6MAN

Summary

The 6MAN Working Group met at IETF 119 in Brisbane. The session was chaired by Jen Linkova and Bob Hinden (both participating remotely), with Erik Vyncke acting as the on-site chair. The meeting marked a leadership transition as Eric Kline stepped down as the responsible Area Director (AD), with Erik Vyncke taking over the role. The agenda covered four working group documents and five individual presentations, focusing on neighbor discovery, extension header security, and routing-related ICMP behavior.

Key Discussion Points

Introduction and Document Status

AD Transition: Eric Kline is finishing his term; Erik Vyncke is the new responsible AD for 6MAN.
MISREF Issues: Several drafts (including draft-ietf-6man-rfc6724-bis) are held in the RFC Editor Queue due to a normative reference to a SNAC draft. The ADs and chairs discussed potentially changing the SNAC reference to "informative" to unblock the queue.
draft-ietf-6man-slaac-renum: Lorenzo Colitti raised concerns that the current draft could cause battery drain on mobile devices by sending too many Router Advertisements (RAs) during renumbering. The draft will be returned to the working group for revision.

Working Group Drafts

YANG Data Model for IPv6 Neighbor Discovery
- Presenter: Fan Yang (on behalf of draft-ietf-6man-ipv6-neighbor-discovery-yang)
- Discussion: Updates based on YANG Doctor reviews were presented, including the removal of certain dynamic resolution leaves and simplification of Proxy NA. The authors requested a Working Group Last Call (WGLC).
IPv6 Query for Enabled In-situ OAM Capabilities
- Presenter: Xiao Min (on behalf of draft-ietf-6man-icmpv6-ioam-conf-state)
- Discussion: The draft’s foundation has moved from RFC 4620 to draft-ietf-intarea-icmp-query. The working group will wait for the INTAREA draft to progress before initiating WGLC.
Carrying Network Resource (NR) related Information in IPv6 Extension Header
- Presenter: Jie Dong (on behalf of draft-ietf-6man-enhanced-vpn-vtn-id)
- Discussion: Debate occurred regarding the fixed 32-bit length of the NRP selector ID. Greg Mirsky and Erik Vyncke suggested that 6MAN should perhaps defer the length definition to other groups (like TEAS or MPLS), though the authors noted the current encoding is extensible.
IPv6 Node Requirements
- Presenter: Tim Chown (on behalf of draft-ietf-6man-rfc8504-bis)
- Discussion: The authors plan to revert the Extension Header (EH) limit text to the original RFC 8504 language since the dedicated EH limits draft did not progress. Updates regarding PMTUD (RFC 8899) and DNS section clarifications were discussed.

Individual Presentations

The IPv6 Loopback Address Prefix
- Presenter: Jen Linkova (on behalf of authors)
- Discussion: The proposal to expand the loopback prefix to ::/96 met significant resistance. Brian Carpenter and Jen Linkova expressed concerns about overlapping with the unspecified address (::). Lorenzo Colitti noted the utility of multiple loopback addresses but questioned the specific prefix choice.
Addressing Extension Header Vulnerabilities
- Presenter: Tom Herbert
- Discussion: This covered four distinct ideas: enforcing EH ordering/occurrence, "obsoleting" certain EHs on the public internet, removing EHs at egress, and restricting Destination Options locations.
- Feedback: Lorenzo Colitti noted that fragmentation cannot be deprecated because DNS relies on it. Ron Bonica supported enforcing ordering/occurrence rules as "MUSTs" but opposed middlebox modification/removal of headers.
Updates to DNS64 Functionality Advertisement for DNS RA Option
- Presenter: Chenhao
- Discussion: The proposal adds a "T" flag to RDNSS to indicate DNS64 capability. Jordi Palet and Lorenzo Colitti argued that existing tools (like separate APNs or ipv4only.arpa lookups) already solve the stated use cases without protocol changes.
ICMP Error Handling for VPNs in SRv6 Networks
- Presenter: Balaji Venkat Venkataswami
- Discussion: The draft addresses how to return ICMP errors to VPN endpoints in an SRv6 network without requiring P-nodes to be VPN-aware. Suresh Krishnan suggested the work might better belong in the SPRING WG. Ron Bonica supported the technical approach of not involving the tunnel egress.

Decisions and Action Items

draft-ietf-6man-slaac-renum: Authors must revise the draft to address battery consumption concerns (specifically the frequency/count of RAs sent during renumbering) before advancing.
draft-ietf-6man-rfc8504-bis: Authors to update references (including RFC 8899) and finalize the revert of EH limit text to match RFC 8504.
draft-ietf-6man-yang-data-model-for-ipv6-neighbor-discovery: Chairs will initiate WGLC following the meeting.
SNAC MISREF: ADs (Erik Vyncke and Eric Kline) will investigate if the normative dependency on the SNAC draft can be downgraded to informative to unblock draft-ietf-6man-rfc6724-bis and the RA-Flag draft.

Next Steps

Liaison Statement: David Schinazi and Suresh Krishnan will coordinate a liaison statement to the IEEE regarding draft-ietf-6man-ieee80211-fms.
draft-ietf-6man-enhanced-vpn-vtn-id: Continued discussion on the mailing list regarding ID length flexibility.
Individual Drafts: Authors of the Loopback and DNS64 RA drafts were encouraged to refine their problem statements and consult the V6OPS working group for operational consensus.
SRv6 ICMP: Chairs from 6MAN and SPRING will discuss the appropriate home for this work.

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