**Session Date/Time:** 23 Jul 2025 07:30

# 6lo Working Group Session

## Summary

The 6lo Working Group held a productive session covering the status of several working group documents and technical presentations. The meeting was chaired by Carlos Gomez with Eric Vyncke as the responsible AD and Lorenzo as the minute taker. Key discussions centered around the PASA and GAO drafts ready for WGLC, updates to SCHIC compression over IEEE 802.15.4 networks, optical wireless communications, IPv6 Neighbor Discovery prefix registration, and a fast-track fix for the C-flag conflict in EARO.

## Key Discussion Points

### PASA and GAO Draft Status (Luigi)
- **GAO Draft Updates**: Multiple iterations completed addressing Gen-ART and INT-ART reviews from Brian Aberman and Joel Alpern
- **Error Handling**: Clarified terminology for unsupported AIFs - changed from "AIF not supported" to "not used"
- **Bit Field Changes**: 
  - Added C-bit for rover type (from RFC 8505)
  - Renamed confirmation bit to "ratification bit" (R-bit) to avoid conflict
- **IANA Section**: Marked code points as "TBD" due to ongoing allocation changes
- **Review Status**: Both reviewers confirmed their concerns were addressed

### SCHIC Compressed Packets over 802.15.4 (Carlos)
- **Transition Protocol Stack (TPS)**: New section added enabling hybrid approach using 6LoWPAN for IPv6 headers and SCHIC for UDP/CoAP compression
- **SCHIC Stratum Header**: Detailed format provided for joint UDP/CoAP compression, including compression rules for TPS-only devices
- **Route-Over Modes**: Completed Appendix B analyzing three modes:
  - **Straightforward Route-Over (SRO)**: Best for small, static networks
  - **Tunnel-based Route-Over (TRO)**: Optimal for upward-dominant traffic using RPL non-storing mode
  - **Pointer-based Route-Over (PRO)**: Generic approach with greater scalability
- **Technical Concerns**: 
  - Pascal suggested potential need for separate SCHIC stratums between UDP and CoAP layers
  - Discussion on supporting mixed deployments with traditional 6LoWPAN nodes

### IPv6 Packets over Short-Range Optical Wireless Communications (Yoon)
- **Hybrid Compression**: New section on combining 6LoWPAN header compression with SCHIC
- **Capability Signaling**: Uses 6LoWPAN capability bit (S-bit) to indicate SCHIC support
- **Use Cases**: Addresses mixed deployment scenarios and flexible adaptation based on traffic patterns
- **Security Considerations**: Remaining work to be incorporated from co-author's draft

### IPv6 Neighbor Discovery Prefix Registration (Pascal)
- **Status**: Document approved by IESG and in RFC Editor queue
- **Key Features**: Extends 6LoWPAN ND registration to prefixes with overlap detection
- **Future Work Proposal**: 6LoWPAN Unicast Lookup for coexistence with classical IPv6 ND on broadcast networks
- **Working Group Poll**: 7 yes, 1 no, 7 no opinion on pursuing broadcast network extensions

### C-flag Fix in EARO (Adnan)
- **Problem**: Conflict between RFC 8928 (C-flag for crypto ID) and RFC 9685 (P-field occupying same bits)
- **Solution**: Simple fix moving C-flag position and clarifying EARO structure in Neighbor Advertisement
- **Status**: IESG approved in record time (84 days from draft-00 to approval)
- **Process Note**: Eric clarified this required an RFC rather than erratum due to working group consensus issue

## Decisions and Action Items

- **GAO Draft**: Chairs will initiate Working Group Last Call and appoint a shepherd
- **SCHIC 802.15.4 Draft**: 
  - Complete examples in Appendix A
  - Stabilize Section 5 based on feedback
  - Continue alignment with SCHIC architecture evolution
  - Consider separate UDP/CoAP stratum architecture
- **Optical Wireless Draft**: Incorporate security considerations from co-author's work
- **Shepherd Volunteers**: Request for GAO draft shepherd on mailing list

## Next Steps

- Working Group Last Call for GAO draft to begin
- Continued development of SCHIC-related drafts with architecture alignment
- Potential future work on 6LoWPAN ND extensions to broadcast networks based on community interest
- Publication of approved documents (Prefix Registration and C-flag fix) through RFC Editor
- Montreal IETF 123 for next in-person meeting