Re: Simulating client-side modems

From: cachemail@procache.com
Date: Sat Jan 13 2001 - 01:56:04 MST


Hi
 I checked the dummynet functionality, but I did not find any
 similar tool in Linux. Do you have any Idea(At the moment our
 environment is Linux)?

 There are structures such as pipe100Mbps and
 pipe56KbpsIn in polymix-2. Are they for future use?
 Is it possible to use them in this regard or not?

Vahid Fereydounkolahi
fereydunk@yahoo.com

On Tue, 9 Jan 2001, Alex Rousskov wrote:

> On Tue, 9 Jan 2001 cachemail@procache.com wrote:
>
> > Is it possible to simulate the modems actions in the client side?
> > I took a look at the Polymix-2 source. there are structures
> > such as NetPipe. But I do not know how can I use them is this regard.
>
> Yes, it is possible. We use DummyNet kernel feature of FreeBSD to
> simulate WAN delays. The same feature can be used to simulate modem
> clients or virtually any other network-related packet delays/loss/etc.
> Linux and other OSes have similar features/packages.
>
> You can look through PolyMix-2 description and the PolyMix-3 HOWTO
> document to get an idea how to use DummyNet.
> http://polygraph.ircache.net/Workloads/PolyMix-2/#WAN_Simulation
> http://www.measurement-factory.com/docs/PolyMix-3/
>
> The only big problem with using packet-level simulators is the
> performance overhead. However, if you do not need very high request
> rates or have many PCs, it should not be a big deal.
>
> Alex.
>
> P.S. PGL NetPipes are currently not used, but they were/will-be used
> for DummyNet-like configurations.
>



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