**Session Date/Time:** 22 Jul 2025 12:30

# 6man Session

## Summary

The 6man working group session covered document status updates, hackathon results on IPv6 address selection rules, IPv6 node requirements updates, and several technical presentations. Key topics included IPv6 extension header limits, rule 5.5 implementation testing, node requirements for IPv6-only networks, and various protocol improvements. The session highlighted ongoing challenges with IPv6 deployment and multihoming, particularly around proper source address selection and routing behavior.

## Key Discussion Points

### Document Status Updates
- Two RFCs published: DHCP prefix delegation to clients and deprecation of IPv6 route
- Multiple documents in RFC Editor queue, including snack router alert and IPv6 zone identifiers
- Extension header limits document (draft-ietf-6man-eh-limits) has five IESG discuss positions and may need to return to working group
- ULA document (RFC 6724) close to approval with minor text fixes needed

### IPv6 Address Selection Testing Results (Hackathon Report)
- Comprehensive testing of RFC 3484 Rule 5.5 and RFC 8028 across multiple platforms
- Apple and Windows implement Rule 5.5 correctly; Linux does not
- Neither Apple nor Windows implement RFC 8028 properly for topology changes
- Network Manager's ECMP behavior breaks IPv6 multihoming assumptions
- Apple devices have a minor bug with router deprecation that self-corrects

### IPv6 Node Requirements Updates (RFC 8504bis)
- Adding mandatory support for both PMTU discovery and PLPMTU discovery
- Removing extension header processing text, delegating to separate document
- Considering mandatory RFC 8028 implementation for proper multihoming
- Planning IPv6-only network section with requirements for local synthesis, PREF64 option
- Discussion on router solicitation requirements vs RFC 4861 inconsistency

### Technical Presentations
- **Reflection Utility**: ICMP-based diagnostic tool in working group last call
- **Off-link Prefix Issues**: Problems with redirect messages and neighbor discovery in isolated networks
- **IPv6 Aggregate Header Limits**: Problem statement for handling large extension headers in SRv6 networks
- **ICMP Error Handling in SRv6**: Uniform model for ICMP error propagation in service provider VPNs
- **WiFi Multicast Issues**: Proposal to mandate IEEE 802.11 Flexible Multicast Service for IPv6

## Decisions and Action Items

### Extension Header Limits
- Document will return to working group due to unresolvable IESG discusses
- Need to separate node protection requirements from transmission limits
- Authors to address discuss comments and potentially restructure document

### IPv6 Node Requirements
- Add PLPMTU discovery as mandatory requirement
- Include DHCP-PD per client awareness
- Consider RFC 8028 as mandatory for multihoming support
- Create new draft to fix RFC 4861 router solicitation inconsistency
- Develop IPv6-only network section for next revision

### Implementation Issues
- Network Manager developers to be contacted about ECMP routing problems
- Apple bug report submitted for router deprecation issue
- Linux Rule 5.5 patch needs cleanup and upstream submission

## Next Steps

- Continue extension header limits discussion on mailing list
- RFC 6724bis final review and approval process
- IPv6 node requirements working group last call preparation
- Reflection utility working group last call completion
- WiFi Alliance engagement regarding mandatory Flexible Multicast Service
- Development of IPv6 multihoming deployment guidance document
- Off-link prefix operational guidance document development
- Cross-working group coordination for SRv6 ICMP error handling

The session demonstrated significant progress on IPv6 deployment challenges while identifying areas requiring continued standardization and implementation work, particularly around multihoming and IPv6-only network operations.