Session Date/Time: 26 Jul 2024 16:30

LSR Session

Summary

The LSR (Link State Routing) session at IETF covered several topics, including updates on existing working group documents, adoption calls for new drafts, and presentations on various proposals for OSPF and ISIS improvements. A significant portion of the session was dedicated to discussing a proposed update to a flooding reduction draft, sparking debate about scope and architectural design. Other key topics included fragment timestamping, OSPF database exchange optimization, intra-domain source address validation, and extensions for SRv6 and SR policies.

Key Discussion Points

Flooding Reduction Draft: Extensive discussion about the addition of a new control mechanism to determine how flooding algorithms are enabled. Les Ginsberg argued that this is logically independent from the flooding algorithm itself and should be a separate draft. Tony P defended the coupling due to customer requirements. There was a show of hands to gauge the room's preference for splitting the draft.
Fragment Timestamping: Tony P presented a proposal for fragment timestamping. Tony Lee suggested using a Unix timestamp. Les Ginsberg questioned the usefulness for a controller versus router-based use case. Clarification on use cases and warnings against using the timestamp for control plane behavior were discussed.
Optimized OSPF Database Exchange: Discussion on a draft aiming to improve OSPF database exchange, particularly after router restarts. Optimizations related to tracking neighbors and limiting the scope of stale LSA tracking were presented. Concerns about stale LSAs being used in the domain were addressed.
Intra-domain Source Address Validation (SAVNET): Presentation on an IGP-based method for intra-domain SAVNET. The use of existing administrative tags versus defining new subnet tag sub-TLVs was discussed. Tony P raised questions on how this proposal interacted with BGP and preferences.
Flex Algo and Multicast: Les Ginsberg presented an extension to Flex Algo to support multicast with asymmetric metrics. The need for a common data plane between source and receivers was highlighted. The applicability of this approach for PIM and other multicast technologies was brought up.
SRv6 SID Advertisement Optimization: Presentation on a method to reduce the number of LSP advertisements for SRv6 Flex Algo. Concerns were raised about the complexity and use cases.

Decisions and Action Items

Flooding Reduction Draft: The chairs will take the show of hands and mailing list discussion into account and make a call on rough consensus regarding splitting the draft.
Fragment Timestamping: Tony P will clarify use cases and add text warning against using timestamps for control plane behavior. Tony P will consider feedback and continue discussion of timestamp resolution and format.
Optimized OSPF Database Exchange: Leon from China Mobile will add a specific scenario to the mailing list to discuss a potential issue with the proposal.
All authors to take into account feedback from the working group on their presented drafts.

Next Steps

Continue discussion of open issues on the mailing list.
Authors to update their drafts based on feedback received.
The chairs will assess consensus on the flooding reduction draft and provide guidance.
Working group will consider adoption calls for the PIX Young model and Flexiago with link loss drafts.