[OpenSER-Devel] TCP error

[Klaus Darilion]

Iñaki Baz Castillo schrieb:
> El Thursday 14 February 2008 17:46:45 Klaus Darilion escribió:
>> Either the Contact is wrong or the TCP session is gone.
> 
> Probably TCP session is gone, since I have never "Contacts" related problems 
> with UDP clients.

Depends on the SIP client and you NAT dedection methods. Eg. 
eyebeam/xlite is smart and learns the public TCP socket from Via header 
in response and then registers this contact. But for example SNOM is 
dumb - it uses STUN (of course this gives you only the public UDP port) 
and then uses the UDP port in the Contact, although the public TCP port 
will be different usually.

Except eyebeam/xlite I do not know any SIP client which handles TCP NAT 
traversal fine. Usually all other clients need a fix_nated_contact/register.

If you already do NAT traversal then it really maybe that the session is 
gone - some dumb phones register and then shut down the TCP connection. 
And other phones keep the TCP connection open but close it when a CRLF 
is received.

Conclusion: Currently SIP clients do not handle TCP as good as UDP.

klaus

> 
>> I do fix_nated contact/register and nat-pinging for all TCP clients to
>> avoid any issues.
> 
> In my case I just do nat-pinging for natted contacts.
> 
> Regards.
> 
>