Yes of course, I was thinking of the CSeq number but of course you have to look at the method !! Thanks to everyone for replies, Attila
________________________________ From: Somesh S. Shanbhag [mailto:[email protected]] Sent: 02 March 2009 09:10 To: Attila Sipos; priyank luthra; [email protected] Subject: RE: [Sip-implementors] Branch parameter as transaction identifierv/sCseq RFC 3261 Section 17.1.3 17.1.3 Matching Responses to Client Transactions When the transport layer in the client receives a response, it has to determine which client transaction will handle the response, so that the processing of Sections 17.1.1 and 17.1.2 can take place. The branch parameter in the top Via header field is used for this purpose. A response matches a client transaction under two conditions: 1. If the response has the same value of the branch parameter in the top Via header field as the branch parameter in the top Via header field of the request that created the transaction. 2. If the method parameter in the CSeq header field matches the method of the request that created the transaction. The method is needed since a CANCEL request constitutes a different transaction, but shares the same value of the branch parameter. Somesh * Please do not take print out of this e-mail unless its absolutely necessary * -----Original Message----- From: Attila Sipos [mailto:[email protected]] Sent: Mon 3/2/2009 2:15 PM To: Somesh S. Shanbhag; priyank luthra; [email protected] Subject: RE: [Sip-implementors] Branch parameter as transaction identifierv/sCseq When you send the CANCEL, won't the branch be the same as in the INVITE? So I can't see what extra advantage is offered by the CSeq. Can you explain. ________________________________ From: Somesh S. Shanbhag [mailto:[email protected]] Sent: 02 March 2009 08:25 To: Attila Sipos; priyank luthra; [email protected] Subject: RE: [Sip-implementors] Branch parameter as transaction identifierv/sCseq CSeq method is used to identify the transaction along with branch, when a CANCEL request is processed. Somesh * Please do not take print out of this e-mail unless its absolutely necessary * -----Original Message----- From: [email protected] on behalf of Attila Sipos Sent: Mon 3/2/2009 1:53 PM To: priyank luthra; [email protected] Subject: Re: [Sip-implementors] Branch parameter as transaction identifierv/sCseq Simply: 1. transaction instance is created and a branch parameter is associated with it 2. the branch parameter is placed into a request 3. response is received with the same branch parameter 4. transaction instance can be destroyed As far as I can tell, you don't need to use CSeq to identify a transaction. I believe branch was not used by UA's in the orignal SIP RFC (RFC2543) so CSeq and Method was originally used to match transactions. However in RFC3261, branch is used by UA's so CSeq is not now needed for transaction matching. Regards, Attila -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of priyank luthra Sent: 02 March 2009 06:50 To: [email protected] Subject: [Sip-implementors] Branch parameter as transaction identifier v/sCseq Hi all, I would like to know why and how is a branch parameter in Via header able to identify a transaction, and if so, why do we need CSeq header to identify a transaction? -- Regards, Priyank _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors ________________________________ EMAIL DISCLAIMER : This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. 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