Subject: [rtcweb] Revision of bundling proposal/analysis

From: [email-masked] (Dale R. Worley)
Date: Mon, 11 Mar 2013 12:00:20 -0400 (EDT)

I've just submitted draft-worley-sdp-bundle-05, which is an SDP
bundling proposal along with a bunch of analysis and comparison to
other bundling proposals.

The biggest change is adding a detailed analysis of alternatives for
the address/port combinations to be used when offering constituent
media descriptions (m= lines) so as to get all the mechanics to work
as we'd like.  It is from this analysis I noticed that we don't have a
good method to *answer* a constituent media description.  (I've sent
e-mail about that to MMUSIC.)

I've added an example containing two SCTP media descriptions, which
will be a common case on WebRTC.

A change that I have not yet made is removing the RTP encapsulation
payload format ("kumquat" itself).  It looks like encapsulation works
against some properties we'd like the solution to have.
Unfortunately, removing encapsulation causes constraints in other
parts of the solution.  In particular, different media descriptions
will be constrained to have different payload type numbers, and
bundling can't support multiple transport addresses or multiple ports
within a single media description.

Dale

A new version of I-D, draft-worley-sdp-bundle-05.txt
has been successfully submitted by Dale R. Worley and posted to the
IETF repository.

Filename:	 draft-worley-sdp-bundle
Revision:	 05
Title:		 Kumquat: A Generic Bundle Mechanism for the Session Description Protocol (SDP)
Creation date:	 2013-03-11
Group:		 Individual Submission
Number of pages: 42
URL:             http://www.ietf.org/internet-drafts/draft-worley-sdp-bundle-05.txt
Status:          http://datatracker.ietf.org/doc/draft-worley-sdp-bundle
Htmlized:        http://tools.ietf.org/html/draft-worley-sdp-bundle-05
Diff:            http://www.ietf.org/rfcdiff?url2=draft-worley-sdp-bundle-05

Abstract:
   This document defines a generic bundle mechanism for the Session
   Description Protocol (SDP) by which the media described by a number
   of media descriptions ("m= lines") are multiplexed and transmitted
   over a single transport association.  The transport association is
   described by an additional media description, allowing SDP attributes
   to be applied to the aggregate, independently of attributes applied
   to the constituents.  In offer/answer usage, the bundle mechanism is
   backward compatible with SDP processors that do not understand the
   mechanism.  The mechanism is designed to be compatible with the
   limitations of the existing Internet infrastructure.

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From: Randell Jesup <[email-masked]>
Date: Sun, 24 Mar 2013 01:17:30 -0400

> will be a common case on WebRTC.

Actually, we nominally support only a single DataChannel connection per 
PeerConnection (at the W3 level), so you'll never have the example given 
in WebRTC.

Using BUNDLE outside of WebRTC would change that.

I also was surprised at encapsulating SRTP packets *inside* DTLS (and 
DTLS packets *inside* DTLS).

-- 
Randell Jesup
[email-masked]

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From: [email-masked] (Dale R. Worley)
Date: Mon, 25 Mar 2013 17:38:40 -0400 (EDT)

> From: Randell Jesup <[email-masked]>
> 

Where does that come from?

Dale