[CUWiN-Dev] IIT VoIP lab - requests?

[Paul Smith]

On 2/26/06, David Young <dyoung at pobox.com> wrote:
>
> 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.



Useful feedback, I'll pass it along to the Lab.

-Paul

--
Paul Smith
Center for Neighborhood Technology
Manager, Wireless Community Networks
Chicago IL, USA
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