Date: Sun, 16 Mar 2003 15:37:50 -0500 From: Bill Moran <wmoran@potentialtech.com> To: Olivier Dony <odony@student.info.ucl.ac.be> Cc: Simon Barner <barner@in.tum.de>, freebsd-questions@freebsd.org Subject: Re: Too many collisions on network? Message-ID: <3E74E09E.8050203@potentialtech.com> In-Reply-To: <025601c2ebf5$5abc25f0$1502a8c0@blacktrap.net> References: <005d01c2ebcb$82b343b0$1502a8c0@blacktrap.net> <20030316152335.GA1434@zi025.glhnet.mhn.de> <002201c2ebd3$92d0a7d0$1502a8c0@blacktrap.net> <3E74B8BC.4030009@potentialtech.com> <025601c2ebf5$5abc25f0$1502a8c0@blacktrap.net>
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Olivier Dony wrote: > On Sunday, 16 March, 2003 18:47, Bill Moran wrote: >>Going to full-duplex should reduce collisions to 0, and give you the max >>performance available. I just did some experimenting with turning duplex >>from half to full and back on my computer here, and if there's any interruption, >>it was less than I could easily measure. Don't know if that'll be the same >>with all switches or not. > > Well after doing some poking around on other servers first, I did change the > mode and happily that didn't interrupt the connection. Also the collisions > did drop to 0 on all 3 servers where I tried it, with a small difference : > o On the other 2 servers I changed from autoselect 10BaseT/UTP h-d > (resp. 100BaseTX/UTP) to 10BaseT/UTP full-duplex (resp. 100BaseTX/UTP f-d), > and collisions dropped to 0, nothing else seems to have changed, still no > i/o errors, and no change in the bytes throughput. > o On the server I was talking about earlier, here is an excerpt of netstat > while switching from half to full-duplex and back : > > input (Total) output > packets errs bytes packets errs bytes colls > 900 0 141953 1261 0 1351094 633 > 938 0 163593 1048 0 1157276 543 > 782 0 126538 938 0 1090243 414 > 771 0 124376 987 0 1217638 493 > 894 0 161036 1059 0 1111060 573 > 913 0 123942 1092 0 1028476 562 > -> going full-duplex... here I guess > 601 11 72155 695 0 569992 132 > 461 8 61467 566 0 560226 0 > 462 12 61552 546 0 649187 0 > 477 6 72589 555 0 649629 0 > 517 13 79602 624 0 668592 0 > -> back to half-duplex with autoselect .. looks like here > 0 0 42814 0 0 500765 0 > 815 0 150286 1128 0 1841082 749 > 1062 0 176522 1478 0 2051510 554 > > The input errors and other numbers were consistent during the few minutes of > testing in all 3 cases, but I cut it to a few lines for the sake of the > mailing-list. Is this increase in input errors and drop in bytes throughput a > problem? I guess the input errors are not good, when we can see that there are > no real erroneous packets coming in before. As for the change in throughput > while the server load stayed constant, it doesn't look good either, and I didn't > notice the same behaviour on the 2 others. Those don't have the same load though. > > Any ideas? And thanks again, I've learned a lot so far with your kind help :-) Off the top of my head I would worry about wiring faults, or a switch with a bad port, or possibly a buggy NIC. Collisions are normal on half-duplex networks, and errors are normal on all networks, but not at the levels you're reporting. I can't think of where else to look but a hardware issue at this point, but I could be wrong. -- Bill Moran Potential Technologies http://www.potentialtech.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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