Date: Sun, 17 Dec 2006 17:31:53 -0800 (PST) From: Looza <elias_nogueira@hotmail.com> To: freebsd-ipfw@freebsd.org Subject: problem simulating a LFN Message-ID: <7922408.post@talk.nabble.com>
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Hi, I'm trying to simulate a LFN(Long Fat Network) to test various TCP versions. I am using iperf on the end PCs. I'm trying to use FreeBSD's ipfw to simulate a LFN. ex. throughput=1 Gbit/s and delay=100ms, trhoughput=100 Mbit/s and delay=1s This is how my hardware is connected. |Linux PC|--Gigabit--| FreeBSD box |--Gigabit--|Linux PC| With this configuration: >ipfw 500 add allow ip from any to any I get speeds of about 200 to 300 Mbit/s and the CPU usage goes up to 99%. I've googled this problem and it seems that some good quality NIC do most of the processing so that the CPU doesn't have to. Unfortunately I have bad quality NICs so the CPU does all the processing, stoping the throughput at these speeds. With this configuration: >ipfw 100 pipe 1 add ip from 192.168.0.1 to 192.168.1.1 >ipfw 500 add allow ip from any to any >ipfw pipe 1 config delay 100ms I get speed of just 10 Mbit/s. I've do some testing and increasing the delay will lower the troughput, decreasing th delay will boost the throughput. I've tested the queue and the bw option and it seems it makes no difference. PIng will show 200ms RTT(Round Trip Time) wich is what I'd expect except for the troughput. My first question is if anyone knows off some way to get the processing out of the CPU so that I can achieve gigabit speeds without ? My sencond question is if there is a way of setting the ipfw delay option so that it does not alter the troughput? PS - I hope I can be understood. -- View this message in context: http://www.nabble.com/problem-simulating-a-LFN-tf2837638.html#a7922408 Sent from the freebsd-ipfw mailing list archive at Nabble.com.
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