Thanks Ryan, Paul and Alex, Yes, I think PRACK with a SDP answer can give a graceful reply for the SDP offer of an 18x reliable provisional response. For it still in early state the call can be take down by CANCEL.
For Alex's concern, I think in the same dialog, any attibute to be updated by a request, such as re-INITIVE/UPDATE. If we accept a new SDP offer carried by reliable 18x response, it means the UAC has to send a request with a corresponding answer. Perhaps it is not good enought for SDPofer/answer model. At the same time, if UPDATE with a SDP offer is replied for the 180 Ringing there will be a transation loop. And it surely beyond the timer. So the way that just do not encourage a response with a SDP offer is simple and clear. Thanks, Christina UAC UAS | INVITE w/offer1 | |-------------------->| | 180 Trying | |<--------------------| | 183 (SDP answer) | |<--------------------| | PRACK | |-------------------->| | 200 OK(PRACK) | |<--------------------| | 180 Ringing(offer) | |<--------------------| | PRACK(answer) | |-------------------->| | CANCEL | |-------------------->| | 200 OK(CANCEL) | |<--------------------| | ACK | |-------------------->| On 3/5/08, [EMAIL PROTECTED] <[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! > > > > 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
