[SR-Users] RTPengine: shouldn't SDP <sess-version> be incremented when SDP is updated in-dialog?

[George Diamantopoulos]

We've run into an issue again, where a provider won't accept re-INVITEs for
session refresh where the SDP version counter hasn't been incremented. Has
there been any work on this or should I open an issue at github to make
this issue more visible?

Thanks!
George

On Fri, 4 May 2018 at 17:51, Richard Fuchs <rfuchs at sipwise.com> wrote:

> On 04/11/2018 09:28 AM, George Diamantopoulos wrote:
> > Hello all,
> >
> > I have the following issue (I think) with RTP engine. An INVITE comes
> > in, and rtpengine will rewrite the SDP accordingly, as configured in
> > kamailio.cfg. After some time a reINVITE is sent out in the opposite
> > direction, for session refresh purposes. As I use rtcp-mux-offer in
> > kamailio.cfg for this direction, RTPengine will inject the rtcp-mux
> > parameter, and this reINVITE is forwarded to the UAC that sent the
> > original INVITE.
> >
> > However, the SDP in the reINVITE is exactly the same as the SDP in the
> > 200 OK to the original INVITE, with the exception of the rtcp-mux
> > parameter. Since the SDP offered from the same end has changed,
> > shouldn't session version be incremented as well?
> >
> > Does this sound like something that should be reported as a bug to
> > rtpengine? Or am I missing something here?
>
> Technically of course you're correct in that the version counter should
> be incremented if the SDP changed. Currently rtpengine always leaves the
> o= line unchanged, so there can be a discrepancy here in certain cases.
> This should probably be fixed, but this is also the first time I've
> heard of this actually causing an issue.
>
> Cheers
>
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