Hi, My SIP server has an interop problem with a third party SBC when sending large INVITEs in UDP. The INVITE message size is 1342 bytes, and the RFC says that messages over 1300 bytes should be sent using a reliable protocol like TCP. This is the section of the RFC I am referring to: If a request is within 200 bytes of the path MTU, or if it is larger than 1300 bytes and the path MTU is unknown, the request MUST be sent using an RFC 2914 <http://www.faqs.org/rfcs/rfc2914.html> [43] congestion controlled transport protocol, such as TCP. If this causes a change in the transport protocol from the one indicated in the top Via, the value in the top Via MUST be changed. This prevents fragmentation of messages over UDP and provides congestion control for larger messages. However, implementations MUST be able to handle messages up to the maximum datagram packet size. For UDP, this size is 65,535 bytes, including IP and UDP headers.
Doesn't the second part of the paragraph contradict the first part? Why should the receiving side's implementation accept the large packet if the sender is not supposed to send it? The third party SBC doesn't send any response for the message other than 100 Trying. Should it accept my INVITE? what response should it send in this case? One last thing - the third party SBC doesn't support TCP. Is there any other "correct" way to send the INVITE? is TCP support mandatory in RFC 3261? Hagai. _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
