> No SIP agent should ever receive a > UDP packet larger than 1500 bytes. > RFC 3261, section 18.1.1 says:
I agree that RFC3261 provides a mechanism to avoid UDP fragmentation; however fragmentation does occur. Some SIP devices do not yet support TCP; and some users/administrators do not activate TCP. Additionally I do not think anyone has documented a way to send large responses over TCP when the request was received over UDP. The SIP agent must be able to receive large UPD messages. Section 18.1.1 mentions the following: "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." SIP ALGs, STUN servers, etcetera, must allow UDP fragmentation unless they are intentionally sacrificing interoperability for security reasons. _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
