RE: [BEHAVE] BoF request: STUN Control Usage

> Any idea how many of the deployed SIP servers use UDP? 

There is some information from SIPit 20,
https://www.sipit.net/SIPit20_Summary but of course that
lacks market share information.

> In my 
> understanding, more and more implementations were switching 
> to TCP because SIP messages were hitting up against the 1500 
> byte MTU limit for UDP. 

Based on that SIPit information, 71% claimed to work fine
with fragmented UDP packets and 10% didn't know.  I guess the
remainder (19%) know they break with fragmented UDP.  I dunno
what those implementations plan to do -- maybe choose a 
better IP stack?

Additionally, under high traffic rates from a single IP 
address (such as a bunch of SIP clients behind a single NAPT), 
draft-heffner-frag-harmful describes problems with reassembly
which I doubt are sufficiently appreciated by those running
SIP over UDP.

> Maybe the wireless guys are using UDP?  I never really considered
> using the UDP implementation myself just because I didn't see the
> point.  I guess the point would be better performance, but the added
> complication doesn't seem worth it.
> 
> I've even heard talk of excluding UDP altogether if we were 
> to write SIP over again.  I bring this up because the double 
> CRLF keep alive for TCP with SIP outbound is a really trivial 
> addition.  If almost everyone's using TCP, then your 
> reasoning above for STUN control breaks down. 

To summarize, I believe you're saying if UDP keepalives create 
too much load on your server or network, just use TCP.

-d

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