Session Date/Time: 24 Feb 2022 15:00

CORE

Summary

This interim meeting covered updates on active working group documents: coreconf, href, and coral. Significant progress was reported on coreconf regarding YANG SID file support and a new path forward with yangcatalog.org. The coap-attacks draft was formally split, with the CORE WG focusing on attacks against CoAP, and a call for adoption was initiated. Bill Sylvarajan presented the latest revision of conditional-attributes, leading to discussions on attribute definition and a potential registry. Finally, Kristian Kißling led a discussion on transport indication, outlining a proposed mechanism for advertising resources accessible via both CoAP and CoAP+TCP, and clarifying open issues.

Key Discussion Points

coreconf Update:
- A recent meeting with YANG SIBO authors and area directors discussed yangcatalog.org support for SID files.
- The outcome will be written into a substantial pull request for the coreconf document, likely necessitating another Last Call (possibly an IETF Last Call).
- A suggestion was made to remove the normative reference from yang-sibo to coreconf, which did not meet outright disagreement.
- yangcatalog.org has agreed to support server-side SID, addressing IANA's budget limitations.
href and coral Updates:
- href: Implementations are still being adjusted, a process taking longer than anticipated due to time constraints. An aspirational goal is a revision for IETF 113 that can be considered for Working Group Last Call.
- coral: No specific updates were reported, though work is ongoing.
coap-attacks Document:
- Following discussions at the previous interim, the coap-attacks draft has been formally split.
- The CORE WG document now focuses on attacks against CoAP.
- Parts related to attacks using CoAP (e.g., amplification, formerly section 3) have been moved to a separate document in T2TRG.
conditional-attributes Presentation:
- Bill Sylvarajan presented draft-sylvarajan-core-conditional-attributes-02, submitted prior to the meeting.
- Feedback was incorporated, and three GitHub issues were closed.
- The band attribute's value was changed from a boolean to a query parameter whose presence indicates its use, with further discussion on handling explicit values (e.g., band=0 or band=1).
- The need for a clearer definition of "attributes" (query parameters used in a specific way) was discussed, possibly through a new section that could be referenced by other documents.
- Text on proxies was updated to "should use" Max-Age in security considerations.
- The idea of a conditional attributes registry was introduced to map parameter names, prompting discussion on whether it should be specific to conditional attributes or a more general attributes registry, potentially extending the existing Resource Directory attribute registry.
transport indication Discussion:
- Kristian Kißling presented a proposal for a mechanism to reconcile CoAP servers having resources accessible via both CoAP and CoAP+TCP, allowing clients to switch.
- The proposal leverages existing link format resource announcements, adding a statement that co-hosted resources are available via a proxy (e.g., coap+tcp://address).
- Three key clarification points from reviews were discussed:
  1. URI Aliasing: The mechanism, particularly when omitting the Proxy-URI option, might appear as URI aliasing on the wire, but server and client are aware of the original URI. This should be viewed as a form of compression or context introduction rather than true aliasing. Security considerations should address this.
  2. URI for Proxy Identification: Using URIs like coap+tcp://address to identify a proxy mechanism, distinct from a resource at that host's root. The document could introduce a concept of "proxy described by URI" with a narrow scope.
  3. Use of hosts Relation: The hosts relation (RFC 6690) is used to group resources on the same device, providing an indirection to associate them with a proxy advertised for the device's root (/). Discussion touched on different interpretations of the hosts relation, with the proposal leaning on RFC 6690's definition of an implied relation.
- There was general agreement that this work is important for fulfilling a long-standing promise to support multiple transports in CoAP.

Decisions and Action Items

Decision: The coreconf document will have a pull request incorporating discussion on yangcatalog.org support for SID files.
Decision: The coap-attacks draft in CORE WG will focus on attacks against CoAP, with other aspects moved to T2TRG.
Action Item: A two-week call for adoption will be started on the mailing list for the coap-attacks draft as an informational document in the CORE WG.
Action Item: Bill Sylvarajan (conditional-attributes) to produce a new revision incorporating comments from the meeting (e.g., on attribute definition and registry).
Action Item: Bill Sylvarajan (conditional-attributes) to present the updated draft at IETF 113, aiming for WG Last Call readiness.
Action Item: Kristian Kißling (transport indication) to produce a new revised version of the draft addressing the three clarification points and present it at IETF 113.
Action Item: Bill Sylvarajan and Kristian Kißling to discuss offline the potential for a more general attribute registry and its relation to the Resource Directory's attribute registry.

Next Steps

The CORE WG will hold another interim meeting next week (Wednesday, F-15 UTC).
All active document authors are encouraged to prepare updates for presentation at the IETF 113 two-hour session.