creating controlled latency/jitter

[Garrett Goebel]

Gerald Combs wrote:
> 
> crash3m wrote:
> 
> > I need to test some real time traffic, but I need to create some 
> > 'interference' to simulate a flaky internet connection.  I am trying 
> > to create controlled latency so that I can determine at which point 
> > latency (and jitter) becomes a big problem.  Would this be a job for 
> > QoS?
> 
> If you need to simulate flakiness at layer 2 you might be able to use
> FreeBSD's dummynet(4) driver.  Dunno if there's an equivalent Netfilter
> module for Linux.
 
We've used dummynet here at work. It works well. You can control bandwidth,
latency, packet loss, multiple paths...

Here's a short tutorial:
http://cs.ecs.baylor.edu/~donahoo/tools/dummy/tutorial.htm

And it's author's page:
http://info.iet.unipi.it/~luigi/ip_dummynet/


I spent a long time looking for an equivalent linux solution. There used to
be something that could be made to introduce latency using ethertap and a
2.2 kernel. But I was otherwise unable to find a way to simulate delay using
linux. If anyone knows of anything, please let me know.

cheers,

Garrett

--
Garrett Goebel
IS Development Specialist

ScriptPro                   Direct: 913.403.5261
5828 Reeds Road               Main: 913.384.1008
Mission, KS 66202              Fax: 913.384.2180
www.scriptpro.com          garrett at scriptpro dot com
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