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Re: [webrtc-pc] Ambiguities with BUNDLE and ICE

From: Taylor Brandstetter via GitHub <sysbot+gh@w3.org>
Date: Fri, 27 Apr 2018 18:14:44 +0000
To: public-webrtc-logs@w3.org
Message-ID: <issue_comment.created-385051864-1524852883-sysbot+gh@w3.org>
I think [this PR](https://github.com/cdh4u/draft-sdp-bundle/pull/59) will clear up the ambiguities, putting things in terms of m= sections rather than addresses. Similar to [what I tried to do earlier](https://github.com/cdh4u/draft-sdp-bundle/pull/19). A relevant excerpt:

> When an answerer generates the answer, if the answerer wants to move a bundled "m=" section out of the negotiated BUNDLE group, the answerer MUST first check the following criteria:
> 
> - In the corresponding offer, the "m=" section is within a previously negotiated BUNDLE group; and
> - In the corresponding offer, the "m=" section contains an SDP 'bundle-only' attribute.
> 
> If either criterium above is fulfilled the answerer can not move the "m=" section out of  the BUNDLE group in the answer. The answerer can either reject the whole offer, reject each bundled "m=" section within the BUNDLE group, or keep the "m=" section within the BUNDLE group in the answer and later 
> create an offer where the "m=" section is moved out of the BUNDLE group.
> 
> NOTE: One consequence of the rules above is that, once a BUNDLE group has been negotiated, a bundled "m=" section can not be moved out of the BUNDLE group in an answer. Instead an offer is needed.

So, once something is bundled, only an offer can remove it. There's no way to allow the answer to choose whether to keep something bundled, like there previously was.

Also:

> When an answerer wants to reject a bundled "m=" section in an answer, it MUST first check the following criterium:
> 
> - In the corresponding offer, the "m=" section is the offerer tagged "m=" section.
> 
> If the criterium above is fulfilled the answerer can not reject the "m=" section in the answer. The answerer can either reject the whole offer, reject each bundled "m=" section within the BUNDLE group, or keep the "m=" section within the BUNDLE group in the answer and later create an offer where the "m=" section is disabled within the BUNDLE group.

So, there's no way to do what's described in the original example above. The answerer can choose to reject the "video" section, or reject all of them, but it can't reject just the "audio" section, and it can't remove either from the BUNDLE group without rejecting.

-- 
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Please view or discuss this issue at https://github.com/w3c/webrtc-pc/issues/1563#issuecomment-385051864 using your GitHub account
Received on Friday, 27 April 2018 18:14:47 UTC

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