[sr-dev] why new tcp connection?

[Iñaki Baz Castillo]

El Viernes, 6 de Noviembre de 2009, Andrei Pelinescu-Onciul escribió:
> > Not at all per RFC 3261. Perhaps the hyper-complex draft-outbound states
> > that the TCP UA must bind on the source port from which the REGISTER is
> > sent, no idea. But for sure RFC 3261 doesn't say that.
> 
> Yes, according to 3261 the behaviour is correct. However if it doesn't
> support receiving requests on the same port it used to send the
> REGISTER or other requests it's broken in practice, since it would never
> work behind a NAT.

100% agree.


> It's like an udp UAC that has a different port in Via and expects new
> requests only on that port: it's perfectly valid according to 3261, but it
> will never work in practice due to NATs.

Yes, UDP asymmetric SIP clients. Fortunatelly they are dissapearing :)


 
> > > or add an alias parameter to its Via
> > > (assuming that the port in Via _is_ 5074).
> > > If it does add "alias" to the Via, make sure you have
> > > tcp_accept_aliases=yes in the config.
> >
> > What is an "alias" parameter in the Via header?
> 
> draft-ietf-sip-connect-reuse-00 - it's a parameter added to Via
> whend sending a request that means the remote side can alias the
> connection (add an internal ip:src_port as an alias for ip:via_port).
> The current version of the draft seems to be dealing only with TLS
> though (it looks like TCP alias is now in
> draft-jain-sip-transport-layer-connection-reuse-00).

Ok. so using "force_tcp_alias" then SR behaves as if the request contained 
"alias" in Via header and tcp_accept_aliases=yes in the config. So requests to 
that user are sent using an existing TCP connection. Now it's clear, thanks ;)




-- 
Iñaki Baz Castillo <ibc at aliax.net>