**Session Date/Time:** 25 Jul 2025 07:30

# snac

## Summary

The snac working group met to discuss a new presentation on Full DNSD Service Infrastructure and to review active issues on their current draft. Matthew from Silicon Labs presented a solution for infrastructure-based DNS service discovery to reduce MDNS impact on networks and improve battery performance for Wi-Fi devices. The group then conducted an extensive review of open GitHub issues and pull requests for their specification document, discussing technical details around prefix delegation, guest networks, and various editorial improvements.

## Key Discussion Points

### Full DNSD Service Infrastructure Presentation

- **Problem Statement**: MDNS creates network congestion and battery drain issues for Wi-Fi devices
- **Proposed Solution**: Infrastructure-based DNS service with four components:
  - DNS zone for DNSD information storage
  - SRP (Service Registration Protocol) service for adding/updating services
  - Advertising proxy for MDNS backwards compatibility
  - Discovery proxy for MDNS device discovery
- **Discovery Mechanism**: Uses Router Advertisement (RA) with new RA option to advertise service availability
- **Router Lifetime Usage**: Differentiates between infrastructure routers (non-zero lifetime) and snac routers (zero lifetime)

### Technical Discussions

- **Working Group Scope**: Discussion on whether this work belongs in snac, DNSD, or Six-Man working groups
- **Multiple Infrastructure Routers**: Need to handle scenarios with multiple routers offering the service
- **Fallback Mechanisms**: Devices must fall back to MDNS if infrastructure service becomes unavailable
- **Enterprise Use Cases**: Potential application in enterprise environments with centralized DNS control

### Draft Issues Review

- **Prefix Delegation**: Extensive discussion on handling multiple prefix options (ULA vs GUA)
  - Recommendation to prefer GUA for better functionality
  - Consider using prefix lifetime as selection criteria
  - Account for constrained networks like Thread that may prefer single prefix
- **Guest Network Clarification**: Need to clarify communication limitations in guest network scenarios
- **IPv4 Support**: Discussion on removing IPv4 references as it's out of scope and not broadly supported
- **Editorial Improvements**: Multiple pull requests for constants, terminology consistency, and diagram additions

## Decisions and Action Items

### Decisions Made
- **Interim Meetings**: Schedule weekly meetings in September (specific dates to be determined via mailing list poll)
- **Pull Request Approval**: Approved one pull request correcting IPv4 router limitations text
- **Prefix Selection**: Consensus to recommend GUA over ULA when multiple prefixes available, with caveats for constrained networks

### Action Items
- **Ted**: Review and update multiple pull requests based on meeting feedback
- **Ted**: Create issue for adding reference links to all constants for better document navigation
- **Ted**: Update NAT64 state machine documentation to include proper RA state machine integration
- **Working Group**: Participate in mailing list discussions to review pending pull requests before first interim
- **Chairs**: Send out poll for specific September interim meeting dates
- **Matthew**: Submit individual draft (draft-00) documenting the Full DNSD Service Infrastructure proposal

## Next Steps

- **Mailing List Review**: Multiple pull requests require detailed review on the mailing list before next meeting
- **September Interims**: Weekly interim meetings scheduled for September to address remaining issues
- **Document Progress**: Goal to resolve all pending pull requests before first interim to focus on new work
- **Working Group Coordination**: Determine appropriate working group home for the Full DNSD Service Infrastructure work (potentially DNSD rather than snac)

The meeting demonstrated good progress on technical issues while identifying the need for more focused interim sessions to complete the specification work.