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.