Hi Rhys, In my mail what i mentioned is true only when the incoming message has a via parameter with the branch as well as magic cookie. What the proxy does is adds its own via with a different branch parameter and forwards the message. I guess this explanation is not what u r looking for!!
Now if we consider the scenario when the incoming message does not contain the branch parameter in Via header or branch parameter without the magic cookie then there are number of outcomes that are possible. It actually depends on what type of incoming message the Proxy is receiving(INVITE,ACK,CANCEL,BYE...) and what is the state of the call(proceeding/completed). Depending on this scenario the proxy either discards the request or repeats its last response. Consider the case for an incoming CANCEL request,Proxy server is in INVITE Proceeding state, when receives a CANCEL, including a Via header set with no branch parameter but with the Request-URI, To tag, From tag, Call-ID, CSeq number and top Via header identical as in the INVITE to be cancelled, answers to the original INVITE, request with a Request Terminated (487 Request Terminated) response. Consider another case when the Proxy receives an ACK without branch parameter in the Via header. Then in this case it simply discards the message and does not forwards it. Thus there are a number of scenarios possible in this case. Please clarify if any thing that i have mentioned smells fishy. Regards, Atul -----Original Message----- From: Rhys D Ulerich [mailto:[EMAIL PROTECTED] Sent: Wednesday, August 18, 2004 5:57 PM To: Atul Khandelwal Subject: RE: [Sip-implementors] Behavior when Via lacks a branch parameter Hi Atul, Thanks for responding. Where did you find this behavior specified? - Rhys __________________________________ Rhys Ulerich Telecommunications Solutions Software Development Email: [EMAIL PROTECTED] Office: 512-838-1428 IBM Software Group - Austin, TX "Atul Khandelwal" <[EMAIL PROTECTED]> 08/17/2004 11:38 PM To Rhys D Ulerich/Austin/[EMAIL PROTECTED], <[EMAIL PROTECTED]> cc Subject RE: [Sip-implementors] Behavior when Via lacks a branch parameter Hello, As far as my knowledge goes the proxy adds a branch parameter itself when it detects that the incoming message does not have a branch parameter. The same thing goes with the magic cookie also. Please let me know if I am wrong. Regards, Atul -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Rhys D Ulerich Sent: Wednesday, August 18, 2004 3:34 AM To: [EMAIL PROTECTED] Subject: [Sip-implementors] Behavior when Via lacks a branch parameter Hello, What's the correct (RFC 3261) behavior when receiving a Via without a branch parameter (i.e. going against 8.1.1.7)? Another question is what to do when there is a branch parameter that doesn't include the magic cookie? Thanks, Rhys __________________________________ Rhys Ulerich Telecommunications Solutions Software Development Email: [EMAIL PROTECTED] Office: 512-838-1428 IBM Software Group - Austin, TX _______________________________________________ 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
