Hi, 180 can contain a SDP. However, not every message that contains an SDP is an answer to the initial offer. 180 are un-reliable messages (without 100 rel supported).
Anyways, there are far too many combinations to put here. In short, if you support 100 rel (which based on your callflow you do), the producer of sx2 is correct. For a detailed analysis, please give heed to Christer's advice. Thanks & Regards, Aditya Sehgal On Thu, May 22, 2008 at 2:32 PM, Christer Holmberg < [EMAIL PROTECTED]> wrote: > Hi, > > Please take a look at the draft-ietf-sipping-sip-offeranswer draft. > > Regards, > > Christer > > ------------------------------ > *From:* [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] *On Behalf Of *Yuantao > Zhang > *Sent:* 22. toukokuuta 2008 11:55 > *To:* [email protected] > *Subject:* [Sip] MUST 200 OK contain SDP? Thanks > > Dear all > > I am really confused by the following part in RFC_3261. Could you please > help us to explain it? Thank you very much. > > " > > 13.2.1 Creating the Initial INVITE > > . > > . > > . > > o If the initial offer is in an INVITE, the answer MUST be in a > > reliable non-failure message from UAS back to UAC which is > > correlated to that INVITE. For this specification, that is > > only the final 2xx response to that INVITE. That same exact > > answer MAY also be placed in any provisional responses sent > > prior to the answer. The UAC MUST treat the first session > > description it receives as the answer, and MUST ignore any > > session descriptions in subsequent responses to the initial > > INVITE. > > . > > . > > ." > > Let's break it into 2 parts, in part 1, > > "If the initial offer is in an INVITE, the answer MUST be in a > > reliable non-failure message from UAS back to UAC which is > > correlated to that INVITE. For this specification, that is > > only the final 2xx response to that INVITE. " > > Does that mean if "Invite" contains SDP offer, "200 OK" MUST contain SDP > answer. > > In part 2, > > "That same exact answer MAY also be placed in any provisional > responses sent > > prior to the answer. The UAC MUST treat the first session > > description it receives as the answer, and MUST ignore any > > session descriptions in subsequent responses to the initial > > INVITE." > > Does that mean if "Invite" contains SDP offer, the answer SDP MAY be in "180 > ring" and not in "200 OK"? I think part 1 and part 2 are inconsistent. > > The attached sequence chart is the real problem we meet. Sx1 sends "bye"to > sx2 after the "200 > OK" because there is no SDP answer in "200 OK". But the producer of sx2 > argues that the SDP answer is in "180 ring" already. No need to repeat it > in "200 OK". Could you please tell me who is right? MUST 200 OK contain > SDP? Thank you very much. > > Sx1 xs2 > > ====1 invite(SDP) ====> > > <====2 100 trying ==== > > <====3 180 ringing(SDP)==== > > ====4 prack ====> > > <====5 200 ack ====> > > <====6 200 OK (no SDP)====> > > > Best Regards****** > > Yuantao Zhang > > > _______________________________________________ > Sip mailing list https://www.ietf.org/mailman/listinfo/sip > This list is for NEW development of the core SIP Protocol > Use [EMAIL PROTECTED] for questions on current sip > Use [EMAIL PROTECTED] for new developments on the application of sip > -- Don't take life too seriously....Nobody comes out alive anyway
_______________________________________________ Sip mailing list https://www.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
