tsvwg

Summary

This meeting of the Transport Area Working Group (tsvwg) covered several topics, including updates on existing drafts, a proposal for using GitHub, and presentations on media headway extensions for wireless networks and datagram path MTU discovery for UDP options. Key discussions focused on the potential use of UDP options, especially regarding encryption and authentication.

Key Discussion Points

GitHub Adoption: The chairs proposed using GitHub for draft management, including issue tracking and pull requests. There were no objections to this approach, especially given it was not a forced march.
Media Headway Extensions for Wireless (John):
- The draft proposes a UDP option ("med") to provide information (priority, delay, burst size) to wireless routers for shaping and scheduling encrypted media traffic.
- Discussions revolved around the suitability of UDP options versus alternatives like DSCP, IPv6 flow label, and IPv6 hop-by-hop/destination options. Concerns were raised about the performance implications of using UDP options and the mutability of the IPv6 flow label.
- It was clarified that using two flow labels defines two distinct flows. Concerns were raised regarding architectural correctness when intermediate nodes inspect data.
- Potential for explicit communication between information creator and consumer in 3GPP was raised.
Datagram Path MTU Discovery for UDP Options:
- Status update on the draft, indicating no pending issues. Progress is dependent on the completion of the UDP options draft.
- Discussion arose about the applications of UDP options, particularly those involving moving encrypted information to clear headers. Concerns were raised about the security and architectural implications of such approaches.
- A proposed tenant suggested that UDP options should never be attached to encrypted UDP packets. This sparked debate about the potential for creating blocking points to deployment and the ability of networks to modify packets.
- The risk of network providers dropping all packets with UDP options in response to denial-of-service attacks was raised.
- Discussion on fragmentation, encryption and authentication options. Encryption and Authentication options are currently immature and not getting sufficient reviews.

Decisions and Action Items

GitHub Adoption: Proceed with setting up GitHub repositories for adopted drafts, focusing on issue tracking and pull request workflows. Editors of existing drafts will be invited to move their drafts to the TSBWG GitHub organization.
Media Headway Extensions for Wireless: The presenter will consider the feedback received, especially regarding alternative options and the use of flow labels. Further discussion to occur on the mailing list.
UDP Options: The chairs will speak to the editor (Joe) and the Area Director about progressing the UDP options draft. Encourage further review and discussion on the mailing list.
UDP Options Encryption and Authentication: Further discussion on the mailing list to determine if the encryption part should be worked on and how should the authentication part be handled (in a single document or split out)

Next Steps

Implement the GitHub repository approach.
Continue discussions on the mailing list regarding the media headway extensions and UDP options drafts.
Address open issues related to UDP options encryption and authentication through mailing list discussion and editor coordination.

Session Date/Time: 27 Jul 2023 16:30

tsvwg Meeting Minutes

Summary

This meeting covered a range of topics related to transport protocols, including congestion control, multipath TCP, and security considerations. Key discussions revolved around Careful Resumption, MPDCCP, DTLS and SCTP security, and the use of UDP trailers for traffic prioritization. The group considered various proposals and provided feedback to the authors, with some documents nearing readiness for working group last call.

Key Discussion Points

Careful Resumption:
- Presented updates on the Careful Resumption congestion control algorithm, including NS3 and Linux implementations.
- Discussed the trade-offs between pacing strategies and the potential benefits (around 4 RTTs).
- Addressed the challenge of determining when to cache BDP and RTT information appropriately for resumption.
- The need to decaying information after silence.
- The impact of receiver auto-tuning and flow control on jump performance in TCP vs. QUIC.
MPDCCP:
- Discussed optimizations to the handshaking procedure, specifically replacing derived tokens with connection identifiers to avoid collision checks.
- Addressed the removal of TA information in the final leg of the initial handshake.
- The security principle is not changed because of the Hmac authentication.
DTLS and SCTP Security:
- Explored different approaches for securing SCTP traffic, including DTLS over SCTP and a new "cryptoshank" proposal that protects individual SCTP packets.
- Addressed concerns about the availability of DTLS features and implementation challenges.
- Discussed the requirements from 3GPP.
- Highlighted the importance of rekeying robustness and avoiding data loss during key rotation.
SCTP Checksum Extension:
- Discussed a simple extension to SCTP that allows receivers to signal acceptance of packets with incorrect checksums when an alternate error detection method is in place (e.g., DTLS).
- Considered the implications for IPv6 and the need for clear guidance in the document.
- The checksome is running over IPv6 you don't have an alternate method.
L4S Experimental Deployment:
- Reported on the ongoing L4S experimental deployment in Comcast's network, including experiences with ECN marking and DSCP leakage.
- Shared the high level of customer interest in L4S testing.
- The testing running July through September.
Operational Guidance for L4S with Classic ECN:
- Focused on a draft providing guidance on how L4S interacts with classic ECN, primarily on RFC 3168 Bottlenecks.
- Desire to keep the guidance draft open to incorporate implementation experiences.
NQB Draft:
- Review and discussion of NQB draft.
- Adding more guidance on implementation of a traffic protection function.
- Lowered upper bound of application data rates from 1MBps to 500KBps.
UDP Trailers with Encrypted Transports:
- Presented a proposal to use UDP trailers for signaling traffic prioritization information to access networks.
- Addressed privacy concerns.

Decisions and Action Items

MPDCCP: Editors to revise the draft to incorporate changes discussed.
DTLS and SCTP Security: Hold an interim meeting on September 19th at 1600 CET to further discuss the proposals and requirements. The chairs will prepare chartered items for this work by the next IETF.
SCTP Checksum Extension: Editors to revise the draft to clarify IPv6 implications and address other minor comments.
NQB Draft: Editors to address issues and put new revision with new text.

Next Steps

MPDCCP: Expect revised document in 1-2 revisions followed by a working group last call.
DTLS and SCTP Security: Prepare for and participate in the interim meeting.
SCTP Checksum Extension: Address comments from the list and prepare a new revision for a working group last call.
L4S Experimental Deployment: Continue testing and analysis, share results at IETF 118 in Prague.
UDP Trailers: Prepare revisions clarifying security and network architecture concerns.