Re: [MMUSIC] draft-ejzak-mmusic-data-channel-sdpneg: external rejection of channel

On Wed, Feb 26, 2014 at 7:30 AM, Christer Holmberg <
christer.holmberg@ericsson.com> wrote:

>  Hi,
>
>
>
> Section 5.2.2 describes what an answerer does when accepting a data
> channel:
>
>
>
>   "The peer receiving such an SDP offer performs the following:
>
>
>
>                 ...
>
>
>
>    o  For accepted data channels, creates peer instances for the data
>
>       channels with the browser using the channel parameters described
>
>       in the SDP offer.  Note that the browser is asked to create data
>
>       channels with stream identifiers not "owned" by the agent."
>
>
>
> But, there is no text on rejecting a data channel in the SDP answer.
>
>
>
> The answer can of course reject the whole m- line, using port zero in the
> Answer m- line. But, how does the answerer reject an individual
> sub-protocol data channel?
>

Only attributes for "accepted data channels" are included in the SDP
answer, which indicates back to the offerer which ones are rejected (they
just aren't there).  This should be made clearer in the text.

>
>
> Section 5.1.1 says, regarding the SDP dcmap attribute, for accepted data
> channels:
>
>
>
> "This line MUST be replicated without changes in the SDP answer, if
>
>                 the answerer accepts the offered data channel."
>
>
>
> I guess one way to reject would be to simply not include the dcmap
> attribute in the Answer, and the Offerer then needs to figure out what was
> rejected based on the stream values not present in the Answer.
>

Yes.  That is what was intended.

BR, RIchard

>
>
> Regards,
>
>
>
> Christer
>
>
>
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