Session Date/Time: 05 Nov 2024 09:30

ccwg

Summary

The CCWG session at IETF 121 covered a range of topics including updates on congestion control algorithms, the process for contributing changes, adoption calls, and future work items. Key discussions revolved around BBRv3, rate-limited senders, search algorithms, and Screen v2. A significant portion of the meeting was dedicated to soliciting feedback on how the working group can support individuals who want to contribute ideas but may not have the resources for large-scale testing.

Key Discussion Points

Contribution Model for Congestion Control Algorithms: Discussion on how to contribute changes to congestion control algorithms, focusing on enabling participation without requiring extensive resources for testing. The proposal involves escalating steps, from filing issues to providing pull requests and test data.
Test Cases and Evaluation Suites: The need for standardized test cases, particularly for emerging scenarios like LEO satellite networks and cellular networks, was discussed. There were differing opinions as to whether this work should be undertaken in CCWG or IRTF
BBRv3 Updates: An overview of the latest changes to the BBR congestion control draft, including renaming, conversion to Markdown, and clarification of the algorithm. Open issues regarding drain gain, ACF phase removal, and generalization for Quick were discussed.
Rate-Limited Senders: Presentation on the "Increase Congestion Window When Sender is Rate Limited" draft, focusing on limiting the growth of the congestion window when flight size is smaller than the congestion window.
Search Algorithm: An update on the Search algorithm, a new slow start algorithm for TCP and Quick, with a particular focus on reducing per-flow memory usage and handling rate-limited flows.
Screen v2: Overview of recent updates to the Screen v2 draft, a media congestion control algorithm.

Decisions and Action Items

BBRv3: Participants were encouraged to review the latest version of the BBR draft and file issues on GitHub. An issue should be created to discuss ECN behaviour.
Rate-Limited Senders: The working group will proceed with an adoption call on the mailing list.
Search Algorithm: The working group will proceed with an adoption call on the mailing list.
Screen v2: There was a discussion on whether the working group had the bandwidth to work on Screen v2 simultaneously with other items. There wasn't a strong interest to work on the document at this time.

Next Steps

Conduct adoption calls on the mailing list for "Rate-Limited Senders" and the "Search Algorithm".
Continue discussions on the mailing list and GitHub regarding open issues and potential contributions to BBRv3, Rate-Limited Senders, Search and other potential topics.
Explore the feasibility and potential location of standardized test cases for congestion control algorithms in new network environments.