Hi sharad, Thanks for your opinion. However the proxy must maintain the dialog for some minimal time at least. This is because it might have to take care of a retransmission scenario where the User-Agent sends the same REGISTER again. The proxy in this case can send a stored response back to the User-Agent instead of processing the REGISTER for the 2nd time.
In the scenario that I have described below, there is nothing to deter the User-Agent from having the same call-id and Cseq in the REGISTER when it restarts. That leaves me with some more questions : (1)So what actually constitutes a dialog ? Is it composed of the following: (a)From( URI+ tag and NOT any other parameter) (b)To( URI+ tag and NOT any other parameter) (c)Call-ID (2)What should be the minimal time for which a proxy must maintain a REGISTRATION dialog to take care of retransmission? Thanks and Regards Prakash GS -----Original Message----- From: Sharad Goklani [mailto:[EMAIL PROTECTED]] Sent: Tuesday, July 02, 2002 12:56 PM To: Prakash GS; [EMAIL PROTECTED] Cc: 'Nirmalya (E-mail)' Subject: RE: [Sip-implementors] Refreshing Registration query I guess the proxy/registrar will/should *not* be maintaining any information residing in the REGISTER request, except, of course, the From (excluding tag), Contact & Expires fields. The tag parameter is actually significant when there is a possibility of 2 or more REGISTER requests, from different sources, having the same call-id, arriving at a proxy at the same time. In this case, however, once the first REGISTER is executed, the proxy forgets about the dialog, and thus the next request will be treated as a new/update request and it will update the registration expiry time. Sharad -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Prakash GS Sent: Tuesday, July 02, 2002 11:23 AM To: [EMAIL PROTECTED] Cc: Nirmalya (E-mail) Subject: [Sip-implementors] Refreshing Registration query Hi all I have a doubt regarding a refreshing registration. Assume that a User-Agent A has registered using the following REGISTER message with a proxy+registrar. REGISTER sip:proxy.com SIP/2.0 Via:SIP/2.0/UDP ua1:5060 From:<sip:3251@ua1;User=phone>;tag=278100000000000000000715 To:<sip:3251@ua1;User=phone> Contact:<sip:3251@ua1;User=phone> Call-ID:01B2270D4881400000000000@ua1 CSeq:1 REGISTER Expires:180 A goes down and comes up again. It attempts to register and sends a registration with the SAME call-id and Cseq as before but with a DIFFERENT tag in the From header . How should the proxy treat the REGISTER and why ? Should it : (a)Consider the REGISTER as a retransmission from A or (b)Should it keep track of the 'Tag' and so treat the request as a new REGISTER ? In essence what is the role of the 'Tag' field in such a scenario, if any ? Thanks Prakash GS _______________________________________________ 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
