October 2022, (LISP)", RFC 9300, DOI 10.17487/RFC9300, October 2022,
<https://www.rfc-editor.org/info/rfc9300>. <https://www.rfc-editor.org/info/rfc9300>.
[RFC9301] Farinacci, D., Maino, F., Fuller, V., and A. Cabellos, [RFC9301] Farinacci, D., Maino, F., Fuller, V., and A. Cabellos,
Ed., "Locator/ID Separation Protocol (LISP) Control Ed., "Locator/ID Separation Protocol (LISP) Control
Plane", RFC 9301, DOI 10.17487/RFC9301, October 2022, Plane", RFC 9301, DOI 10.17487/RFC9301, October 2022,
<https://www.rfc-editor.org/info/rfc9301>. <https://www.rfc-editor.org/info/rfc9301>.
[SHA-2] National Institute of Standards and Technology, "Secure [SHA-2] NIST, "Secure Hash Standard (SHS)", FIPS PUB 180-4,
Hash Standard, FIPS PUB 180-3", 2008. DOI 10.6028/NIST.FIPS.180-4, July 2015,
<https://csrc.nist.gov/pubs/fips/180-4/upd1/final>.
[thrift] Apache Software Foundation, "Thrift Language [thrift] Apache Software Foundation, "Apache Thrift Documentation",
Implementation and Documentation", <https://thrift.apache.org/docs/>.
<https://github.com/apache/thrift/tree/0.15.0/doc>.
13.2. Informative References 11.2. Informative References
[APPLICABILITY] [APPLICABILITY]
Wei, Y., Zhang, Z., Afanasiev, D., Thubert, P., and T. Wei, Y., Zhang, Z., Afanasiev, D., Thubert, P., and T.
Przygienda, "RIFT Applicability", Work in Progress, Przygienda, "RIFT Applicability and Operational
Internet-Draft, draft-ietf-rift-applicability-15, 13 May Considerations", Work in Progress, Internet-Draft, draft-
2024, <https://datatracker.ietf.org/doc/html/draft-ietf- ietf-rift-applicability-17, 17 June 2024,
rift-applicability-15>. <https://datatracker.ietf.org/doc/html/draft-ietf-rift-
applicability-17>.
[CLOS] Yuan, X., "On Nonblocking Folded-Clos Networks in Computer [CLOS] Yuan, X., "On Nonblocking Folded-Clos Networks in Computer
Communication Environments", IEEE International Parallel & Communication Environments", 2011 IEEE International
Distributed Processing Symposium, 2011. Parallel & Distributed Processing Symposium,
DOI 10.1109/IPDPS.2011.27, 2011,
<https://ieeexplore.ieee.org/document/6012836>.
[DayOne] Aelmans, M., Vandezande, O., Rijsman, B., Head, J., Graf, [DayOne] Aelmans, M., Vandezande, O., Rijsman, B., Head, J., Graf,
C., Alberro, L., Mali, H., and O. Steudler, "Day One: C., Alberro, L., Mali, H., and O. Steudler, "Day One:
Routing in Fat Trees (RIFT)", Juniper DayOne . Routing in Fat Trees (RIFT)", Juniper Network Books,
ISBN 978-1-7363160-0-9, December 2020.
[DIJKSTRA] Dijkstra, E. W., "A Note on Two Problems in Connexion with [DIJKSTRA] Dijkstra, E. W., "A Note on Two Problems in Connexion with
Graphs", Journal Numer. Math. , 1959. Graphs", Numerische Mathematik, vol. 1, pp. 269-271,
DOI 10.1007/BF01386390, December 1959,
<https://link.springer.com/article/10.1007/BF01386390>.
[DYNAMO] De Candia et al., G., "Dynamo: amazon's highly available [DYNAMO] De Candia, G., Hastorun, D., Jampani, M., Kakulpati, G.,
key-value store", ACM SIGOPS symposium on Operating Lakshman, A., Pilchin, A., Sivasubramanian, S., Vosshall,
systems principles (SOSP '07), 2007. P., and W. Vogels, "Dynamo: amazon's highly available key-
value store", ACM SIGOPS Operating Systems Review, vol.
41, no. 6, pp. 205-220, DOI 10.1145/1323293.1294281, 2007,
<https://dl.acm.org/doi/10.1145/1323293.1294281>.
[EPPSTEIN] Eppstein, D., "Finding the k-Shortest Paths", 1997. [EPPSTEIN] Eppstein, D., "Finding the k Shortest Paths", 1997,
<https://ics.uci.edu/~eppstein/pubs/Epp-SJC-98.pdf>.
[FATTREE] Leiserson, C. E., "Fat-Trees: Universal Networks for [FATTREE] Leiserson, C. E., "Fat-Trees: Universal Networks for
Hardware-Efficient Supercomputing", 1985. Hardware-Efficient Supercomputing", IEEE Transactions on
Computers, vol. C-34, no. 10, pp. 892-901,
DOI 10.1109/TC.1985.6312192, October 1985,
<https://ieeexplore.ieee.org/document/6312192>.
[IEEEstd1588] [IEEEstd1588]
IEEE, "IEEE Standard for a Precision Clock Synchronization IEEE, "IEEE Standard for a Precision Clock Synchronization
Protocol for Networked Measurement and Control Systems", Protocol for Networked Measurement and Control Systems",
IEEE Standard 1588, IEEE Std 1588-2008, DOI 10.1109/IEEESTD.2008.4579760, July
<https://ieeexplore.ieee.org/document/4579760/>. 2008, <https://ieeexplore.ieee.org/document/4579760/>.
[IEEEstd8021AS] [IEEEstd8021AS]
IEEE, "IEEE Standard for Local and Metropolitan Area IEEE, "IEEE Standard for Local and Metropolitan Area
Networks - Timing and Synchronization for Time-Sensitive Networks - Timing and Synchronization for Time-Sensitive
Applications in Bridged Local Area Networks", Applications in Bridged Local Area Networks", IEEE Std
IEEE Standard 802.1AS, 802.1AS-2011, DOI 10.1109/IEEESTD.2011.5741898, March
<https://ieeexplore.ieee.org/document/5741898/>. 2011, <https://ieeexplore.ieee.org/document/5741898/>.
[RFC0826] Plummer, D., "An Ethernet Address Resolution Protocol: Or [RFC0826] Plummer, D., "An Ethernet Address Resolution Protocol: Or
Converting Network Protocol Addresses to 48.bit Ethernet Converting Network Protocol Addresses to 48.bit Ethernet
Address for Transmission on Ethernet Hardware", STD 37, Address for Transmission on Ethernet Hardware", STD 37,
RFC 826, DOI 10.17487/RFC0826, November 1982, RFC 826, DOI 10.17487/RFC0826, November 1982,
<https://www.rfc-editor.org/info/rfc826>. <https://www.rfc-editor.org/info/rfc826>.
[RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982,
DOI 10.17487/RFC1982, August 1996, DOI 10.17487/RFC1982, August 1996,
<https://www.rfc-editor.org/info/rfc1982>. <https://www.rfc-editor.org/info/rfc1982>.
skipping to change at page 182, line 20 skipping to change at line 7963
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007, DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>. <https://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007, DOI 10.17487/RFC4862, September 2007,
<https://www.rfc-editor.org/info/rfc4862>. <https://www.rfc-editor.org/info/rfc4862>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
[RFC5837] Atlas, A., Ed., Bonica, R., Ed., Pignataro, C., Ed., Shen, [RFC5837] Atlas, A., Ed., Bonica, R., Ed., Pignataro, C., Ed., Shen,
N., and JR. Rivers, "Extending ICMP for Interface and N., and JR. Rivers, "Extending ICMP for Interface and
Next-Hop Identification", RFC 5837, DOI 10.17487/RFC5837, Next-Hop Identification", RFC 5837, DOI 10.17487/RFC5837,
April 2010, <https://www.rfc-editor.org/info/rfc5837>. April 2010, <https://www.rfc-editor.org/info/rfc5837>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>. <https://www.rfc-editor.org/info/rfc5880>.
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550, Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012, DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>. <https://www.rfc-editor.org/info/rfc6550>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters, Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018, RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>. <https://www.rfc-editor.org/info/rfc8415>.
[VAHDAT08] Al-Fares, M., Loukissas, A., and A. Vahdat, "A Scalable, [VAHDAT08] Al-Fares, M., Loukissas, A., and A. Vahdat, "A Scalable,
Commodity Data Center Network Architecture", SIGCOMM , Commodity Data Center Network Architecture", ACM SIGCOMM
2008. Computer Communication Review, vol. 38, no. 4, pp. 63-74,
DOI 10.1145/1402946.1402967, August 2008,
<https://dl.acm.org/doi/10.1145/1402946.1402967>.
[VFR] Giotsas, V. and S. Zhou, "Valley-free violation in [VFR] Giotsas, V. and S. Zhou, "Valley-free violation in
Internet routing - Analysis based on BGP Community data", Internet routing - Analysis based on BGP Community data",
2012 IEEE International Conference on Communications 2012 IEEE International Conference on Communications
(ICC) , 2012. (ICC), DOI 10.1109/ICC.2012.6363987, 2012,
<https://ieeexplore.ieee.org/document/6363987>.
Appendix A. Sequence Number Binary Arithmetic Appendix A. Sequence Number Binary Arithmetic
This section defines a variant of sequence number arithmetic related This section defines a variant of sequence number arithmetic related
to [RFC1982] explained over two complement arithmetic which is easy to [RFC1982] explained over two complement arithmetic, which is easy
to implement. to implement.
Assuming straight two complement's subtractions on the bit-width of Assuming straight two complement's subtractions on the bit width of
the sequence numbers, the corresponding >: and =: relations are the sequence numbers, the corresponding >: and =: relations are
defined as: defined as:
U_1, U_2 are 12-bits aligned unsigned version number * U_1, U_2 are 12-bits aligned unsigned version number
D_f is ( U_1 - U_2 ) interpreted as two complement signed 12-bits * D_f is ( U_1 - U_2 ) interpreted as two complement signed 12-bits
D_b is ( U_2 - U_1 ) interpreted as two complement signed 12-bits
U_1 >: U_2 IIF D_f > 0 *and* D_b < 0 * D_b is ( U_2 - U_1 ) interpreted as two complement signed 12-bits
U_1 =: U_2 IIF D_f = 0
* U_1 >: U_2 IIF D_f > 0 *and* D_b < 0
* U_1 =: U_2 IIF D_f = 0
The >: relationship is anti-symmetric but not transitive. Observe The >: relationship is anti-symmetric but not transitive. Observe
that this leaves >: of the numbers having maximum two complement that this leaves >: of the numbers having maximum two complement
distance, e.g. ( 0 and 0x800 ) undefined in the 12-bits case since distance, e.g., ( 0 and 0x800 ) undefined in the 12-bits case since
D_f and D_b are both -0x7ff. D_f and D_b are both -0x7ff.
A simple example of the relationship in case of 3-bit arithmetic A simple example of the relationship in case of 3-bit arithmetic
follows as table indicating D_f/D_b values and then the relationship follows as table indicating D_f/D_b values and then the relationship
of U_1 to U_2: of U_1 to U_2:
U2 / U1 0 1 2 3 4 5 6 7 +=========+=====+=====+=====+=====+=====+=====+=====+=====+
0 +/+ +/- +/- +/- -/- -/+ -/+ -/+ | U2 / U1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
1 -/+ +/+ +/- +/- +/- -/- -/+ -/+ +=========+=====+=====+=====+=====+=====+=====+=====+=====+
2 -/+ -/+ +/+ +/- +/- +/- -/- -/+ | 0 | +/+ | +/- | +/- | +/- | -/- | -/+ | -/+ | -/+ |
3 -/+ -/+ -/+ +/+ +/- +/- +/- -/- +---------+-----+-----+-----+-----+-----+-----+-----+-----+
4 -/- -/+ -/+ -/+ +/+ +/- +/- +/- | 1 | -/+ | +/+ | +/- | +/- | +/- | -/- | -/+ | -/+ |
5 +/- -/- -/+ -/+ -/+ +/+ +/- +/- +---------+-----+-----+-----+-----+-----+-----+-----+-----+
6 +/- +/- -/- -/+ -/+ -/+ +/+ +/- | 2 | -/+ | -/+ | +/+ | +/- | +/- | +/- | -/- | -/+ |
7 +/- +/- +/- -/- -/+ -/+ -/+ +/+ +---------+-----+-----+-----+-----+-----+-----+-----+-----+
U2 / U1 0 1 2 3 4 5 6 7 | 3 | -/+ | -/+ | -/+ | +/+ | +/- | +/- | +/- | -/- |
0 = > > > ? < < < +---------+-----+-----+-----+-----+-----+-----+-----+-----+
1 < = > > > ? < < | 4 | -/- | -/+ | -/+ | -/+ | +/+ | +/- | +/- | +/- |
2 < < = > > > ? < +---------+-----+-----+-----+-----+-----+-----+-----+-----+
3 < < < = > > > ? | 5 | +/- | -/- | -/+ | -/+ | -/+ | +/+ | +/- | +/- |
4 ? < < < = > > > +---------+-----+-----+-----+-----+-----+-----+-----+-----+
5 > ? < < < = > > | 6 | +/- | +/- | -/- | -/+ | -/+ | -/+ | +/+ | +/- |
6 > > ? < < < = > +---------+-----+-----+-----+-----+-----+-----+-----+-----+
7 > > > ? < < < = | 7 | +/- | +/- | +/- | -/- | -/+ | -/+ | -/+ | +/+ |
+---------+-----+-----+-----+-----+-----+-----+-----+-----+
Table 44
+=========+===+===+===+===+===+===+===+===+
| U2 / U1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
+=========+===+===+===+===+===+===+===+===+
| 0 | = | > | > | > | ? | < | < | < |
+---------+---+---+---+---+---+---+---+---+
| 1 | < | = | > | > | > | ? | < | < |
+---------+---+---+---+---+---+---+---+---+
| 2 | < | < | = | > | > | > | ? | < |
+---------+---+---+---+---+---+---+---+---+
| 3 | < | < | < | = | > | > | > | ? |
+---------+---+---+---+---+---+---+---+---+
| 4 | ? | < | < | < | = | > | > | > |
+---------+---+---+---+---+---+---+---+---+
| 5 | > | ? | < | < | < | = | > | > |
+---------+---+---+---+---+---+---+---+---+
| 6 | > | > | ? | < | < | < | = | > |
+---------+---+---+---+---+---+---+---+---+
| 7 | > | > | > | ? | < | < | < | = |
+---------+---+---+---+---+---+---+---+---+
Table 45
Appendix B. Examples Appendix B. Examples
B.1. Normal Operation B.1. Normal Operation
^ N +--------+ +--------+ ^ N +--------+ +--------+
Level 2 | |ToF 21| |ToF 22| Level 2 | |ToF 21| |ToF 22|
E <-*-> W ++-+--+-++ ++-+--+-++ E <-*-> W ++-+--+-++ ++-+--+-++
| | | | | | | | | | | | | | | | | |
S v P111/2 |P121/2 | | | | S v P111/2 |P121/2 | | | |
skipping to change at page 184, line 48 skipping to change at line 8109
| +---0/0--->-----+ 0/0 | +----------------+ | | +---0/0--->-----+ 0/0 | +----------------+ |
0/0 | | | | | | | 0/0 | | | | | | |
| +---<-0/0-----+ | v | +--------------+ | | | +---<-0/0-----+ | v | +--------------+ | |
v | | | | | | | v | | | | | | |
+-+---+-+ +--+--+-+ +-+---+-+ +---+-+-+ +-+---+-+ +--+--+-+ +-+---+-+ +---+-+-+
Level 0 | | | | | | | | Level 0 | | | | | | | |
|Leaf111| |Leaf112| |Leaf121| |Leaf122| |Leaf111| |Leaf112| |Leaf121| |Leaf122|
+-+-----+ +-+---+-+ +--+--+-+ +-+-----+ +-+-----+ +-+---+-+ +--+--+-+ +-+-----+
+ + \ / + + + + \ / + +
Prefix111 Prefix112 \ / Prefix121 Prefix122 Prefix111 Prefix112 \ / Prefix121 Prefix122
multi-homed multihomed
Prefix Prefix
+---------- PoD 1 ---------+ +---------- PoD 2 ---------+ +---------- PoD 1 ---------+ +---------- PoD 2 ---------+
Figure 35: Normal Case Topology Figure 35: Normal Case Topology
This section describes RIFT deployment in the example topology given This section describes RIFT deployment in the example topology given
in Figure 35 without any node or link failures. The scenario in Figure 35 without any node or link failures. The scenario
disregards flooding reduction for simplicity's sake and compresses disregards flooding reduction for simplicity's sake and compresses
the node names in some cases to fit them into the picture better. the node names in some cases to fit them into the picture better.
First, the following bi-directional adjacencies will be established: First, the following bidirectional adjacencies will be established:
1. ToF 21 (PoD 0) to Spine 111, Spine 112, Spine 121, and Spine 122 1. ToF 21 (PoD 0) to Spine 111, Spine 112, Spine 121, and Spine 122
2. ToF 22 (PoD 0) to Spine 111, Spine 112, Spine 121, and Spine 122 2. ToF 22 (PoD 0) to Spine 111, Spine 112, Spine 121, and Spine 122
3. Spine 111 to Leaf 111, Leaf 112 3. Spine 111 to Leaf 111 and Leaf 112
4. Spine 112 to Leaf 111, Leaf 112 4. Spine 112 to Leaf 111 and Leaf 112
5. Spine 121 to Leaf 121, Leaf 122 5. Spine 121 to Leaf 121 and Leaf 122
6. Spine 122 to Leaf 121, Leaf 122 6. Spine 122 to Leaf 121 and Leaf 122
Leaf 111 and Leaf 112 originate N-TIEs for Prefix 111 and Prefix 112 Leaf 111 and Leaf 112 originate N-TIEs for Prefix 111 and Prefix 112
(respectively) to both Spine 111 and Spine 112 (Leaf 112 also (respectively) to both Spine 111 and Spine 112 (Leaf 112 also
originates an N-TIE for the multi-homed prefix). Spine 111 and Spine originates an N-TIE for the multihomed prefix). Spine 111 and Spine
112 will then originate their own N-TIEs, as well as flood the N-TIEs 112 will then originate their own N-TIEs, as well as flood the N-TIEs
received from Leaf 111 and Leaf 112 to both ToF 21 and ToF 22. received from Leaf 111 and Leaf 112 to both ToF 21 and ToF 22.
Similarly, Leaf 121 and Leaf 122 originate North TIEs for Prefix 121 Similarly, Leaf 121 and Leaf 122 originate North TIEs for Prefix 121
and Prefix 122 (respectively) to Spine 121 and Spine 122 (Leaf 121 and Prefix 122 (respectively) to Spine 121 and Spine 122 (Leaf 121
also originates a North TIE for the multi-homed prefix). Spine 121 also originates a North TIE for the multihomed prefix). Spine 121
and Spine 122 will then originate their own North TIEs, as well as and Spine 122 will then originate their own North TIEs, as well as
flood the North TIEs received from Leaf 121 and Leaf 122 to both ToF flood the North TIEs received from Leaf 121 and Leaf 122 to both ToF
21 and ToF 22. 21 and ToF 22.
Spines hold only North TIEs of level 0 for their PoD, while leaves Spines hold only North TIEs of level 0 for their PoD, while leaves
only hold their own North TIEs while, at this point, both ToF 21 and only hold their own North TIEs while, at this point, both ToF 21 and
ToF 22 (as well as any northbound connected controllers) would have ToF 22 (as well as any northbound connected controllers) would have
the complete network topology. the complete network topology.
ToF 21 and ToF 22 would then originate and flood South TIEs ToF 21 and ToF 22 would then originate and flood South TIEs
containing any established adjacencies and a default IP route to all containing any established adjacencies and a default IP route to all
spines. Spine 111, Spine 112, Spine 121, and Spine 122 will reflect spines. Spine 111, Spine 112, Spine 121, and Spine 122 will reflect
all Node South TIEs received from ToF 21 to ToF 22, and all Node all Node South TIEs received from ToF 21 to ToF 22 and all Node South
South TIEs from ToF 22 to ToF 21. South TIEs will not be re- TIEs from ToF 22 to ToF 21. South TIEs will not be re-propagated
propagated southbound. southbound.
South TIEs containing a default IP route are then originated by both South TIEs containing a default IP route are then originated by both
Spine 111 and Spine 112 toward Leaf 111 and Leaf 112. Similarly, Spine 111 and Spine 112 towards Leaf 111 and Leaf 112. Similarly,
South TIEs containing a default IP route are originated by Spine 121 South TIEs containing a default IP route are originated by Spine 121
and Spine 122 toward Leaf 121 and Leaf 122. and Spine 122 towards Leaf 121 and Leaf 122.
At this point IP connectivity across maximum number of viable paths At this point, IP connectivity across the maximum number of viable
has been established for all leaves, with routing information paths has been established for all leaves, with routing information
constrained to only the minimum amount that allows for normal constrained to only the minimum amount that allows for normal
operation and redundancy. operation and redundancy.
B.2. Leaf Link Failure B.2. Leaf Link Failure
| | | | | | | |
+-+---+-+ +-+---+-+ +-+---+-+ +-+---+-+
| | | | | | | |
|Spin111| |Spin112| |Spin111| |Spin112|
+-+---+-+ ++----+-+ +-+---+-+ ++----+-+
skipping to change at page 187, line 11 skipping to change at line 8205
will be reflected to Spine 111. Necessary SPF recomputation will will be reflected to Spine 111. Necessary SPF recomputation will
occur, resulting in Spine 112 no longer being in the forwarding path occur, resulting in Spine 112 no longer being in the forwarding path
for Prefix 112. for Prefix 112.
Spine 111 will also disaggregate Prefix 112 by sending new Prefix Spine 111 will also disaggregate Prefix 112 by sending new Prefix
South TIE to Leaf 111 and Leaf 112. Though disaggregation is covered South TIE to Leaf 111 and Leaf 112. Though disaggregation is covered
in more detail in the following section, it is worth mentioning in in more detail in the following section, it is worth mentioning in
this example as it further illustrates RIFT's mechanism to mitigate this example as it further illustrates RIFT's mechanism to mitigate
traffic loss. Consider that Leaf 111 has yet to receive the more traffic loss. Consider that Leaf 111 has yet to receive the more
specific (disaggregated) route from Spine 111. In such a scenario, specific (disaggregated) route from Spine 111. In such a scenario,
traffic from Leaf 111 toward Prefix 112 may still use Spine 112's traffic from Leaf 111 towards Prefix 112 may still use Spine 112's
default route, causing it to traverse ToF 21 and ToF 22 back down via default route, causing it to traverse ToF 21 and ToF 22 back down via
Spine 111. While this behavior is suboptimal, it is transient in Spine 111. While this behavior is suboptimal, it is transient in
nature and preferred to dropping traffic. nature and preferred to dropping traffic.
B.3. Partitioned Fabric B.3. Partitioned Fabric
+--------+ +--------+ +--------+ +--------+
Level 2 |ToF 21| |ToF 22| Level 2 |ToF 21| |ToF 22|
++-+--+-++ ++-+--+-++ ++-+--+-++ ++-+--+-++
| | | | | | | | | | | | | | | |
skipping to change at page 188, line 5 skipping to change at line 8246
+-+---+-+ +--+--+-+ +-+---+-+ +---+-+-+ +-+---+-+ +--+--+-+ +-+---+-+ +---+-+-+
Level 3 | | | | | | | | Level 3 | | | | | | | |
|Leaf111| |Leaf112| |Leaf121| |Leaf122| |Leaf111| |Leaf112| |Leaf121| |Leaf122|
+-+-----+ ++------+ +-----+-+ +-+-----+ +-+-----+ ++------+ +-----+-+ +-+-----+
+ + + + + + + +
Prefix111 Prefix112 Prefix121 Prefix122 Prefix111 Prefix112 Prefix121 Prefix122
1.1/16 1.1/16
Figure 37: Fabric Partition Figure 37: Fabric Partition
Figure 37 shows one of more catastrophic scenarios where ToF 21 is Figure 37 shows more catastrophic scenario where ToF 21 is completely
completely severed from access to Prefix 121 due to a double link severed from access to Prefix 121 due to a double link failure. If
failure. If only default routes existed, this would result in 50% of only default routes existed, this would result in 50% of traffic from
traffic from Leaf 111 and Leaf 112 toward Prefix 121 being dropped. Leaf 111 and Leaf 112 towards Prefix 121 being dropped.
The mechanism to resolve this scenario hinges on ToF 21's South TIEs The mechanism to resolve this scenario hinges on ToF 21's South TIEs
being reflected from Spine 111 and Spine 112 to ToF 22. Once ToF 22 being reflected from Spine 111 and Spine 112 to ToF 22. Once ToF 22
is informed that Prefix 121 cannot be reached from ToF 21, it will is informed that Prefix 121 cannot be reached from ToF 21, it will
begin to disaggregate Prefix 121 by advertising a more specific route begin to disaggregate Prefix 121 by advertising a more specific route
(1.1/16) along with the default IP prefix route to all spines (ToF 21 (1.1/16), along with the default IP prefix route to all spines (ToF
still only sends a default route). The result is Spine 111 and 21 still only sends a default route). The result is Spine 111 and
Spine112 using the more specific route to Prefix 121 via ToF 22. All Spine 112 using the more specific route to Prefix 121 via ToF 22.
other prefixes continue to use the default IP prefix route toward All other prefixes continue to use the default IP prefix route
both ToF 21 and ToF 22. towards both ToF 21 and ToF 22.
The more specific route for Prefix 121 being advertised by ToF 22 The more specific route for Prefix 121 being advertised by ToF 22
does not need to be propagated further south to the leaves, as they does not need to be propagated further south to the leaves, as they
do not benefit from this information. Spine 111 and Spine 112 are do not benefit from this information. Spine 111 and Spine 112 are
only required to reflect the new South Node TIEs received from ToF 22 only required to reflect the new South Node TIEs received from ToF 22
to ToF 21. In short, only the relevant nodes received the relevant to ToF 21. In short, only the relevant nodes received the relevant
updates, thereby restricting the failure to only the partitioned updates, thereby restricting the failure to only the partitioned
level rather than burdening the whole fabric with the flooding and level rather than burdening the whole fabric with the flooding and
recomputation of the new topology information. recomputation of the new topology information.
To finish this example, the following table shows sets computed by To finish this example, the following list shows sets computed by ToF
ToF 22 using notation introduced in Section 6.5: 22 using notation introduced in Section 6.5:
|R = Prefix 111, Prefix 112, Prefix 121, Prefix 122 * R = Prefix 111, Prefix 112, Prefix 121, Prefix 122
|H (for r=Prefix 111) = Spine 111, Spine 112 * H (for r=Prefix 111) = Spine 111, Spine 112
|H (for r=Prefix 112) = Spine 111, Spine 112 * H (for r=Prefix 112) = Spine 111, Spine 112
|H (for r=Prefix 121) = Spine 121, Spine 122 * H (for r=Prefix 121) = Spine 121, Spine 122
|H (for r=Prefix 122) = Spine 121, Spine 122 * H (for r=Prefix 122) = Spine 121, Spine 122
|A (for ToF 21) = Spine 111, Spine 112 * A (for ToF 21) = Spine 111, Spine 112
With that and |H (for r=Prefix 121) and |H (for r=Prefix 122) being With that and |H (for r=Prefix 121) and |H (for r=Prefix 122) being
disjoint from |A (for ToF 21), ToF 22 will originate a South TIE with disjoint from |A (for ToF 21), ToF 22 will originate a South TIE with
Prefix 121 and Prefix 122, which will be flooded to all spines. Prefix 121 and Prefix 122, which will be flooded to all spines.
B.4. Northbound Partitioned Router and Optional East-West Links B.4. Northbound Partitioned Router and Optional East-West Links
+ + + + + +
X N1 | N2 | N3 X N1 | N2 | N3
X | | X | |
+--+----+ +--+----+ +--+-----+ +--+----+ +--+----+ +--+-----+
| |0/0> <0/0| |0/0> <0/0| | | |0/0> <0/0| |0/0> <0/0| |
| A01 +----------+ A02 +----------+ A03 | Level 1 | A01 +----------+ A02 +----------+ A03 | Level 1
++-+-+--+ ++--+--++ +---+-+-++ ++-+-+--+ ++--+--++ +---+-+-++
| | | | | | | | | | | | | | | | | |
| | +----------------------------------+ | | | | | +----------------------------------+ | | |
| | | | | | | | | | | | | | | | | |
skipping to change at page 189, line 29 skipping to change at line 8316
| | | | | | | | | | | | | | | | | |
++-+-+--+ | +---+---+ | +-+---+-++ ++-+-+--+ | +---+---+ | +-+---+-++
| | +-+ +-+ | | | | +-+ +-+ | |
| L01 | | L02 | | L03 | Level 0 | L01 | | L02 | | L03 | Level 0
+-------+ +-------+ +--------+ +-------+ +-------+ +--------+
Figure 38: North Partitioned Router Figure 38: North Partitioned Router
Figure 38 shows a part of a fabric where level 1 is horizontally Figure 38 shows a part of a fabric where level 1 is horizontally
connected and A01 lost its only northbound adjacency. Based on N-SPF connected and A01 lost its only northbound adjacency. Based on N-SPF
rules in Section 6.4.1 A01 will compute northbound reachability by rules in Section 6.4.1, A01 will compute northbound reachability by
using the link A01 to A02. A02 however, will *not* use this link using the link A01 to A02. However, A02 will *not* use this link
during N-SPF. The result is A01 utilizing the horizontal link for during N-SPF. The result is A01 utilizing the horizontal link for
default route advertisement and unidirectional routing. default route advertisement and unidirectional routing.
Furthermore, if A02 also loses its only northbound adjacency (N2), Furthermore, if A02 also loses its only northbound adjacency (N2),
the situation evolves. A01 will no longer have northbound the situation evolves. A01 will no longer have northbound
reachability while it receives A03's northbound adjacencies in South reachability while it receives A03's northbound adjacencies in South
Node TIEs reflected by nodes south of it. As a result, A01 will no Node TIEs reflected by nodes south of it. As a result, A01 will no
longer advertise its default route in accordance with Section 6.3.8. longer advertise its default route in accordance with Section 6.3.8.
Acknowledgments
A new routing protocol in its complexity is not a product of a parent
but of a village, as the author list already shows. However, many
more people provided input and fine-combed the specification based on
their experience in design, implementation, or application of
protocols in IP fabrics. This section will make an inadequate
attempt in recording their contribution.
Many thanks to Naiming Shen for some of the early discussions around
the topic of using IGPs for routing in topologies related to Clos.
Russ White is especially acknowledged for the key conversation on
epistemology that tied the current asynchronous distributed systems
theory results to a modern protocol design presented in this scope.
Adrian Farrel, Joel Halpern, Jeffrey Zhang, Krzysztof Szarkowicz,
Nagendra Kumar, Melchior Aelmans, Kaushal Tank, Will Jones, Moin
Ahmed, Zheng (Sandy) Zhang, and Donald Eastlake provided thoughtful
comments that improved the readability of the document and found a
good amount of corners where the light failed to shine. Kris Price
was first to mention single router, single arm default
considerations. Jeff Tantsura helped out with some initial thoughts
on BFD interactions while Jeff Haas corrected several misconceptions
about BFD's finer points and helped to improve the security section
around leaf considerations. Artur Makutunowicz pointed out many
possible improvements and acted as a sounding board in regard to
modern protocol implementation techniques RIFT is exploring. Barak
Gafni formalized the problem of partitioned spine and fallen leaves
for the first time clearly on a (clean) napkin in Singapore that led
to the very important part of the specification centered around
multiple ToF planes and negative disaggregation. Igor Gashinsky and
others shared many thoughts on problems encountered in design and
operation of large-scale data center fabrics. Xu Benchong found a
delicate error in the flooding procedures and a schema datatype size
mismatch.
Too many people to mention provided reviews from many directions in
IETF, often pointing to critical defects, sometimes asking for things
again that have been removed by one of the previous reviewers as
objectionable or superfluous, and many times claiming the document
being somewhere on the extremes between too crowded with the obvious
and omitting introduction to cryptic concepts everywhere. The result
is the best editors could do to find a balance of a document guiding
the reader by Section 2 into a specification tight enough to result
in interoperable implementations while at the same time introducing
enough operational context of IP routable fabrics to guarantee a
concise, common language when facing unaccustomed concepts the
protocol relies on. In the process, it was important to not end up
carrying Aesop's donkey of course, so while the result may not be
perceived as perfect by everyone, it should be practically speaking
more than sufficient for everyone that ends up using it in the
future.
Last but not least, Alvaro Retana, John Scudder, Andrew Alston, and
Jim Guichard guided the undertaking as ADs by asking many necessary
procedural and technical questions that did not only improve the
content but also laid out the track towards publication. And Roman
Danyliw is mentioned very last but not least for both his
painstakingly detailed review and improvement of security aspects of
the specification.
Contributors
This work is a product of a list of individuals who are all to be
considered major contributors, independent of the fact whether or not
their name made it to the limited author list.
Tony Przygienda, Ed.
Juniper
Pascal Thubert
Cisco
Bruno Rijsman
Individual
Jordan Head, Ed.
Juniper
Dmitry Afanasiev
Individual
Don Fedyk
LabN
Alia Atlas
Individual
John Drake
Individual
Ilya Vershkov
Nvidia
Authors' Addresses Authors' Addresses
Tony Przygienda (editor) Tony Przygienda (editor)
Juniper Networks Juniper Networks
1137 Innovation Way 1137 Innovation Way
Sunnyvale, CA 94089 Sunnyvale, CA 94089
United States of America United States of America
Email: prz@juniper.net Email: prz@juniper.net
Jordan Head (editor) Jordan Head (editor)
Juniper Networks Juniper Networks
1137 Innovation Way 1137 Innovation Way
Sunnyvale, CA 94089 Sunnyvale, CA 94089
United States of America United States of America
Email: jhead@juniper.net Email: jhead@juniper.net
Alankar Sharma Alankar Sharma
Hudson River Trading Hudson River Trading
United States of America United States of America
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