Date: Tue, 30 May 2006 16:02:28 -0400 From: Mike Meyer <mwm-keyword-freebsdhackers2.e313df@mired.org> To: hackers@freebsd.org Subject: Asymmetric ethernet throughput? Message-ID: <17532.42196.508218.964130@bhuda.mired.org>
next in thread | raw e-mail | index | archive | help
I was doing some network testing, and noticed something odd: The network throughput was asymmetric. I was sending between 2 and 5 times as much data as I was receiving. Swapping the ends of the test didn't change that. Changing the non-FBSD box for a FBSD box made the throughput symmetric. Details: One end is always a FreeBSD 5.5 box with a RealTek 8138 nic. Testing is done with netstrain, built from ports. I first saw this with an OSX 10.4.6 box, a G4 powerbook. The FreeBSD box was sending ~10MB/sec on a 100BaseT network, which I regard as excellent. But I was only receiving 3M/sec. I tried swapping the server and client ends of netstrain, and got the same results: I was sending 10MB/sec to OSX, and receiving about 3MB/sec from it. I then tried making the other end a FBSD 6.1-RELEASE box, and the throughput was symmetric, with both ends sending and receiving 10MB/sec. I rebooted the 6.1 box into Ubuntu lunix running a 2.6.12 kernel. Again, I got asymmetric results - but this time it was the other way: I was receving ~10MB/sec, but only sending about 3MB/sec. Trying this between the Linux box and the OSX box (sorry, I've only got one of each) gave me symmetric ~10MB/sec throughput. I'm just curious if there's an explanation for this. Thanks, <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/consulting.html Independent Network/Unix/Perforce consultant, email for more information.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?17532.42196.508218.964130>