Subject: RE: [Ieprep] Summary of ieprep work and VoIP--Take 2

From: "King, Kimberly S." <[email-masked]>
Date: Tue, 17 Dec 2002 13:01:00 -0500

> On Tuesday, Dec 17, 2002, at 11:49 America/Montreal, King, 
> Kimberly S. 
> wrote:
> > For example, enough VoIP on a congested link (e.g., 10-40% 
> packet drop 
> > rates)
> > can be sufficient to make the link essentially unusable for TCP 
> > traffic.
> 
> I think that overstates the case. 

I'll be clearer.  From an offline conversation I had with Sally Floyd, 
she doesn't think TCP connections are going to be doing very well 
with 10-40% packet drop rates over a congested link.  She expressed
concern that without end-to-end congestion control for VoIP that
somewhere there is going to be a congested link and that VoIP
traffic will contribute significantly to that congestion resulting in 
a link completely unusable for TCP traffic.

I don't think I misunderstood and I hope I haven't
overstated but I've cc'd her just in case.

Kimberly
_______________________________________________
Ieprep mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/ieprep

---

From: RJ Atkinson <[email-masked]>
Date: Tue, 17 Dec 2002 13:51:33 -0500

On Tuesday, Dec 17, 2002, at 13:01 America/Montreal, King, Kimberly S. 
> a link completely unusable for TCP traffic.

We need to give Sally a chance to clarify, I think.

Things we seem to agree on:
- Letting non-congestion-avoiding traffic crowd out congestion-avoiding
   traffic is a very bad thing from an architectural or system 
engineering
   perspective.
- VoIP or any other application that doesn't include 
congestion-avoidance
   needs to be modified to implement and use congestion-avoidance.

We seem to disagree that the parameters you outline will result in "a 
link
completely unusable for TCP traffic".  In particular, my operational
experience says that 10+ % drop rates are annoying, but that TCP-based
applications (e.g. use of Telnet to read email over a 2.4 Kbps shared 
WAN
radio link) are still usable.  Now I'd prefer to have more bandwidth
in all cases, but there is a different between "completely unusable" and
"not as high performance as one might prefer".

Regards,

Ran
[email-masked]