Re: [MMUSIC] BUNDLE DECISSION: SDP Answer Restrictions

Christer Holmberg <> Mon, 27 May 2013 10:53 UTC

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From: Christer Holmberg <>
To: Paul Kyzivat <>, "" <>
Thread-Topic: [MMUSIC] BUNDLE DECISSION: SDP Answer Restrictions
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Date: Mon, 27 May 2013 10:53:43 +0000
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Subject: Re: [MMUSIC] BUNDLE DECISSION: SDP Answer Restrictions
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>> At the interim meeting yesterday, we agreed on some restrictions 
>> regarding creating SDP answers containing bundle group(s).
>> Note that the restrictions 1-3 are simply alignments with RFC 5888, 
>> and are listed simply for clarification purpose. Restrictions 4 is 
>> BUNDLE specific. Restriction 5 is also alignment with RFC 5888, as m- 
>> lines with port zero are not allowed within groups, but we will need 
>> some clarification text saying that a new offer will have to be sent 
>> in order to remove a stream (either from a bundle group, or completely 
>> from the session).
>> (Note that the text below is not necessarily the wording that will go 
>> into the draft)
>> In an SDP answer:
>> 1)a BUNDLE group MUST NOT be created, unless it was included in the 
>> associated offer
>> 2)an m- line MUST NOT be added to a BUNDLE group, unless it was 
>> included in a BUNDLE group in the associated offer
>> 3)an m- line MUST NOT be added to another BUNDLE group than the group 
>> in which was included in the associated offer
>> 4)an m- line MUST NOT be removed from a BUNDLE group if, in the 
>> associated offer, an identical port number was indicated for all m- 
>> lines in a BUNDLE group
>> 5)an m- line MUST NOT be rejected if, in the associated offer, an 
>> identical port number was indicated for all m- lines in a BUNDLE group
> Where did (5) come from? And what is the justification for it?
> I can see no good reason to impose this restriction.

I was checking my notes, but could not find anything justifying it. Maybe I mixed it up with the offer restrictions we were discussing...

> Note that there is also a discussion regarding bundle offers, e.g. 
> when restrictions when adding new m- lines to a bundle. Based on the 
> outcome of that, there may be some additional answer restrictions, e.g.
> regarding the change of bundle transport parameters. But, let's deal 
> with that in the offer thread.