[Sip-implementors] RE: CANCEL Processing by PROXY - No Response context is present.

[uprakash]

Hi Kannan,   Thanks for the reply. Please see my comments inline..   -----Original Message----- From: Natesan Kannan [mailto:[EMAIL PROTECTED] Sent: Thursday, November 13, 2003 11:33 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: [Sip-implementors] CANCEL Processing by PROXY - No Response context is present.   CANCEL is to be forwarded statelessly. This implies that no (481) response could be sent for that, as sending response would mean creating a server transaction state for CANCEL. So the question should be, if we can return a 481 OR statelessly forward CANCEL.   Consider a case with two proxies A, and B.   UA -> Proxy A -> Proxy B ---< fork to UAS 1 and UAS 2   Let us say, UAS1 and UAS 2 first send 1xx, and then UAS 1 sends a 2xx. Now, the response context in Proxy A is removed, whereas there is a response context in Proxy B, for the UAS 2 client branch.   Now, if a CANCEL is received at Proxy A, it must be forwarded to Proxy B, for Proxy B has a valid INVITE transaction to CANCEL.     [Prakash]=. I get the scenario,but I guess that for this specific scenario, we could not change the implementation(which is generic). Since this would mean that for a Stateful proxy, if an incoming CANCEL is got, and there is no matching transaction, then a 481 would never be sent and instead CANCEL be forwarded statelessly always.   I think that for this scenario, since the Proxy has forwarded a 200 response, it cud send a 481 for CANCEL rather. Also in the RFC, it is mentioned that It MUST statelessly forward the CANCEL request (it may have statelessly forwarded the associated request previously).   Hence I guess that they mean a different scenario here.But I am not able to understand or figure out the scenario. Also I am not able to get how to test this scenario.   Please let me know if I am getting something wrong.   Thanks, Prakash.   -Kannan   As an aside, this scenario described above could only be because of a 2xx/CANCEL cross-over between Proxy A and UAC. ***************************************************************** This e-mail and its attachments contain confidential information from HUAWEI, which is intended only for the person or entity whose address is listed above. Any use of the information contained herein in any way (including, but not limited to, total or partial disclosure, reproduction, or dissemination) by persons other than the intended recipient(s) is prohibited. If you receive this e-mail in error, please notify the sender by phone or email immediately and delete it! ***************************************************************** ----- Original Message ----- From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Wednesday, November 12, 2003 11:40 PM Subject: [Sip-implementors] CANCEL Processing by PROXY - No Response context is present.   Hi All,   I have a doubt in Section 16.10 on CANCEL Processing: [From RFC3261] =>If a response context is not found, the element does not have any knowledge of the request to apply the CANCEL to. It MUST statelessly forward the CANCEL request (it may have statelessly forwarded the associated request previously).   This is, after a SERVER TRANSACTION has been created for CANCEL and there is no matching response context. Hence, in this case, Proxy has to send 481 for CANCEL and forward the CANCEL statelessly??? Is this what the RFC says here?   UAC                PROXY                 UAS   -------CANCEL---�   �------481(???)-----                           ----CANCEL(???)--�(statelessly forwarded by Proxy)   Please clarify.   Thanks & regards, Prakash.   _______________________________________________ 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