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

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