Hello Hawn, pl. check the replies inline. Thanks, Manoj
-----Original Message----- From: [EMAIL PROTECTED] [mailto:sip-implementors-admin@;cs.columbia.edu]On Behalf Of Dong, Hwan Sent: Friday, October 18, 2002 5:40 PM To: [EMAIL PROTECTED] Subject: [Sip-implementors] 2 questions on toTag in 200-for-CANCEL Hi, First, I have some doubt on the sequence of Section 3.8 of draft-ietf-sipping-basic-call-flows-01.txt: User A issues a CANCEL (F9) without To tag, and receives 200-CAN response (F10) from Proxy 1. There is no To tag in the 200-CAN. But there is different specification in 3261, section 9.2: "... The UAS answers the CANCEL request itself with a 200 (OK) response. This response is constructed following the procedures described in Section 8.2.6 ..." And in Section 8.2.6.2 says: "... However, if the To header field in the request did not contain a tag, the URI in the To header field in the response MUST equal the URI in the To header field; additionally, the UAS MUST add a tag to the To header field in the response..." It seems 3261 mandates toTag in 200-CAN. Manoj>> Yes, the 200-OK(CANCEL) MUST contain To tag and this MUST be same as the To Tag in 1xx-Response to INVITE. In that Call Flow doc, it was a flaw and I belive Alan has already confirmed that. Second, in section 9.2: "the UAS answers the CANCEL request itself with a 200 (OK) response. This response is constructed following the procedures described in Section 8.2.6 noting that the To tag of the response to the CANCEL and the To tag in the response to the original request SHOULD be the same. " So it is saying at UAS, the toTag in CANCEL should be same as that in earlier 1xx, right? Manoj>> No. there should not be any To-tag in CANCEL, the above lines are sayiong about the To tag in the Respone to the CANCEL. There must be To-tag in 200-OK(CANCEL) and must be same as the To Tag in 1xx-Response to INVITE. if u will refer RFC-3261, section 9.1: it says "The following procedures are used to construct a CANCEL request. The Request-URI, Call-ID, To, the numeric part of CSeq, and From header fields in the CANCEL request MUST be identical to those in the request being cancelled, including tags....." So since intial INVITE never contains a To tag, therefore CANCEL will not contain To Tag. But how about stateful PROXY, proxy may not remember/keep the toTag in earlier 1xx, so proxy may have to generate a new toTag for 200-CAN, which would be different from toTag in 1xx. Manoj>> since it is a stateful proxy, it should remember the To tag in 1xx and MUST use the same in 200-OK(CANCEL) toTag is used to identify a dialog, however. Shouldn't the toTag in one dialog cycle be SAME? Otherwise, what is the purpose of toTag in 200-CAN? Manoj>> Yes, the To tag of 200-OK(CANCEL)is of course same as in 1xx. Thanks for your help, Hwan _______________________________________________ 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
