Discovery Proxy for Multicast DNS-Based Service Discovery

Approval announcement
Draft of message to be sent after approval:

From: The IESG <>
To: IETF-Announce <>
Cc: The IESG <>,,,, Tim Chown <>,,,
Subject: Protocol Action: 'Discovery Proxy for Multicast DNS-Based Service Discovery' to Proposed Standard (draft-ietf-dnssd-hybrid-08.txt)

The IESG has approved the following document:
- 'Discovery Proxy for Multicast DNS-Based Service Discovery'
  (draft-ietf-dnssd-hybrid-08.txt) as Proposed Standard

This document is the product of the Extensions for Scalable DNS Service
Discovery  Working Group.

The IESG contact persons are Suresh Krishnan and Terry Manderson.

A URL of this Internet Draft is:

Technical Summary

Classic mDNS and DNS-SD only operate across the scope of a single link. There is thus a challenge in service discovery for multi-link networks, from home networks through to large enterprises or campuses. This document specifies a type of proxy called a "Multicast Discovery Proxy" (or just "Discovery Proxy") that uses Multicast DNS to discover Multicast DNS records on its local link, and makes corresponding DNS records visible in the Unicast DNS namespace. Host queries are forwarded to proxies on remote links which perform multicast resolution of those queries, returning unicast answers.  Hosts may use LLQ or DNS Push for queries, to subscribe to DNS updates to obtain timely information. Other optimisations are described in other WG documents.

Working Group Summary

The draft moved fairly smoothly through various iterations. Until late in the process it was referred to the Hybrid Proxy, hence the draft file name, but it was then renamed the Discovery Proxy to allow the potential for a future Advertising Proxy to be defined with a clear, distinct purpose.

Document Quality

The appendix describes existing implementation status, which includes at least three (part) implementations.  There is interest amongst multiple vendors to take the work forward, beyond just Apple.  There has been a good number of reviews performed on the document over the past year or so, and there has been close cooperation with the DNSOP WG through Tim and Suzanne on the DNS Push and DNS Session Signal drafts that the Proxy can benefit from. 


Tim Chown is the document shepherd (and co-chair of the WG), and Terry Manderson is the Responsible AD.