Re: [MMUSIC] BUNDLE DECISSION: SDP Answer Restrictions

Christer Holmberg <> Mon, 27 May 2013 14:28 UTC

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From: Christer Holmberg <>
To: "Cullen Jennings (fluffy)" <>
Thread-Topic: [MMUSIC] BUNDLE DECISSION: SDP Answer Restrictions
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Date: Mon, 27 May 2013 14:28:22 +0000
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Subject: Re: [MMUSIC] BUNDLE DECISSION: SDP Answer Restrictions
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> 4 and 5 are very confusing and do not match the notes I had from the call. I'm pretty sure I disagree with both of them.
> From a requirement point of view, I think it is very important that the answer be able to reject any m-line by setting it's port to zero.

Forget about 5 (at least for now) - I probably mixed some things up.

My take from the meeting is that there was an agreement on 4.

But, if you disagree with 4, which port do you think the offerer shall use for receiving media? It cannot use the "bundle port", as the answerer removed the m- line from the bundle group.



On May 24, 2013, at 6:32 AM, Christer Holmberg <> wrote:

> Hi,
> 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
> 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.
> So, if anyone OBJECTS to the restrictions above, please indicate so.
> Regards,
> Christer
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