The response to the UAC does contain the Via that was in the request sent by the UAC. It contains the branch tag that is used for transaction matching.
See section 8.1.3 and 17.1.3 of RFC 3261. cheers, (-:bob Robert F. Penfield Chief Software Architect Acme Packet, Inc. 130 New Boston Street Woburn, MA 01801 [EMAIL PROTECTED] ----- Original Message ----- From: "Patrick Lam" <[EMAIL PROTECTED]> To: "'Patrick Lam'" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Monday, June 09, 2003 5:57 AM Subject: RE: [Sip-implementors] Request URI for INVITE for a B2BUA (acting asan ALG)?? > At the last part of my question, I actually mean a 'response', instead > of a 'request'... Therefore, it should be: > > "In addition, as a B2BUA, when the ALG receives a 200 OK, is the > response supposed to contain a Via header at all? (A UAC is not supposed > to receive a response with the Via header, right?)" > > Thanks. > > Patrick > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Patrick > Lam > Sent: Monday, June 09, 2003 5:47 PM > To: [EMAIL PROTECTED] > Subject: [Sip-implementors] Request URI for INVITE for a B2BUA (acting > as an ALG)?? > > Dear all: > > I am implementing an ALG (for NAT/Firewall Traversal) using a B2BUA > design. I am just wondering what the call flow looks like. Here is > what I plan to do: > > User A <--> SIP Proxy <--> ALG (B2BUA) <--> Firewall/NAT <--> User B > > Is User A places a call, the INVITE will be routed through the proxy to > the ALG. How should the proxy populate the Request URI? > > Should it be: > > 1. INVITE sip:[EMAIL PROTECTED] SIP/2.0 > 2. INVITE sip:[EMAIL PROTECTED] SIP/2.0 > 3. INVITE sip:[EMAIL PROTECTED]; maddr=alg.inside.com SIP/2.0 > > ? > > Is any of the above looking good? > > In addition, as a B2BUA, when the ALG receives an INVITE, is the request > supposed to contain a Via header at all? (A UAS is not supposed to > receive a request with the Via header, right?) > > Thanks very much in advance, > > Patrick > > > > > _______________________________________________ > 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
