dummynet and modem pipes

[Shawn Barnhart]

----- Original Message ----- 
From: "Yuchung Cheng" <ycheng at cs.ucsd.edu>
To: <ipfw at freebsd.org>
Sent: Friday, September 05, 2003 11:50
Subject: dummynet and modem pipes


> when simulating modem pipes using dummynet, how do we simulate the
> modem compressions? one way is to pick a compress rate, say 2, and setup
> fake larger bandwidth, but do different traffic (html, jpg, mpg) affect
> the compression latency or compression rate significantly? tia

Our Cisco RAS equipment usuall reports an "efficiency improvement factor" of
1.2, which I presume means a compression rate of about 20%.

I'd say give it 10% more bandwidth and call it a day, since a fair amount of
info will be precompressed and uncompressable.