Re: [MMUSIC] When a bundle offer is forked

Martin Thomson <martin.thomson@gmail.com> Thu, 23 May 2013 21:57 UTC

Return-Path: <martin.thomson@gmail.com>
X-Original-To: mmusic@ietfa.amsl.com
Delivered-To: mmusic@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 4ACD321F8CB4 for <mmusic@ietfa.amsl.com>; Thu, 23 May 2013 14:57:52 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.508
X-Spam-Level:
X-Spam-Status: No, score=-4.508 tagged_above=-999 required=5 tests=[AWL=-0.909, BAYES_00=-2.599, RCVD_IN_DNSWL_LOW=-1]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lGUVtmzVnaVI for <mmusic@ietfa.amsl.com>; Thu, 23 May 2013 14:57:37 -0700 (PDT)
Received: from mail-lb0-f176.google.com (mail-lb0-f176.google.com [209.85.217.176]) by ietfa.amsl.com (Postfix) with ESMTP id DFB0221F8E2C for <mmusic@ietf.org>; Thu, 23 May 2013 14:09:54 -0700 (PDT)
Received: by mail-lb0-f176.google.com with SMTP id x10so3961219lbi.35 for <mmusic@ietf.org>; Thu, 23 May 2013 14:09:53 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=mieWA8ZLYnrTINhPcq6QTJuVRhJfDh8gI0YZaXp6WFU=; b=JAbN/jypsZ8ZV+OIPosW6c0o36f2iaduIMdBqrZa8gdDXxzsx4TZ4cewxvVCiDIbrc 1Ew9V9n+7807zZ5W2bfkQYA7m/wKgK9GAkGrWDZZmXyx1U3MoLZyfs/pdGVkHEEPCdXV /PWbEK2tQmcKIHo0RP9Y47k9l30h8vJV1IfaYa6Jb04q4s7bsFvYZzdvr2aLCDM4ZdBQ It6OQHaQNmM46vJbRR1gI/S65s57o1yAN5KNZe0yduh7tjTKmCSOCw57XTzWextIKeHr A8mEl+11rqbNmL/WsTrvqxif45xvzPBnQkOAYl2ZXIuKwRkwkfFJOfKAq1MHimrxkkWz n35Q==
MIME-Version: 1.0
X-Received: by 10.112.190.73 with SMTP id go9mr7435948lbc.43.1369343393847; Thu, 23 May 2013 14:09:53 -0700 (PDT)
Received: by 10.112.235.233 with HTTP; Thu, 23 May 2013 14:09:53 -0700 (PDT)
In-Reply-To: <519E530C.60705@alum.mit.edu>
References: <7594FB04B1934943A5C02806D1A2204B1C374357@ESESSMB209.ericsson.se> <519A1336.9010001@jitsi.org> <9F33F40F6F2CD847824537F3C4E37DDF1159D127@MCHP04MSX.global-ad.net> <519A229D.7090204@jitsi.org> <7594FB04B1934943A5C02806D1A2204B1C374463@ESESSMB209.ericsson.se> <519A2768.5010904@alum.mit.edu> <CAPvvaa+A=LkYp9A+wENAABwCYaQcD0HVeX4o+O_16iJRPXZfNw@mail.gmail.com> <7594FB04B1934943A5C02806D1A2204B1C3744DC@ESESSMB209.ericsson.se> <CAPvvaaJsPNk1DAJXYoc8aUgZ0ZayV_8q84W=Mm7vwuRRGuwC-g@mail.gmail.com> <7594FB04B1934943A5C02806D1A2204B1C374572@ESESSMB209.ericsson.se> <519A3883.8060006@jitsi.org> <519A3C8F.3040309@alum.mit.edu> <519B343A.30704@jitsi.org> <519BB598.1030909@alum.mit.edu> <519DF0F8.1070407@jitsi.org> <519E530C.60705@alum.mit.edu>
Date: Thu, 23 May 2013 14:09:53 -0700
Message-ID: <CABkgnnVhci+5FFDFYKHLASOMdqKWnGE2FgSqgjhjW+ES=fJTBg@mail.gmail.com>
From: Martin Thomson <martin.thomson@gmail.com>
To: Paul Kyzivat <pkyzivat@alum.mit.edu>
Content-Type: text/plain; charset="UTF-8"
Cc: mmusic <mmusic@ietf.org>, Christer Holmberg <christer.holmberg@ericsson.com>
Subject: Re: [MMUSIC] When a bundle offer is forked
X-BeenThere: mmusic@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Multiparty Multimedia Session Control Working Group <mmusic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/mmusic>, <mailto:mmusic-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/mmusic>
List-Post: <mailto:mmusic@ietf.org>
List-Help: <mailto:mmusic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/mmusic>, <mailto:mmusic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 23 May 2013 21:57:52 -0000

The more I think about forking, the more I don't want to think about
it any more.

On 23 May 2013 10:34, Paul Kyzivat <pkyzivat@alum.mit.edu> wrote:
> * if the bundle is accepted by multiple forks, does this form
>   one RTP session or several?

If the subjective view of the RTP session that the offerer holds is
bound to a 5-tuple (as opposed to just local addressing), then this
forms multiple sessions.

However...

Prior to getting answer(s), the offerer might be unable to tell that
there are multiple RTP sessions, or if it is just media arriving from
multiple source addresses.  This would only be a problem in the
absence of ICE and with multiple m-lines.

> * How does ICE work in this case? (Is that already covered by ICE,
>   since it mostly isn't specific to bundle?

I believe that ICE works in this case.  Each RTP session should have a
different set of ufrag/pwd for the peer.

I know that others have talked about the implications for the ICE
state machine for bundle, but that depends on ufrag/pwd.

> * If one fork adds/removes an m-line from the bundle, should that
>   be mirrored to the other forks?

I don't see how that has a significant impact.  Each fork could choose
different bundling configurations.  This is not significantly
different to other forking cases.  The offerer has to be prepared to
demux at the session layer first.