Date: Mon, 18 Dec 2006 08:27:59 +0200 From: Ian FREISLICH <if@hetzner.co.za> To: Looza <elias_nogueira@hotmail.com> Cc: freebsd-ipfw@freebsd.org Subject: Re: problem simulating a LFN Message-ID: <E1GwByh-0000mz-KP@hetzner.co.za> In-Reply-To: Message from Looza <elias_nogueira@hotmail.com> of "Sun, 17 Dec 2006 17:31:53 PST." <7922408.post@talk.nabble.com>
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Looza wrote: > > 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. Try sysctl net.inet.ip.fastforwarding=1 . With this set I can formard and filter in excess of 500kpps using less than 5% CPU on a Xeon. I highly recomend the Intel 82546GB chip based adaptors (em driver). Ian -- Ian Freislich
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