Linux has support for such 'fake' interfaces too. I know diald
(dial-on-demand-daemon) uses this for detecting and filtering traffic.
You might want to check the diald documentation and/or HOWTO for
details.
I would like to give more details myself, but unfortunately that's all I
know about this :(

Greets, Guy

Clemens Sibon wrote:
> 
> Hi there,
> >
> > Daniel Bergqvist (daniel@netatonce.se) wrote:
> > > How do you want the packets be dropped? What do you want to
> > > achieve? Which
> > > rules will control which packets get dropped?
> >
> > We have performed some measurements of packet drops on real
> > WAN link.  I
> > would like to reproduce the characteristics of (congested)
> > WAN link/router
> > as close as possible.  Rules for dropping will not be based on packet
> > contents but on a random variable with certain distribution
> > which in turn
> > depends on parametars such as packet size (e.g. for voice traffic).
> 
> I've been told that for FreeBSD (sorry :-) there is the dummynet-device,
> which has been specifically created to do such tests. Maybe this is
> off-topic but it could be what you're looking for!
> 
> Check http://info.iet.unipi.it/~luigi/ip_dummynet/ for details.
> 
> Greetings,
> 
> Clemens Sibon
> 
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