Session Date/Time: 24 Jul 2023 16:30

LSR Working Group - IETF 117

Summary

The LSR working group meeting covered several draft proposals and ongoing work. Key topics included multipart TLVs, adjacency suppression, prefix unreachable advertisement, advertising IGP offsets, advertising anycast properties, and a proposal for purging originator identification. Discussions revolved around backwards compatibility, incremental deployment, and the applicability of solutions to existing network scenarios.

Key Discussion Points

Multipart TLVs (MPTLV): Les Ginsburg presented the current state of the MPTLV draft, highlighting the need to advertise TLVs larger than 255 bytes due to new features. Backwards compatibility challenges were discussed at length, with alternate proposals involving container TLVs being deemed insufficient.
Adjacency Suppression: Lian presented updates to the adjacency suppression draft, designed to avoid temporary black holes during router restarts. An alternative proposal was presented by Shrada, focusing on changes to the neighbors of the restarting router. Both proposals were discussed, including the need to handle multi-router scenarios and bad LSA requests.
IGP Prefix Unreachable: Peter Chernak presented the IGP prefix unreachable draft, which proposes a way to signal unreachable prefixes using existing protocol mechanisms. There was strong support for adopting this draft as a working group document.
Advertising IGP Offsets: Louis Chen presented a draft for advertising IGP offsets, aiming to reduce IGP advertisement overhead. Concerns were raised regarding the need to wait for the TEAS working group direction before proceeding. Additionally, the complexity of the proposed solution and potential alternative approaches were discussed.
Anycast Property Advertisement: presented on the anycast property advertisement draft, which proposes a way to identify anycast prefixes. The need for use cases to be clearly defined in the draft was emphasized.
Purge Originator Identification: Shudh Wang presented a proposal for identifying the originator of purge LSAs. Concerns were raised about the practicality of the solution and potential negative impacts on network stability.
Temporal Links: Weibo presented a proposal to advertise Temporal Links in order to reflect scheduled link availability. Concerns were raised about the practicality of the solution due to the reliance on accurate clock synchronization on all nodes.

Decisions and Action Items

IGP Prefix Unreachable: The working group will hold an adoption call for the IGP prefix unreachable draft on the mailing list.
Multipart TLVs (MPTLV): Continue discussion about feature support and/or capability advertisement on the mailing list.
Adjacency Suppression: Continue discussion and consider merging proposals for adjacency suppression on the mailing list.
Advertising IGP Offsets: Determine direction with TEAS working group before further work.
Anycast Property Advertisement: Add more Use Cases into the draft to motivate the flag usage.

Next Steps

Authors of the adjacency suppression drafts should consider merging their proposals.
Authors of anycast advertisement should detail the use cases.
The Advertising IGP Offsets is pending TEAS working group direction.
Continue discussion of other topics on the mailing list.