That depends on the UAC implementation. The UAC may use a user interface to let the caller decide, if it is capable of handling multiple appearances. Otherwise, it can set up the call after the first 200 Ok and when a second 200 OK is received it can send BYE after ACKing it. I don't understand your reference to the proxy behavior based on UAC enabling multiple dialogs. Where is this mentioned?
----- Original Message ----- From: "Wei BJ Lu" <[EMAIL PROTECTED]> To: "A Venkatraman" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Thursday, November 15, 2001 8:37 PM Subject: RE: [Sip-implementors] How does forking proxy handle To Tag in errorresponse selection? > > I have noticed the bis says proxy only forwards 2xx responses. But I still > have the doubt: If the UAC does not enable multiple dialogs, then what > should > it do on the arrival of multiple 200 responses? > > -Lu Wei > > > > > "A Venkatraman" > <[EMAIL PROTECTED]> To: Wei BJ Lu/China/IBM@IBMCN, "McMurry, Kathleen" > Sent by: <[EMAIL PROTECTED]> > [EMAIL PROTECTED] cc: <[EMAIL PROTECTED]> > lumbia.edu Subject: RE: [Sip-implementors] How does forking proxy handle To Tag > in er rorresponse selection? > > 2001-11-16 09:20 > Please respond to "A > Venkatraman" > > > > > > a. How does a UAC enable multiple dialogs? > b. The proxy only forwards all 200 class final responses. See line 2345 of > bis-05 pdf. > Also, see line 2423 which specifies that a proxy should send CANCEL on > all legs that sent a provisonal but no final response. > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]]On Behalf Of Wei BJ Lu > Sent: Thursday, November 15, 2001 6:58 PM > To: McMurry, Kathleen > Cc: [EMAIL PROTECTED] > Subject: RE: [Sip-implementors] How does forking proxy handle To Tag in > er rorresponse selection? > > > > I have some doubt on "the proxy should select the best response from the > ones it has > received and send it to the OUA". I think it it not always true. To my > understanding, > the behaviour of a forking proxy on receiving final responses should be > different > under two circumstances: > > a. If the UAC does not enable multiple dialogs(call-legs), the proxy > should forward > the best final response upstream and cancel all the unfinished forking > branches. > > b. If the UAC enable multiple dialogs, the proxy should forward all the > final > responses to the UAC. Since on the UAC's side, different To tag means > different dialog. > When 180 with To tag u1 and u2 comes, the UAC will create two dialogs. If > the proxy > only forward 486(this tag u1) to the UAC, the UAC will only terminate one > dialog and > the other dialog will keep ringing. > > -Lu Wei > > > > > > "McMurry, Kathleen" > <[EMAIL PROTECTED]> To: "'Bob > Penfield'" <[EMAIL PROTECTED]>, A Venkatraman > Sent by: > <[EMAIL PROTECTED]>, [EMAIL PROTECTED] > [EMAIL PROTECTED] cc: > lumbia.edu Subject: RE: > [Sip-implementors] How does forking proxy handle To Tag > in er ror response > selection? > > 2001-11-16 04:02 > Please respond to "McMurry, > Kathleen" > > > > > > > > >-----Original Message----- > >From: Bob Penfield [mailto:[EMAIL PROTECTED]] > >Sent: Thursday, November 15, 2001 1:19 PM > >To: McMurry, Kathleen; A Venkatraman; [EMAIL PROTECTED] > >Subject: Re: [Sip-implementors] How does forking proxy handle To Tag in > >er ror response selection? > > > >> > >> >> Suppose a proxy forks a request from UAC to uas1, uas2, > >> >> and each returns a 18x, with tag u1 and u2 respectively, which are > >> >> forwarded, as is, to UAC, > >> >> and then uas1 returns a 486 with tag u1 and uas2 returns 500 with tag > u2 > >> >> Proxy picks best response 486 to return to UAC. > >> >> > >> >> Question: > >> >> Will the TO tag in the 486 reponse be u1? Or, will there be no TO > tag. > >> >> Is this implementation specific or does the protocol specify this > >> >anywhere? > >> >> > >> >Based on section 16.6 on bis-05, the tag received in the response is > >> >preserved when the selected response is forwarded to the UAC. > Therefore, > it > >> >would be u1 for your example. The proxy is not allowed to modify the To > >> >header in the forwarded response. > >> > >> A 2xx response is the only type of response that is truly "forwarded" by > >the > >> proxy. Any non-2xx response is really hop by hop. Therefore, in your > >> example, the proxy will add its own To tag when it responds to the UAC. > >> Niether u1 or u2 would be used. > > >Section 16.6 of bis-05 explicitly forbids the proxy from adding its own > tag. > >It is not a UAS in this case. The proxy is suppose to select the best > >response from the ones it has received and forward that response to the > UAC. > > > I agree that the proxy should select the best response from the ones it has > received and send it to the OUA. I also agree that the spec. does not > clarify the two different cases well. > > In the case of a 2xx response, the proxy forwards the response to the OUA > leaving the To tag alone. For a non-2xx response however, the To tag is > used to match the corresponding ACK for each hop. Therefore, when the > non-2xx response is received by the proxy, it should ACK the UAS with the > To > tag that was added by the UAS. But when the proxy sends the response to > the > UAC, the proxy should use a To tag that it generates so that it can > determine that the corresponding ACK is meant for the proxy and should not > be forwarded. > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > > > > > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > > > > > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
