[Kamailio-Users] switch to TCP when UDP message is bigger than MTU

[Andreas Heise]

Hi Klaus,

Klaus Darilion schrieb:
> Hi Sandro!
>
> If you just need it for testing then you could use the approaches 
> mentioned in the other emails.
>
> But for a production system you usually do not want this feature. 
> Practically this paragraph from RFC 3261 is non-sense as it brakes 
> communication with SIP clients.
>
> Residential customers SIP clients are mostly behind NAT and often do not 
> even support TCP. Thus, automatic switching to TCP will cause problems 
> as you can not reach the clients anymore.
>
>   
you are right, but RFC 3261 says also...

18.2.1 Receiving Requests

"For any port and interface that a server listens on for UDP, it MUST 
listen on that same port and interface for TCP.
This is because a message may need to be sent using TCP, rather than 
UDP, if it is too large."

... so the SIP clients you mentioned are not conform with RFC 3261!

regards,
Andreas