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Date: Thu, 18 Mar 2004 08:08:49 -0800
From: Luigi Rizzo <rizzo@icir.org>
To: Francis GUDIN <francis@u1030.c03.escapebox.net>
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References: <20040318105728.GA2470@u1030.c03.escapebox.net>
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In-Reply-To: <20040318105728.GA2470@u1030.c03.escapebox.net>;
	from francis@u1030.c03.escapebox.net on Thu, Mar 18, 2004 at 11:57:28AM +0100
cc: freebsd-ipfw@freebsd.org
cc: freebsd-questions@freebsd.org
Subject: Re: dummynet and adsl
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On Thu, Mar 18, 2004 at 11:57:28AM +0100, Francis GUDIN wrote:
> Hello everybody,
> 
> I'm in the process of setting up a bandwidth control with ipfw and
> dummynet. My connection is done through pppoe on adsl.
> 
> In ipfw(8), i found the following:
>  "If a device name is specified instead of a numeric value, as in
> 
>        ipfw pipe 1 config bw tun0
> 
>   then the transmit clock is supplied by the specified device.  At
>   the moment only the tun(4) device supports this functionality,
>   for use in conjunction with ppp(8)."
> 
> Having two different bandwidth available (up- and downstream), would
> this option work ? Or, is only symetric bw case taken into account

'bw tun0' means that the pipe will transmit a new packet when
the device's (tun0 in this case) transmit queue becomes empty.

In any case the question is irrelevant here because tun0's queue
is drained by the userland process reading from /dev/tun0
and writing onto the output link. With a serial line and no
buffering you could hope that this matches the outbound
bandwidth, but with pppoe on adsl you basically see the
ethernet speed on transmission.

	cheers
	luigi