(Some details removed!) INVITE f...@bar Via: blah;branch=z9hG4bK-foo CSeq: 123 INVITE
CANCEL sip:f...@bar Via: blah;branch=z9hG4bK-foo CSeq: 123 CANCEL Yes, the branch for the Cancel should be the same as for the INVITE it is cancelling as well as the numeric part of the CSeq (amongst other things - see RFC3261 section 9.1 for details). But having a different method part for the CSeq allows a cancel to be "identified and processed as a transaction in its own right" (quote from aforementioned section 9.1). Michael Attila Sipos wrote: > 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. Any unauthorised distribution or copying is > strictly prohibited. If you receive this transmission in error, please > notify the sender by reply email and then destroy the message. Opinions, > conclusions and other information in this message that do not relate to > official business of Mascon shall be understood to be neither given nor > endorsed by Mascon. Any information contained in this email, when > addressed to Mascon clients is subject to the terms and conditions in > governing client contract. > > Whilst Mascon takes steps to prevent the transmission of viruses via > e-mail, we can not guarantee that any email or attachment is free from > computer viruses and you are strongly advised to undertake your own > anti-virus precautions. Mascon grants no warranties regarding > performance, use or quality of any e-mail or attachment and undertakes > no liability for loss or damage, howsoever caused. > > > > _______________________________________________ > 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
