[asterisk-users] Microsoft Office Communications Server

[Kristian Kielhofner]

On Mon, Mar 10, 2008 at 6:38 PM,  <mgraves at mstvp.com> wrote:
> What is the logic of them using SIP over TCP? Is this a broad industry
>  trend? Or just the latest attempt to get around SIP/NAT issues?
>
>  Michael Graves
>  mgraves <at> mstvp.com
>  o(713) 861-4005
>  c(713) 201-1262
>  sip:mjgraves at pixelpower.onsip.com
>  skype mjgraves
>  FWD 54245
>

I would imagine it's because they plan on doing all kinds of "neat"
stuff with SIP including video, TXT, Windows Updates, who knows...
SIP over UDP has some pretty serious packet fragmentation issues.  If
you end up with a large enough SDP or something that causes a SIP
packet to grow larger than the smallest MTU in the path between your
two endpoints it doesn't work (no fragmentation support with SIP over
UDP).  SIP over TCP does not have this problem.

Also, you need SIP TCP support for TLS...

-- 
Kristian Kielhofner