[Serdev] RFC 3261 Section 18.1.1

[Evan Borgström]

Hey guys,

	Does SER conform to Section 18.1.1 of RFC 3261 which states:

    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 [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.



	We have been noticing that some clients are putting a bunch of extra 
headers in (for things like byte counters ala the Cisco IP phones) and 
we've been seeing some fragmentation from them. I've begun using 
consume_credientials much more to try and size down the messages that do 
not need the Auth/Proxy-Auth headers any more which seems to be helping 
a bit but I'm still curious about is SER would auto-magically switch 
protocols to deal with this.

-Evan