"xaled" <xa...@web.de> writes: > A client originates a session over TCP connection to proxy1 after having it > resolved as top priority outbound proxy from preconfigured edge.test.com > domain. Proxy 1 sends 200 Ok response with following Record-Route header: > > Record-Route: <sip:edge.test.com;transport=tcp;lr> > > Now client wants to send a reINVITE and instead of reusing the established > TCP connection to proxy1 it resolves edge.test.com over DNS again and this > time receives proxy2 as top priority outbound proxy. Having received proxy2 > with highest priority than proxy1 client sends in-dialog request to proxy2 > instead of reusing established TCP connection to proxy1. > > Now is there any recommendation for the preferential use of established TCP > connection to the proxy1 given that it is resolvable from edge.test.com?
If edge.test.com is resolved using SRV records, RFC 3263 and 2782 do not allow for prefering to reuse an existing connection -- 2782 prescribes that potential targets are tried in a particular order based only on the DNS information. If edge.test.com is resolved only using A/AAAA records, 3263 does not prescribe a priority order among the records, so the implementation can prefer to use the existing connection. RFC 5923 (Thanks, Brett, for making me aware of this!) is a more complicated matter. 5923 describes use for TLS only, but its procedures could be applied to TCP as long as they are only used by the connection initiator, that only the connection initiator creates an entry in its alias table. The larger system-design questions are worth considering. If the DNS for edge.test.com is adjusted to give higher priority to proxy2, doesn't that mean that the administrator *really wants* all new requests to go to proxy2 if possible? That would argue against reusing the TLS connection simply because its address/port is another target for the DNS name. Dale _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
