The Alternative Network Address Types (ANAT) Semantics for the Session Description Protocol (SDP) Grouping Framework
RFC 4091

Approval announcement
Draft of message to be sent after approval:

From: The IESG <iesg-secretary@ietf.org>
To: IETF-Announce <ietf-announce@ietf.org>
Cc: Internet Architecture Board <iab@iab.org>,
    RFC Editor <rfc-editor@rfc-editor.org>, 
    mmusic mailing list <mmusic@ietf.org>, 
    mmusic chair <mmusic-chairs@tools.ietf.org>
Subject: Protocol Action: 'The Alternative Network Address Types 
         Semantics (ANAT) for theSession Description Protocol (SDP) 
         Grouping Framework' to Proposed Standard 

The IESG has approved the following document:

- 'The Alternative Network Address Types Semantics (ANAT) for theSession 
   Description Protocol (SDP) Grouping Framework '
   <draft-ietf-mmusic-anat-03.txt> as a Proposed Standard

This document is the product of the Multiparty Multimedia Session Control 
Working Group. 

The IESG contact persons are Jon Peterson and Cullen Jennings.

A URL of this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-mmusic-anat-03.txt

Technical Summary
 
This addition to the Session Description Protocol (SDP) allows an SDP offer to 
contain more than one network address associated with a single offered media 
stream. The motivation for this is IPv6 transition - it allows a dual-stack 
client to offer both an IPv6 and an IPv4 address from which the answerer can 
choose. It also allows these addresses to be prioritized, so an offerer can 
indicate that they would prefer to connect via IPv6, if possible. This has 
significant applicability to the Interactive Connectivity Establishment (ICE) 
mechanism being developed in MMUSIC.
 
Working Group Summary
 
The MMUSIC working group supported the advancement of this document. A concern 
was expressed that interaction of other media grouping semantics in SDP was 
insufficiently specified, but the media grouping framework was authored by some
f the same individuals who wrote this document, and they seem to feel that the 
distinction is clear enough.
 
Protocol Quality
 
This specification was reviewed for the IESG by Jon Peterson.