> On 04 Aug 2015, at 13:14, Chad <ccolu...@hotmail.com> wrote: > > Hi list, > I need a little help, I am a business owner trying to get Kamailio up and > running as a SIP load balancer. > I hired a Kamailio consultant to help me do so, but Kamailio is not working > and I am getting conflicting information. > > My Kamailio consultant and my VOIP provider are telling me 2 different things > and I don't know which one is right. > > Kamailio sends SIP traffic to the VOIP provider with 2 VIA headers like this > (in this order): > Via: SIP/2.0/UDP > 10.10.10.254;branch=z9hG4bK7291.6a0bbd2e8fd639a47d7d2de606779e47.0. > Via: SIP/2.0/UDP > 209.170.201.25:5060;received=10.10.10.102;branch=z9hG4bK742dc03d;rport=5060. > > The VOIP provider says that is incorrect because they are supposed to reply > back to the topmost VIA header so they reply to the 10.10.10.254 IP (which is > not public) and the call ends. > The VOIP provider says Kamailio should send the VIA headers like this instead: > Via: SIP/2.0/UDP > 209.170.201.25:5060;received=10.10.10.102;branch=z9hG4bK742dc03d;rport=5060. > Via: SIP/2.0/UDP > 10.10.10.254;branch=z9hG4bK7291.6a0bbd2e8fd639a47d7d2de606779e47.0. > > My Kamailio consultant says the way we are sending it is right and that the > VOIP provider is processing the call incorrectly. > > I read that the SIP proxy is supposed to remove the internal header from the > 1st example above based on this RFC: > https://tools.ietf.org/html/rfc3261#section-16.7 > Item: 3. Via > "The proxy removes the topmost Via header field value from the response.” That applies to response forwarding. > > If that applies to this situation (which I don't know if it does) then > Kamailio should be removing the 10.10.10.254 VIA line and only sending 1 VIA > header like this: > Via: SIP/2.0/UDP > 209.170.201.25:5060;received=10.10.10.102;branch=z9hG4bK742dc03d;rport=5060. > > Which would sort of make the VOIP provider right in that the topmost VIA line > would then be the external IP, but how they said to fix it (reversing the VIA > lines) is wrong. The response is sent to the topmost, leftmost VIA header value. The proxy adds it’s own address on TOP of other values when forwarding a request. That’s the address used for sending responses. See section 18.2.2 “Sending Responses” of RFC 3261.
What I don’t understand is how the via’s got in a different order. Kamailio does this right by default. It’s a very basic operation, but could be something related to the handling of public/private IP addresses that got wrong. /O _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
