**Session Date/Time:** 20 Mar 2025 02:30

# snac

## Summary

The SNAC working group meeting focused on the draft for Stub Network Auto Configuration (SNAC) simple, specifically addressing the issue of multiple prefixes delegated via DHCPv6. Discussion centered on selecting the appropriate prefix (ULA vs. GUA) for constrained networks and the implications for routing and network stability. Additionally, the group reviewed open issues in the draft, with a focus on clarifying normative language and addressing comments from Fernando Gont. The group decided to schedule interim meetings to continue work.

## Key Discussion Points

*   **Multiple Prefix Delegation:**
    *   Consideration of whether to select one OSNR prefix or pass all available prefixes to the stub network.
    *   Discussion of selection criteria for prefixes (ULA vs. GUA, prefix length, lifetime).
    *   The importance of selecting the same prefix if multiple stub routers are present on the same network.
    *   A GUA is preferred, with hysteresis to prevent rapid switching between prefixes due to temporary outages.
*   **ULA vs. GUA Selection:**
    *   Arguments for both ULA (stability, local communication) and GUA (global connectivity).
    *   Suggestion to allow users a knob to indicate whether IOT devices should have global connectivity or not, based on security considerations.
    *   Consideration of defaults, and the possibility of different behaviours per network technology.
*   **Review of Open Issues:**
    *   Clarification of defaults regarding zeroed fields to use the values specified in RFC 4861 for router advertisements.
    *   The group concluded that a RA option should be a 'must' within one packet, with exception considered on a case-by-case basis.
    *   The group clarified that appendix values are normative to specific use-cases in the standard. The group will review consistancy between the document and its appendices.
    *   Discussion on interaction with RA Guard and DHCPv6 Guard, and potential for packet loss.
    *   Action to add explanation in Appendix A about the implications of RA Guard.

## Decisions and Action Items

*   **Action Item:** Ted will add a global note stating that defaults communicating default will be used wherever applicable.
*   **Action Item:** Ted to fix the ULA vs. GUA terminology.
*   **Action Item:** Ted to adjust the text in Section 6 to match the Nat 64 state machine
*   **Decision:** Schedule interim meetings every other week to continue working group progress.
*   **Action Item:** Add an implementation section, requesting participants to contribute their SNAC implementations.
*   **Action Item:** Ted will add text to explain hairpinning in the appendices.
*   **Action Item:** Tim Winters (Shepherd) will address hairpinning in updates.

## Next Steps

*   Continue discussion on the mailing list, especially regarding the selection between ULA and GUA.
*   Address the action items identified during the meeting.
*   Schedule and announce interim working group meetings.