Session Date/Time: 28 Feb 2024 15:00

CORE

Summary

This interim meeting of the CoRE Working Group covered several key topics: the proposed ALPN registration for CoAP over DTLS, strategies for addressing open issues and errata in CoRE-Kla, the implications of using mDNS for CoAP discovery, and a preliminary schedule for interim meetings post-IETF 119. Decisions were made to proceed with the ALPN registration and to dedicate future interim meetings to resolving CoRE-Kla issues.

Key Discussion Points

ALPN Registration for CoAP/DTLS:
- Christian Bormann announced his intention to request ALPN registration for CoAP over DTLS. This was not done in RFC 7252 as ALPN did not exist then.
- The registration would be for "coap-dtls" and reference RFC 7252 as its specification, clarifying its utility for scenarios like advertising DNS over CoAP servers and fitting with svcb records.
- Michael Koster had provided comments on the mailing list.
- A sense of those present indicated no objections to proceeding with the registration.
CoRE-Kla Errata and Issues:
- Discussion initiated by a recent re-submission of a CoRE-Kla related draft (possibly on "attacks on CoAP") and John Prettejohn's earlier point about blockwise and request tags.
- Christian Bormann indicated no progress on a dedicated document for the blockwise/request tag issue.
- Klaus Hartke noted his recent re-submission of the CoRE-Kla draft to prevent expiration and highlighted the need to address existing errata reports and 25+ issues in the GitHub repository.
- A proposal was made to use future interim meetings to systematically address 1-2 CoRE-Kla issues per meeting.
- It was suggested that specific issues for discussion should be identified and communicated at least a week prior to each interim meeting to allow for preparation and initial mailing list discussion.
mDNS for CoAP Discovery:
- Klaus Hartke raised concerns about the implications of using mDNS for CoAP discovery, particularly the new requirement for constraint devices to implement an mDNS responder to be discoverable by others on the IPv6 link-local network.
- Christian Bormann questioned Ted Lemon's concerns, assuming mDNS mechanisms for reduced broadcast existed.
- Klaus clarified that the document in question suggests implementing both mDNS and Service Registration Protocol (SRP) to achieve less multicasting, which implies a significant code footprint for constraint devices.
- Christian acknowledged previous Mozilla work on this where security was a primary challenge, and that developments like svcb records and TLSA might help address security aspects now.
Post-IETF 119 Interim Meeting Schedule:
- Marco Tiloca presented a preliminary schedule for interim meetings following IETF 119 (Brisbane).
- The plan is to maintain the usual cadence: CoRE meetings on odd weeks, Wednesdays, at the established time.
- Proposed start date: April 10th, 2024.
- The meeting scheduled for May 22nd would be skipped due to the co-occurrence of the IoT Hakon and T2G meeting in Paris.
- This schedule would provide six meetings before IETF 120.
- Christian Bormann confirmed the proposed schedule works for him.

Decisions and Action Items

Decision: Christian Bormann will proceed with the ALPN registration for CoAP over DTLS ("coap-dtls"), referencing RFC 7252.
Decision: The Working Group will dedicate future interim meetings to addressing errata reports and GitHub issues for CoRE-Kla, targeting 1-2 issues per meeting.
Action Item: Chairs to coordinate the selection of specific CoRE-Kla issues for discussion at upcoming interim meetings and announce them in advance.
Action Item: Marco Tiloca to finalize and circulate the proposed post-IETF 119 interim meeting schedule to the Working Group.

Next Steps

Christian Bormann to submit the ALPN registration request for CoAP over DTLS.
Working Group members to prepare for focused discussions on CoRE-Kla issues at future interim meetings.
Chairs to formally announce the interim meeting schedule after internal confirmation.
Continue monitoring and contributing to discussions around mDNS for CoAP discovery, particularly regarding its implications for constraint devices and security considerations.