The Session Description Protocol (SDP) Label Attribute
RFC 4574

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 SDP (Session Description 
         Protocol) Label Attribute' to Proposed Standard 

The IESG has approved the following document:

- 'The SDP (Session Description Protocol) Label Attribute '
   <draft-ietf-mmusic-sdp-media-label-02.txt> as a Proposed Standard

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

The IESG contact persons are Allison Mankin and Jon Peterson.

A URL of this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-mmusic-sdp-media-label-02.txt

Technical Summary
 
   This specification defines a new Session Description Protocol (SDP)
   media-level attribute: "label".  The "label" attribute carries a
   pointer to a media stream in the context of an arbitrary network
   application that uses SDP.  The sender of the SDP document can attach
   the "label" attribute to a particular media stream or streams.  The
   application can then use the provided pointer to refer to each or all
   of the media in its particular context.

   SDP is a body or document used by other protocols.  It is left to the using
   applications to manage the "label" attribute.  However an important 
   user of the attribute is identified, the XCON framework.  The
   SIP conferencing package, in review at the same time as this
   specification,  is another important using protocol.

Working Group Summary
 
 The document carefully reviews why other SDP attributes or functionality which
 to provide this labeling function were not chosen.  The working group had
 raised each of the alternatives and discussed the points through to consensus.
 Before working group last call, there was a thorough document review by
 Magnus Westerlund, and the specification revised for small issues from that
 was supported for advancement.
 
Protocol Quality
 
 Allison Mankin has reviewed the specification for the IESG.

Note(s) to the RFC Editor
 
Replace normative reference to RFC 2234 with normative reference
to draft-crocker-abnf-rfc2234bis-00.txt
[DS in RFC Editor Queue]

Section 1. Add a sentence at the end of the second paragraph.

OLD:
[...]
media stream's role in the conference) about it.

NEW:
[...]
media stream's role in the conference) about it. The SIP Event
Package for Conference State [Informative refence to
draft-ietf-sipping-conference-package] defines and uses a concrete
format for such external documents.

Section 4:  extend the ABNF as follows:

OLD:

Its formatting in SDP is described by the following BNF
   [2]:


       label-attribute    = "a=label:" pointer
       pointer            = token

NEW:

Its formatting in SDP is described by the following ABNF
   [normative reference to  draft-crocker-abnf-rfc2234bis-00.txt]:


       label-attribute    = "a=label:" pointer
       pointer            = token
       token-char =          %x21 / %x23-27 / %x2A-2B / %x2D-2E / %x30-39
                            / %x41-5A / %x5E-7E

       token =               1*(token-char)


      The token-char and token elements are defined in [give a Normative
      reference to draft-ietf-mmusic-sdp-new-24.txt] but included here to
      provide support for the implementor of this SDP feature.


Section 6: addition of an 'i' line to the example:
OLD:
          v=0
          o=bob 280744730 28977631 IN IP4 host.example.com
          s=
          c=IN IP4 192.0.2.2
          t=0 0
          m=audio 6886 RTP/AVP 0
          a=label:1
          m=audio 22334 RTP/AVP 0
          a=label:2

NEW
          v=0
          o=bob 280744730 28977631 IN IP4 host.example.com
          s=
          i=A Seminar on the session description protocol
          c=IN IP4 192.0.2.2
          t=0 0
          m=audio 6886 RTP/AVP 0
          a=label:1
          m=audio 22334 RTP/AVP 0
          a=label:2

 Add to the beginning of Section 8 -

     Upon approval of this specification, IANA is requested to register
     the following new SDP attribute: