Date: Fri, 25 Jul 2003 11:48:22 -0700 From: Yuchung Cheng <ycheng@cs.ucsd.edu> To: freebsd-ipfw@freebsd.org Subject: Re: using dummynet to simulate modem, dsl, etc Message-ID: <20030725114822.A2287@cs.ucsd.edu> In-Reply-To: <20030725103814.A54554@xorpc.icir.org>; from rizzo@icir.org on Fri, Jul 25, 2003 at 10:38:14AM -0700 References: <3F212BF7.4060602@optusnet.com.au> <20030725103814.A54554@xorpc.icir.org>
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On 07-25-2003, Luigi Rizzo wrote: > I would expect you to get around 3.5KBytes/s in the steady state, > but with a packet transmission time of 200ms and the 600ms RTT of > your setting, the first few rounds might achieve somewhere between > that and twice the bandwidth because of less interference. > > This is exactly what you are seeing. > > Try this: > ipfw -q add 1 pipe 1 ip from any to 127.0.0.100 in > ipfw -q add 2 pipe 2 ip from 127.0.0.100 to any in > ipfw -q pipe 1 config bw 33kbit/s queue 0 delay 40ms > ipfw -q pipe 2 config bw 56kbit/s queue 0 delay 112ms > why set queue to 0? aren't modem banks usually 4K bytes? the reverse link has 3 times delay (c->s), is this for simulating ack spacing and busy server to client pipe? I am doing similar experiments. Anybody can share parameters for ADSL, cable modems too? Searching the web does not give any good information. Yu-chung
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