IETF Logo Mail Archive

Re: [rtcweb] How to multiplex between peers

Matthew Kaufman <matthew.kaufman@skype.net> Wed, 20 July 2011 19:51 UTC

Return-Path: <matthew.kaufman@skype.net>
X-Original-To: rtcweb@ietfa.amsl.com
Delivered-To: rtcweb@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id E44D121F86D7 for <rtcweb@ietfa.amsl.com>; Wed, 20 Jul 2011 12:51:21 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.577
X-Spam-Level:
X-Spam-Status: No, score=-2.577 tagged_above=-999 required=5 tests=[AWL=0.022, BAYES_00=-2.599]
Received: from mail.ietf.org ([64.170.98.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HBID1w8uSwpS for <rtcweb@ietfa.amsl.com>; Wed, 20 Jul 2011 12:51:18 -0700 (PDT)
Received: from mx.skype.net (mx.skype.net [78.141.177.88]) by ietfa.amsl.com (Postfix) with ESMTP id CCBF921F86D6 for <rtcweb@ietf.org>; Wed, 20 Jul 2011 12:51:17 -0700 (PDT)
Received: from mx.skype.net (localhost [127.0.0.1]) by mx.skype.net (Postfix) with ESMTP id 966CD1708; Wed, 20 Jul 2011 21:51:16 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=skype.net; h=subject :mime-version:content-type:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; s=mx; bh=iK 49D8pS+ll8uzgGf2qJcFSq67Y=; b=ZvVOkNoT2H6kcmfCrWc5gZ2hR8GRkpDaln 1TdSO9R4lc/jUa0f9OugEaLdsJIc1LP6zhl4sfbm3ZmBtFompihcbH1Vz73VYmR5 akfhdUzuGZsTJ+BJgKe7O/cIs9yW+Z06ZaTmhepovyPigH4gmfFXvXhM0RG89wMA 4ixeD9rF0=
DomainKey-Signature: a=rsa-sha1; c=nofws; d=skype.net; h=subject:mime-version :content-type:from:in-reply-to:date:cc:content-transfer-encoding :message-id:references:to; q=dns; s=mx; b=N47oXiQFqGcQcRu3QtXnQn cOHs7fIRcwA3XVSDgszXWExhlnzpjagTwQ07GpxZVYlm3yssh/dZo4hVhz7ELCvl a8IbUcRknEcriHYmYN7bGKBMgYeVjsInQZyresi4lDmc7zqLQYA02OGfpgvjHAQB nJtIy10mYCixin9u7fjDA=
Received: from zimbra.skype.net (zimbra.skype.net [78.141.177.82]) by mx.skype.net (Postfix) with ESMTP id 94C597FC; Wed, 20 Jul 2011 21:51:16 +0200 (CEST)
Received: from localhost (localhost [127.0.0.1]) by zimbra.skype.net (Postfix) with ESMTP id 6DD1135080C2; Wed, 20 Jul 2011 21:51:16 +0200 (CEST)
X-Virus-Scanned: amavisd-new at lu2-zimbra.skype.net
Received: from zimbra.skype.net ([127.0.0.1]) by localhost (zimbra.skype.net [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id jPdQLJ+PGkIE; Wed, 20 Jul 2011 21:51:15 +0200 (CEST)
Received: from [172.17.61.96] (50-0-2-20.static.sonic.net [50.0.2.20]) by zimbra.skype.net (Postfix) with ESMTPSA id 2BD6C3507E96; Wed, 20 Jul 2011 21:51:15 +0200 (CEST)
Mime-Version: 1.0 (Apple Message framework v1082)
Content-Type: text/plain; charset="us-ascii"
From: Matthew Kaufman <matthew.kaufman@skype.net>
In-Reply-To: <CAOJ7v-2kwiCipJSHmNT9GuGJJzEjPV-X00TLnf-LwbsJ1ADwDw@mail.gmail.com>
Date: Wed, 20 Jul 2011 12:51:12 -0700
Content-Transfer-Encoding: quoted-printable
Message-Id: <896BDC4C-849C-4553-89C8-7EFEF9FFEC6B@skype.net>
References: <4E259EAD.3060505@ericsson.com> <FAE78F7C-8C51-41C4-B3D7-6497396E12A5@cisco.com> <4E26C5CF.1080007@ericsson.com> <BLU152-W54BE1A03753680FF0094C4934C0@phx.gbl> <CAOJ7v-2kwiCipJSHmNT9GuGJJzEjPV-X00TLnf-LwbsJ1ADwDw@mail.gmail.com>
To: Justin Uberti <juberti@google.com>
X-Mailer: Apple Mail (2.1082)
Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] How to multiplex between peers
X-BeenThere: rtcweb@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <rtcweb.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/rtcweb>
List-Post: <mailto:rtcweb@ietf.org>
List-Help: <mailto:rtcweb-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 20 Jul 2011 19:51:22 -0000

On Jul 20, 2011, at 12:46 PM, Justin Uberti wrote:

> 
> This is where I've ended up on this topic. We can easily multiplex multiple RTP sources (of the same type) over a single RTP session using SSRC. We can also mux RTCP over the RTP session using RTCP mux. So, for an arbitrary video call, we have just 2 RTP sessions/NAT bindings. 
> 
> Is it worth going the extra mile to get down to 1 in v1.0, given the lack of consensus that exists right now? Is there even a compelling argument to do so?

Yes and yes.

I really can't understand why, if we can multiplex 3 totally different types of video streams over the same RTP session using SSRC (with wildly different bit-rates, inter-packet times, etc.) we can't also multiplex audio and video. Not a single argument that has been presented has convinced me, and getting from 2 to 1 is a *50%* reduction in NAT port utilization. (And a significant reduction in the number of "strange" failure modes, where one traversal worked and the other didn't.)

Matthew Kaufman

v2.23.0 | Report a Bug | By Email