moving to sip implementors. wangshan wrote: > Hello,All > > I am a freshman of SIP, When I read the RFC3261, I have a question > about the section "17.1.3 Matching Responses to Client Transactions". > this section said: > > ************************************************************ > 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. > > A response that matches a transaction matched by a previous response > is considered a retransmission of that response.
I am not sure what version you are looking at, but that last sentence is not in rfc3261. > ************************************************************ > so consider the following situation > > UA PROXY(FORK) UA1 UA2 > > --F1-INVITE----> ---F2-INVITE--> > ------F3----------INVITE----> > > <-F4-18X(UA1)---- > <-F5------------18X(UA2)---- > > <-F6-18X(UA1)---- > <-F7-18X(UA2)---- > > UA1 and UA2 both send 18x, F4 & F5, Proxy should forward all > provisional response back, so F6 & F7 are transmission to UA,but both > message(F6 & F7) have the same Via header ,so have the same branch ID, > given UA received F6 first,as per the matching rules metioned above, F7 > will be considered as a retransmission of F6. Is this situation right? This is why we removed the definition of retransmission. The transaction machines will properly pass both provisionals upstream. > more, if F6 is unreliable response, but F7 is reliable reponse which > need a PRACK, how to do? > > > If my understanding is wrong, please tell me. thanks ahead. To properly determine if a provisional response is a retransmission or a new one, you need a sequence number or something within the provisional response, and rfc3262 provides exactly that. This is why the definition of retransmit belongs there. -Jonathan R. -- Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Ave. Chief Scientist First Floor dynamicsoft East Hanover, NJ 07936 [EMAIL PROTECTED] FAX: (973) 952-5050 http://www.jdrosen.net PHONE: (973) 952-5000 http://www.dynamicsoft.com _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
