| rfc9815v2.txt | rfc9815.txt | |||
|---|---|---|---|---|
| Internet Engineering Task Force (IETF) K. Patel | Internet Engineering Task Force (IETF) K. Patel | |||
| Request for Comments: 9815 A. Lindem | Request for Comments: 9815 A. Lindem | |||
| Category: Standards Track Arrcus, Inc. | Category: Standards Track Arrcus, Inc. | |||
| ISSN: 2070-1721 S. Zandi | ISSN: 2070-1721 S. Zandi | |||
| W. Henderickx | W. Henderickx | |||
| Nokia | Nokia | |||
| July 2025 | July 2025 | |||
| BGP Link-State Shortest Path First (SPF) Routing | BGP Link-State Shortest Path First (SPF) Routing | |||
| Abstract | Abstract | |||
| Many Massively Scaled Data Centers (MSDCs) have converged on | Many Massively Scaled Data Centers (MSDCs) have converged on | |||
| simplified Layer 3 (L3) routing. Furthermore, requirements for | simplified Layer 3 (L3) routing. Furthermore, requirements for | |||
| operational simplicity have led many of these MSDCs to converge on | operational simplicity have led many of these MSDCs to converge on | |||
| BGP as their single routing protocol for both fabric routing and Data | BGP as their single routing protocol for both fabric routing and Data | |||
| Center Interconnect (DCI) routing. This document describes | Center Interconnect (DCI) routing. This document describes | |||
| extensions to BGP for use with BGP - Link State (BGP-LS) distribution | extensions to BGP for use with BGP Link State (BGP-LS) distribution | |||
| and the Shortest Path First (SPF) algorithm. In doing this, it | and the Shortest Path First (SPF) algorithm. In doing this, it | |||
| allows BGP to be efficiently used as both the underlay protocol and | allows BGP to be efficiently used as both the underlay protocol and | |||
| the overlay protocol in MSDCs. | the overlay protocol in MSDCs. | |||
| Status of This Memo | Status of This Memo | |||
| This is an Internet Standards Track document. | This is an Internet Standards Track document. | |||
| This document is a product of the Internet Engineering Task Force | This document is a product of the Internet Engineering Task Force | |||
| (IETF). It represents the consensus of the IETF community. It has | (IETF). It represents the consensus of the IETF community. It has | |||
| skipping to change at line 62 ¶ | skipping to change at line 62 ¶ | |||
| in the Revised BSD License. | in the Revised BSD License. | |||
| Table of Contents | Table of Contents | |||
| 1. Introduction | 1. Introduction | |||
| 1.1. Terminology | 1.1. Terminology | |||
| 1.2. Requirements Language | 1.2. Requirements Language | |||
| 1.3. BGP Shortest Path First (SPF) Motivation | 1.3. BGP Shortest Path First (SPF) Motivation | |||
| 1.4. Document Overview | 1.4. Document Overview | |||
| 2. Base BGP Protocol Relationship | 2. Base BGP Protocol Relationship | |||
| 3. BGP - Link State (BGP-LS) Relationship | 3. BGP Link State (BGP-LS) Relationship | |||
| 4. BGP SPF Peering Models | 4. BGP SPF Peering Models | |||
| 4.1. BGP Single-Hop Peering on Network Node Connections | 4.1. BGP Single-Hop Peering on Network Node Connections | |||
| 4.2. BGP Peering Between Directly Connected Nodes | 4.2. BGP Peering Between Directly Connected Nodes | |||
| 4.3. BGP Peering in Route-Reflector or Controller Topology | 4.3. BGP Peering in Route-Reflector or Controller Topology | |||
| 5. BGP Shortest Path First (SPF) Routing Protocol Extensions | 5. BGP Shortest Path First (SPF) Routing Protocol Extensions | |||
| 5.1. BGP-LS SPF SAFI | 5.1. BGP-LS SPF SAFI | |||
| 5.1.1. BGP-LS-SPF NLRI TLVs | 5.1.1. BGP-LS-SPF NLRI TLVs | |||
| 5.1.2. BGP-LS Attribute | 5.1.2. BGP-LS Attribute | |||
| 5.2. Extensions to BGP-LS | 5.2. Extensions to BGP-LS | |||
| 5.2.1. Node NLRI Usage | 5.2.1. Node NLRI Usage | |||
| skipping to change at line 252 ¶ | skipping to change at line 252 ¶ | |||
| topologies while sharing the same NLRI. | topologies while sharing the same NLRI. | |||
| Finally, the BGP SPF topology can be used as an underlay for other | Finally, the BGP SPF topology can be used as an underlay for other | |||
| BGP SAFIs (using the existing model) and obtain all the above | BGP SAFIs (using the existing model) and obtain all the above | |||
| advantages. | advantages. | |||
| 1.4. Document Overview | 1.4. Document Overview | |||
| This document begins with Section 2 defining the precise relationship | This document begins with Section 2 defining the precise relationship | |||
| that BGP SPF has with the base BGP protocol [RFC4271] and Section 3 | that BGP SPF has with the base BGP protocol [RFC4271] and Section 3 | |||
| defining the BGP - Link State (BGP-LS) extensions [RFC9552]. The BGP | defining the BGP Link State (BGP-LS) extensions [RFC9552]. The BGP | |||
| peering models as well as their respective trade-offs are then | peering models as well as their respective trade-offs are then | |||
| discussed in Section 4. The remaining sections, which make up the | discussed in Section 4. The remaining sections, which make up the | |||
| bulk of the document, define the protocol enhancements necessary to | bulk of the document, define the protocol enhancements necessary to | |||
| support BGP SPF including BGP-LS extensions (Section 5), replacement | support BGP SPF including BGP-LS extensions (Section 5), replacement | |||
| of the base BGP Decision Process with the SPF computation | of the base BGP Decision Process with the SPF computation | |||
| (Section 6), and BGP SPF error handling (Section 7). | (Section 6), and BGP SPF error handling (Section 7). | |||
| 2. Base BGP Protocol Relationship | 2. Base BGP Protocol Relationship | |||
| With the exception of the Decision Process, BGP SPF extensions | With the exception of the Decision Process, BGP SPF extensions | |||
| skipping to change at line 299 ¶ | skipping to change at line 299 ¶ | |||
| specified in phase 3 of the base BGP Decision Process. Multiple | specified in phase 3 of the base BGP Decision Process. Multiple | |||
| peering models are supported, as specified in Section 4. | peering models are supported, as specified in Section 4. | |||
| 2. Determining the degree of preference for BGP routes, as described | 2. Determining the degree of preference for BGP routes, as described | |||
| in phase 1 of the base BGP Decision Process, is replaced with the | in phase 1 of the base BGP Decision Process, is replaced with the | |||
| mechanisms in Section 6.1 for the SPF calculation. | mechanisms in Section 6.1 for the SPF calculation. | |||
| 3. Phase 2 of the base BGP protocol Decision Process is replaced | 3. Phase 2 of the base BGP protocol Decision Process is replaced | |||
| with the SPF algorithm, also known as the Dijkstra algorithm. | with the SPF algorithm, also known as the Dijkstra algorithm. | |||
| 3. BGP - Link State (BGP-LS) Relationship | 3. BGP Link State (BGP-LS) Relationship | |||
| [RFC9552] describes a mechanism by which link-state and Traffic | [RFC9552] describes a mechanism by which link-state and Traffic | |||
| Engineering (TE) information can be collected from networks and | Engineering (TE) information can be collected from networks and | |||
| shared with external entities using BGP. This is achieved by | shared with external entities using BGP. This is achieved by | |||
| defining NLRIs that are advertised using the BGP-LS AFI. The BGP-LS | defining NLRIs that are advertised using the BGP-LS AFI. The BGP-LS | |||
| extensions defined in [RFC9552] make use of the Decision Process | extensions defined in [RFC9552] make use of the Decision Process | |||
| defined in [RFC4271]. Rather than reusing the BGP-LS SAFI, the BGP- | defined in [RFC4271]. Rather than reusing the BGP-LS SAFI, the BGP- | |||
| LS-SPF SAFI (Section 5.1) is introduced to ensure backward | LS-SPF SAFI (Section 5.1) is introduced to ensure backward | |||
| compatibility for BGP-LS SAFI usage. | compatibility for BGP-LS SAFI usage. | |||
| skipping to change at line 1714 ¶ | skipping to change at line 1714 ¶ | |||
| DOI 10.17487/RFC7911, July 2016, | DOI 10.17487/RFC7911, July 2016, | |||
| <https://www.rfc-editor.org/info/rfc7911>. | <https://www.rfc-editor.org/info/rfc7911>. | |||
| [RFC7938] Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of | [RFC7938] Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of | |||
| BGP for Routing in Large-Scale Data Centers", RFC 7938, | BGP for Routing in Large-Scale Data Centers", RFC 7938, | |||
| DOI 10.17487/RFC7938, August 2016, | DOI 10.17487/RFC7938, August 2016, | |||
| <https://www.rfc-editor.org/info/rfc7938>. | <https://www.rfc-editor.org/info/rfc7938>. | |||
| [RFC9816] Patel, K., Lindem, A., Zandi, S., Dawra, G., and J. Dong, | [RFC9816] Patel, K., Lindem, A., Zandi, S., Dawra, G., and J. Dong, | |||
| "Usage and Applicability of BGP Link-State Shortest Path | "Usage and Applicability of BGP Link-State Shortest Path | |||
| Routing (BGP-SPF) in Data Centers", RFC 9816, | First (SPF) Routing in Data Centers", RFC 9816, | |||
| DOI 10.17487/RFC9816, July 2025, | DOI 10.17487/RFC9816, July 2025, | |||
| <https://www.rfc-editor.org/info/rfc9816>. | <https://www.rfc-editor.org/info/rfc9816>. | |||
| Acknowledgements | Acknowledgements | |||
| The authors would like to thank Sue Hares, Jorge Rabadan, Boris | The authors would like to thank Sue Hares, Jorge Rabadan, Boris | |||
| Hassanov, Dan Frost, Matt Anderson, Fred Baker, Lukas Krattiger, | Hassanov, Dan Frost, Matt Anderson, Fred Baker, Lukas Krattiger, | |||
| Yingzhen Qu, and Haibo Wang for their reviews and comments. Thanks | Yingzhen Qu, and Haibo Wang for their reviews and comments. Thanks | |||
| to Pushpasis Sarkar for discussions on preventing a BGP SPF router | to Pushpasis Sarkar for discussions on preventing a BGP SPF router | |||
| from being used for non-local traffic (i.e., transit traffic). | from being used for non-local traffic (i.e., transit traffic). | |||
| skipping to change at line 1789 ¶ | skipping to change at line 1789 ¶ | |||
| Email: keyur@arrcus.com | Email: keyur@arrcus.com | |||
| Acee Lindem | Acee Lindem | |||
| Arrcus, Inc. | Arrcus, Inc. | |||
| 301 Midenhall Way | 301 Midenhall Way | |||
| Cary, NC 27513 | Cary, NC 27513 | |||
| United States of America | United States of America | |||
| Email: acee.ietf@gmail.com | Email: acee.ietf@gmail.com | |||
| Shawn Zandi | Shawn Zandi | |||
| Email: shafagh@shafagh.com | ||||
| 222 2nd Street | ||||
| San Francisco, CA 94105 | ||||
| United States of America | ||||
| Email: szandi@linkedin.com | ||||
| Wim Henderickx | Wim Henderickx | |||
| Nokia | Nokia | |||
| copernicuslaan 50 | copernicuslaan 50 | |||
| 2018 Antwerp | 2018 Antwerp | |||
| Belgium | Belgium | |||
| Email: wim.henderickx@nokia.com | Email: wim.henderickx@nokia.com | |||
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| 11 lines changed or deleted | 7 lines changed or added | |||
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