[CUWiN-Dev] IIT VoIP lab - requests?

[David Young]

On Sun, Feb 26, 2006 at 03:09:41AM -0500, William Waites wrote:
> On Fri, Feb 24, 2006 at 01:11:21PM -0600, Paul Smith wrote:
> > 
> > We spoke yesterday and decided to focus on two variables for testing: one is
> > varying TOS in the IP header to prioritize SIP protocol packets over say
> > HTTP, and the other is setting up a multi-hop network in the lab and seeing
> > what happens to a SIP session when a node goes down.
> 
> Hi Paul. Greetings from Jo'burg!
> 
> Just a note about diffserv and VoIP.
> 
> Strictly speaking, any type of diffserv should be applied to the
> RTP packets, not the SIP packets. In an environment where you don't
> have particular control over the client software (i.e. outside the lab)
> it might be necessary to re-write the headers to set a known TOS value
> at the ingress gateway. But you can't just, say, match on port 5060
> since the RTP streams will use random UDP ports and it's these flows
> that we really care about.

Yipe!  Let us hope the RTP streams have the correct TOS set.  I'm not too
keen on ingress routers rewriting headers.  It's not standards-compliant
behavior, for one thing, and it adds unwelcome packet-forwarding overhead.

Dave

-- 
David Young             OJC Technologies
dyoung at ojctech.com      Urbana, IL * (217) 278-3933