Also, I think, this has to do with following the offer-answer model. That is for each offer, there can be only one answer. If reliable provisional response is enabled, then answer sdp in 18x completes the model and so it is okay to exclude answer sdp from 200 OK. If a UAS decides to include answer sdp in 200 OK, it be a copy of the sdp sent in previous reliable response. If reliable provisional response is not enabled, then sdp in 200 OK is the answer sdp.
Sanjay >-----Original Message----- >From: Christer Holmberg (JO/LMF) >[mailto:[EMAIL PROTECTED] >Sent: Monday, February 19, 2007 2:29 PM >To: Attila Sipos; Sweeney, Andrew (Andrew); Ira Kadin; Sanjay >Sinha (sanjsinh); Miljanovic, Nebojsa (Neb); >[email protected] >Subject: RE: [Sip-implementors] SDP in 2xx response after reliable 18x > > >Hi, > >>>>Now, I don't know why the 2xx response's SDP should be ignored. >>>>Maybe someone can think of a scenario where not ignoring >the 2xx SDP >>>>would cause an error. ?? >>> >>>If you have already received SDP on the same dialog as the 200 SDP, >>>and you are listening to the media associated to that dialog, >it >>>should not cause an error - assuming the sender of the SDP behaves >correctly. >> >>You are talking about the standards again, are you not? >> >>What I mean is that clearly the SIP protocol has been designed this >>way because of some kind of problem that would >>be caused if it wasn't done this way. So, what are the problems? >What is an >>example that illustrates the problems? > >When SIP was "designed" there was no such thing as reliable >provisional responses etc. So, the only way to send the SDP >answer reliable was by using the 200 OK. The SDP sent in the >unreliable 18x is only a "preview". > >Regards, > >Christer > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
