Session Date/Time: 06 Nov 2023 14:30

tcpm

Summary

The TCPM meeting covered working group document status, a re-chartering discussion, and presentations on Generalized ECN, TCP Act Rate Request, EDO implementation experience, TCP AO with TLS, and TCP Fast Window Advance. Key discussion points included the chartering of the working group, especially in relation to CCWG and SCTP, and the potential benefits and drawbacks of each proposed TCP extension.

Key Discussion Points

Re-chartering: Concerns were raised about coordination with SCTP and CCWG, particularly regarding congestion control. It was agreed that CCWG should be the preferred location for congestion control work, even with TCP-specific elements. The charter change was proposed to reflect this and should be submitted by the end of the week.
Generalized ECN (ECN++): Discussion focused on the draft's readiness for working group last call, including potential issues with duplicate acknowledgements and the applicability of STCP considerations. Marcus's concerns regarding ACKs of ACKs needed to be resolved.
TCP Act Rate Request (TAR): Questions were raised about the rationale behind specific values (e.g., "4") for the number of RTTs to wait for feedback. Concerns about how Rwin changes influence TAR decisions were also discussed, suggesting a discussion on the mailing list. Additionally, the interaction with other specifications that trigger ACKs needed clarification.
EDO Implementation: The implementation experience presentation prompted discussion about the interaction of EDO with AO and MPTCP, the impact of long options on windowing, and middlebox behavior (packet fragmentation). Temporary disabling of GRO/GSO when EDO is successfully negotiated was noted as a short-term fix. Feedback on the draft regarding multiple EDO extensions and fallback mechanisms was requested.
TCP AO with TLS: The presentation prompted a discussion about handling partial failures (TLS failing after TCP AO setup) and the interaction between TCP AO key updates and TLS key updates.
TCP Fast Window Advance (FWA): Discussion focused on how the application makes choices to flash any of the data for sender or receiver. Concerns were expressed about the potential for inter-layer protocol communication and a suggestion to combine flags to reduce the overhead.

Decisions and Action Items

Re-chartering: Submit proposed changes to ISG as early as Saturday, pending feedback received by Friday.
Generalized ECN: Address Michael Scharf's concerns regarding SCTP inclusion, and address Marcus's concerns regarding ACK handling, before proceeding to working group last call.
EDO Implementation: Presenters will provide feedback on the implementation to the authors and post it on the mailing list.
Martin: Will spam the TCAM list until someone steps up to co-edit 5681.

Next Steps

Participants should review the proposed re-chartering changes and provide feedback via email by Friday.
Address Marcus's concerns on ECN++ and determine next steps for the document.
Discuss the finer points of the TAR option and it's relationship to RWIN with Carlos and the working group via the mailing list.
Authors of the EDO draft should incorporate the feedback received regarding the limitations and usage with other TCP extensions and how the EDO implementation affects the stack.
Investigate options for potential code point combinations for FWA, and continue discussions on the mailing list.