dummynet and adsl

Francis GUDIN francis at u1030.c03.escapebox.net
Thu Mar 18 08:36:30 PST 2004


On Thursday, 18 March 2004 at  8:08:49 -0800, Luigi Rizzo wrote :
> 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
> 

Thank you ! Things are much clearer to me, now. Back to work !

BR,
Francis.


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