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Date:      Fri, 5 Sep 2003 15:14:19 -0500
From:      "Shawn Barnhart" <swb@grasslake.net>
To:        "Yuchung Cheng" <ycheng@cs.ucsd.edu>, <ipfw@freebsd.org>
Subject:   Re: dummynet and modem pipes
Message-ID:  <0cfe01c373ea$4a386fe0$62229fc0@ad.campbellmithun.com>
References:  <20030905095038.D28924@cs.ucsd.edu>

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----- Original Message ----- 
From: "Yuchung Cheng" <ycheng@cs.ucsd.edu>
To: <ipfw@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.



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