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RE: [reSIProcate] symmetric signalling


By default, resiprocate will use symmetric signaling for UDP transports.

Furthermore, resiprocate will insert the rport parameter into the Via. If
the downstream element understands rport it will fill in the port that the
request was sent from. This will allow your downstream element to reply to
the response to the port that it was received from - assisting traversal of
NATs when using UDP.

Take this example. A resip UAC is behind a NAT and sends a request to a
proxy on the public network. If the proxy does not support the rport
parameter it will try to reply to the sent-port in the Via which will not
work since the NAT may have mapped the sent port to some other port on the
NAT. If the proxy supports rport, it will send the response to the port on
the NAT that sent the request and the NAT will usually forward the response
correctly back to the sender.




> -----Original Message-----
> From: resiprocate-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:resiprocate-devel-bounces@xxxxxxxxxxxxxxxxxxx]On Behalf Of
> WAGNER, Jerome (Consultant)
> Sent: Thursday, August 05, 2004 9:44 AM
> To: resiprocate-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [reSIProcate] symmetric signalling
>
>
> Hello,
>
> I'm looking at the NAT issue.
> Do you think it is simple to use the resip socket transport
> handling to force "symmetric signalling" ?
> (signalling going in and out on the same port)
>
> is there an example in the resip examples or in the DUM examples ?
>
> thanks
> Jérôme
>