Shepherd writeup

1. Summary

Document shepherd: Simon Perreault <>
Responsible Area Director: Spencer Dawkins <>

The intent of this document is to define a procedure for TURN clients to
discover servers available to them. In a nutshell the procedure tries, in order,
local configuration, S-NAPTR lookup of the client's domain name (obtained
from either DHCP or the application-layer identity), DNS-SD, and then a
well-known anycast address as last resort.

The requested publication type is Proposed Standard because it defines new
behaviour for TURN clients of which WebRTC is an immediate customer.

2. Review and Consensus

The document was heavily discussed and reviewed, both in TRAM and externally in
RTCWEB, by many participants. Much of the discussion revolved around security
considerations. The resulting text represents consensus of all participants.

Initial requirements for this work included discovery of network-provided
servers in both enterprise and ISP settings. DHCP and DNS-SD are targeted at the
enterprise setting while anycast is targeted at the ISP setting. DNS-SD was
suggested by a browser maker as an alternative mechanism that is typically more
easily usable than DHCP from a user-space application such as a web browser.

It is expected that WebRTC browsers will implement this specification. However,
although RETURN and TURN-bis contain informative references pointing to this
spec, it is not mandatory-to-implement for WebRTC.

3. Intellectual Property

Each author has stated that their direct, personal knowledge of any IPR related
to this document has already been disclosed, in conformance with BCPs 78 and 79.
There was no IPR disclosure.

4. Other Points

This document registers new well-known anycast IP address ranges, and that
requires IETF Review.