> bis-05 gives an algorithm on how to create and add a > Record-Route header using Contact or From header by a proxy > (for allowing spirals). Also given is the modification of > this header in the responses being forwarded upstream. The > Record-Route header in the responses that was forwarded to the > upstream comes back to proxy in the form of Request-URI in ACK > (and subsequent requests). > > As per matching rules of requests to server transactions in > section 17.2.3 the ACK matches with the INVITE if Request-URI, > From, Call-ID, CSeq method and top Via header match those of > the INVITE that created the > transaction......................... > > Because of the way the Record-Route was formed using the Contact > header of the response the Request-URI of the ACK does not > match with the INVITE's.
Indeed it does not. It does not need to, since the ACK is considered a distinct transaction. (ACKs for non-2xx final responses to INVITEs are logically considered to be part of the INVITE transaction, whereas ACKs for 2xx to INVITEs are considered to be in a transaction of their own.) > I apologize if it was already discussed. Can somebody explain > me what am I missing ? The only reason the ACK would be needed to match is so that the right server transaction machine can be located to quench retransmission of an INVITE response. In the case of a proxy, it does not retransmit a 2xx to an INVITE, so it never needs this association. - Jo. _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
