Re: [MMUSIC] BUNDLE: Accept m- line, reject bundle

Paul Kyzivat <pkyzivat@alum.mit.edu> Fri, 03 May 2013 15:43 UTC

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Date: Fri, 03 May 2013 11:01:21 -0400
From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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Subject: Re: [MMUSIC] BUNDLE: Accept m- line, reject bundle
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On 5/3/13 9:07 AM, Christer Holmberg wrote:
> Hi,
>
> Assume the following case:
>
> 1.An SDP offer contains an m- line associated with a BUNDLE group
>
> 2.The answerer wants to accept the m- line, but wants to reject it being
> in the specific BUNDLE group.
>
> A few alternatives on how this could be achieved have been presented:
>
> Alt 1.      The answerer accepts the m- line, but does not associate it
> with a BUNDLE group.
>
> Alt 2.      The answerer accepts the m- line, associates it with a
> BUNDLE group, and then sends a new offer which removes the m- line from
> the BUNDLE group.
>
> Alt 3.      The answerer rejects the m- line, and then sends a new offer
> which adds the m- line outside a BUNDLE group.
>
> In my opinion, Alt 1 does not work, at least not if the offer contains
> identical port values for the m- lines associated with the BUNDLE group.
> It would mean that the m- line is not added to a BUNDLE group, but still
> has the same port value (at least at the offerer side) as the m- lines
> in the BUNDLE group, which is not allowed.
>
> So, my suggestion would be to specify that the answerer must use Alt 2
> and/or Alt 3.

I don't think we should restrict flexibility here when it works and 
makes sense.

I agree that Alt 1 doesn't work *if* the m-line in question shares 
addr/prot with other m-lines that are also accepted, bundled or not. But 
the normal first offer won't present that situation. If the addr/port in 
the m-line in question is unique among all the accepted m-lines, then 
this should be acceptable.

(Note, this is a degenerate case of bundle splitting. There are real use 
cases for it. If it can be done without a 2nd o/a, then lets allow that.)

	Thanks,
	Paul