Re: [MMUSIC] AD Review: draft-ietf-mmusic-t140-usage-data-channel

[Paul Kyzivat <[e-mail]>]

On 1/27/20 11:03 AM, Christer Holmberg wrote:
> Hi,
> 
> ....
>      
>      >> sdpneg has the following wording in 6.2 for the error case when both
>      >> parameters are included in the answer:
>      >>
>      >>    "If an SDP answer contains both
>      >>     of these parameters then the offerer MUST treat the associated SDP
>      >>     offer/answer as failed."
>      >
>      > The tricky part of treating the O/A as having failed is that only the
>      > offerer knows this, while the answerer thinks it has succeeded. So the
>      > two sides have differing understandings of the state of the session.
>      > (Consider that there may also have been changes in another media
>      > section.) Things will not go well until this is corrected.
>      >
>      > I don't know if there is any document that specifies what to do in this
>      > situation. I think there are only two generic possibilities: drop the
>      > entire session (i.e., BYE), or start another O/A to try to fix this,
>      > perhaps by dropping the m= line. When following this latter course,
>      > there will be an extended period while the two sides are in
>      > disagreement, and no guarantee that the fix will work.
>      >
>      > The simplest solution is to simply say that this is a protocol
>      > violation, and recovery is an implementation issue. While simple to
>      > write, this is perhaps not the best solution.
> 
> That is normally what we say.
> 
> However, if more text is needed I think it belongs to the data channel sdpneg draft. I don't think that each data channel usage draft shall have to describe how it is done.

Then I think the best path might be to update sdpneg with some specific 
language, and then update this draft to refer to that.

	Thanks,
	Paul