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<TITLE>RE: creating controlled latency/jitter</TITLE>
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<P><FONT SIZE=2>Gerald Combs wrote:</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> crash3m wrote:</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> > I need to test some real time traffic, but I need to create some </FONT>
<BR><FONT SIZE=2>> > 'interference' to simulate a flaky internet connection. I am trying </FONT>
<BR><FONT SIZE=2>> > to create controlled latency so that I can determine at which point </FONT>
<BR><FONT SIZE=2>> > latency (and jitter) becomes a big problem. Would this be a job for </FONT>
<BR><FONT SIZE=2>> > QoS?</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> If you need to simulate flakiness at layer 2 you might be able to use</FONT>
<BR><FONT SIZE=2>> FreeBSD's dummynet(4) driver. Dunno if there's an equivalent Netfilter</FONT>
<BR><FONT SIZE=2>> module for Linux.</FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2>We've used dummynet here at work. It works well. You can control bandwidth, latency, packet loss, multiple paths...</FONT>
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<P><FONT SIZE=2>Here's a short tutorial:</FONT>
<BR><FONT SIZE=2><A HREF="http://cs.ecs.baylor.edu/~donahoo/tools/dummy/tutorial.htm" TARGET="_blank">http://cs.ecs.baylor.edu/~donahoo/tools/dummy/tutorial.htm</A></FONT>
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<P><FONT SIZE=2>And it's author's page:</FONT>
<BR><FONT SIZE=2><A HREF="http://info.iet.unipi.it/~luigi/ip_dummynet/" TARGET="_blank">http://info.iet.unipi.it/~luigi/ip_dummynet/</A></FONT>
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<P><FONT SIZE=2>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.</FONT></P>
<P><FONT SIZE=2>cheers,</FONT>
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<P><FONT SIZE=2>Garrett</FONT>
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<P><FONT SIZE=2>--</FONT>
<BR><FONT SIZE=2>Garrett Goebel</FONT>
<BR><FONT SIZE=2>IS Development Specialist</FONT>
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<P><FONT SIZE=2>ScriptPro Direct: 913.403.5261</FONT>
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<BR><FONT SIZE=2>www.scriptpro.com garrett at scriptpro dot com</FONT>
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