Re: [MMUSIC] Associating packets with m-lines in a bundle

worley@ariadne.com (Dale R. Worley) Thu, 23 May 2013 22:35 UTC

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Date: Thu, 23 May 2013 18:07:29 -0400 (EDT)
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From: worley@ariadne.com (Dale R. Worley)
Sender: worley@ariadne.com (Dale R. Worley)
To: Paul Kyzivat <pkyzivat@alum.mit.edu>
In-reply-to: <519E5F54.3000806@alum.mit.edu> (pkyzivat@alum.mit.edu)
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Cc: mmusic@ietf.org
Subject: Re: [MMUSIC] Associating packets with m-lines in a bundle
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> From: Paul Kyzivat <pkyzivat@alum.mit.edu>
> 
> IMO the following should obviously be a truism. I want to know if all agree.
> 
> If an O/A exchange negotiates a bundle with multiple m-lines,
> then attributes in those m-lines and the associated media sections must 
> provide sufficient information to associate each incoming packet on the 
> 5-tuple to exactly *one* of those m-lines.

I agree.  I think there are non-legacy situations where this need may
be relaxed, but all interoperation in legacy situations seems to
require discerning the appropriate m= line so information in the SDP
section can be used to identify the particular application processing
stream.

> [...] receiving packets that don't match any of the m-lines. I 
> think we ought to address that, by defining some syntax to specify what 
> to do with packets that don't match any m-line. This might be to specify 
> one m-line as the default, or that packets that don't match be discarded.

I think that discarding them is the only workable approach.  There's
no reason to assume that sending them to a default m= line would allow
the upper level of demultiplexing to succeed.

Dale