[EMAIL PROTECTED] wrote: > Thanks paul! > Now what I am concerned with is: why in this case, the 180 Ringing is > not permitted to carry SDP? Based on what kind of consideration? Thanks!
Because it doesn't follow any of the specified patterns for conveying offers and answers. Look at http://www.ietf.org/internet-drafts/draft-ietf-sipping-sip-offeranswer-06.txt Paul > Alex Zhang > ESN: 6-554-8782 > > > -----Original Message----- > From: Paul Kyzivat [mailto:[EMAIL PROTECTED] > Sent: Tuesday, March 04, 2008 11:48 PM > To: Alex Zhang (GDNTRND) > Cc: [EMAIL PROTECTED]; [email protected] > Subject: Re: [Sip-implementors] what about swich behaviors when it > receivesan180 Ringing with an new SDP offer? > > > > [EMAIL PROTECTED] wrote: >> Hi Paul, >> >> I think she is querying what the UAC will react to the 180 ring >> message with a SDP offer. As we know, if the initial invite contains >> the SDP offer, then the first 18x reliable provisionable response >> could carry the answer. This 1st 18x could be the 183 session >> progress, so will the subsequent 180 ring message with the SDP offer >> be rejected or accpeted by the PRACK message? > > So is the following: > > UAC UAS > | INVITE w/offer1 | > |-------------------->| > | Rel 183 w/answer1 | > |<--------------------| > | PRACK | > |-------------------->| > | 200 (PRACK) | > |<--------------------| > | Rel 180 w/SDP | > |<--------------------| > | ??? | > |-------------------->| > > the case you are concerned with? > > In that case the 180 is not permitted to contain SDP, so this is an > error case. It is however not so clear what to do about it. What you > want here is a PRNACK, but we don't have that. So you either: > - withhold the PRACK, which will cause the response to be > retransmitted until it times out and fails the dialog. > - send the PRACK, then send CANCEL or BYE to kill the call > - send the PRACK and cope with the revised SDP in some way. > (If it is the same as answer1 then it might make sense to > ignore it. If it is different than answer1 it isn't at all clear > what to do.) > > Because this is an error case I think you can choose to do as you wish. > > Paul > > > >> Alex Zhang >> ESN: 6-554-8782 >> >> >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of >> Paul Kyzivat >> Sent: Monday, March 03, 2008 9:24 PM >> To: christina yuen >> Cc: [email protected] >> Subject: Re: [Sip-implementors] what about swich behaviors when it >> receivesan 180 Ringing with an new SDP offer? >> >> christina, >> >> I'm sorry, but I can't figure out what you are asking below. >> >> If you haven't already, see if >> >> http://www.ietf.org/internet-drafts/draft-ietf-sipping-sip-offeranswer >> -0 >> 6.txt >> >> answers your question. >> >> Paul >> >> christina yuen wrote: >>> My understanding is >>> >>> 1> if an SDP offer received in a SIP request, such as all media >>> 1> streams >>> in the SDP offer, => the SDP answer is returned in a 488 Not >>> Acceptable Here response and a SIP607 log is generated. >>> >>> 2> If an SDP offer received in a provisional response, such as >>> 2> all >>> 2> media >>> streams in the SDP offer, => it must be rejected, the SDP answer is >>> returned in the PRACK. >>> >>> >>> >>> Now an new SDP offer is received in a provisional response, 180 >>> Ringing, then the switch should reject the SDP offer in PRACK. Do you > >>> think it is right? Thanks. >>> >>> >>> >>> Christina >>> _______________________________________________ >>> Sip-implementors mailing list >>> [email protected] >>> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors >>> >> _______________________________________________ >> Sip-implementors mailing list >> [email protected] >> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors >> >> _______________________________________________ >> Sip-implementors mailing list >> [email protected] >> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors >> > > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
