Re: [MMUSIC] Bundle offer with different ports - where to expect media?

Paul Kyzivat <pkyzivat@alum.mit.edu> Thu, 23 May 2013 22:26 UTC

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Date: Thu, 23 May 2013 17:39:50 -0400
From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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To: Martin Thomson <martin.thomson@gmail.com>
References: <7594FB04B1934943A5C02806D1A2204B1C374357@ESESSMB209.ericsson.se> <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> <CAOJ7v-398_MiXLWjexU0Z0xQju3A-zWuQFkWkJSLPA5UEGAu+g@mail.gmail.com> <CABkgnnXqBzteoxH2qWBw1Xn9PHt2r___UCsp1Eoq4o8_VWvBZg@mail.gmail.com> <CAOJ7v-2xXb=uz3jBAKSXhyJ2mU9BGvYHZ=dkeKcZTWov7udWKQ@mail.gmail.com> <519CCE58.3000807@alum.mit.edu> <CAMvTgcdPZfBTyzoBZGCdJiHX+TaL3_T8+MnxH8+6vQPFTD4ZOA@mail.gmail.com> <CAOJ7v-1tmfy4Fu05ChcpbZT=bO-zr05qtOh9Lnw5bprbUEnoDw@mail.gmail.com> <C5E08FE080ACFD4DAE31E4BDBF944EB11350E214@xmb-aln-x02.cisco.com> <CABkgnnXgvEWtAs_yYu3ZZw0_TuFtgs_aOhpTrVaYZsfGd+hk+g@mail.gmail.com>
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Cc: "Cullen Jennings \(fluffy\)" <fluffy@cisco.com>, Christer Holmberg <christer.holmberg@ericsson.com>, mmusic <mmusic@ietf.org>
Subject: Re: [MMUSIC] Bundle offer with different ports - where to expect media?
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On 5/23/13 4:55 PM, Martin Thomson wrote:
> On 23 May 2013 06:41, Cullen Jennings (fluffy) <fluffy@cisco.com> wrote:
>> On May 22, 2013, at 4:55 PM, Justin Uberti <juberti@google.com> wrote:
>>
>>> I think we could do this using the existing syntax, e.g.
>>>
>>> an offer of a=group:BUNDLE A B C would indicate that the offerer would prefer A, B, and C to be muxed onto A, and
>>> an answer of a=group:BUNDLE C A would indicate that the answerer is going to mux C and A onto C, and send B unbundled.
>>>
>>
>> I suspect several people are on the fence about using this approach or the first non rejected m-line in the bundle.
>>
>> Can anyone think of reasons why to pick one of the other of these two approaches ?
>
> I was originally strongly in favor of basing transport parameter
> choice solely on the order of m-lines in the SDP document.
>
> However, after our discussion this morning, if we allow a previously
> rejected m-line to be revived and added to a BUNDLE group, then the
> rule stating that any existing transport is used would take precedence
> over this.
>
> But that sucks.  I have a better solution for this case. We should
> require that previously negotiated m-lines cannot change their BUNDLE
> affiliation.  That would prevent the old m-line from being re-added to
> an existing BUNGLE.  A new m-line would be required.

I am pretty strongly opposed to restricting how one can recycle m-lines.
IMO this is a pretty basic and fundamental mechanism.

Your concern is only important if you we use the "first m-line in the 
SDP that is non-zero and part of the bundle" rather than "first mid in 
the bundle that identifies a non-zero m-line". I thought we settled that.

	Thanks,
	Paul