Date: Wed, 03 Feb 1999 12:11:32 +0800 From: peter kok <peter@sweda.com.hk> To: Greg Black <gjb@comkey.com.au> Cc: Greg Lehey <grog@lemis.com>, FreeBSD Questions <questions@FreeBSD.ORG> Subject: Re: Excessive collisions on Ethernet Message-ID: <36B7CC74.5C09913B@sweda.com.hk> References: <19990131110224.I8473@freebie.lemis.com> <19990131192548.24006.qmail@alpha.comkey.com.au>
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Hello i would like to know how do you measure this collision? thank you Greg Black wrote: > > In the last few days I've noticed a really high number of collisions > > on my Ethernet. There are only 5 machines on the network, 3 of which > > are barely active, yet I see: > > > > (allegro, running 2.2.6-STABLE) > > ed0 1500 <Link> 00.00.c0.44.a5.68 43729816 45 43861788 12 977828 > > ed0 1500 widecast allegro 43729816 45 43861788 12 977828 > > That's only 1.1%. > > > (freebie, running 4.0-CURRENT) > > Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll > > ed2 1500 <Link> 00.80.48.e6.a0.61 11976144 12 13389307 0 988340 > > ed2 1500 widecast freebie 11976144 12 13389307 0 988340 > > And that's only 3.9% -- it's worse than allegro, but not by a > significant margin for the relatively small amount of traffic. > On my Ethernet, I have machines that report 0.01%, 9.6%, 0.7%, > 0.04% and 0.4%. The outlier is a machine that has been up a few > hours and was used for a large file transfer which blew its > average out of the water -- it'll be back to about 1% as time > goes by. > > > I tried an ftp from panic, copying a file of 45 MB from freebie. The > > transfer ran at about 1 MB/s with about 450 collisions per second on > > the freebie side, none on the panic side. Here are the values before > > and after: > > > > freebie: > > Ipkts Ierrs Opkts Oerrs Coll > > before 11978350 13 13392678 0 989089 > > after 11994616 13 13424921 0 1009912 > > diff 16266 0 32243 0 20823 > > > > panic: > > Ipkts Ierrs Opkts Oerrs Coll > > before 480 0 651 1 0 > > after 32143 0 16679 1 0 > > diff 31663 0 16028 0 0 > > > > Looking at these results (40% collision rate on freebie), it would > > seem that something is seriously wrong in the network. On the other > > hand, allegro also shows a large number of collisions. At the moment > > I'm suspecting the (3 month old) Ethernet board in freebie, but I was > > wondering if there were other reasons which might apply. > > I just did some 10 to 15 MB file transfers with NFS on my LAN (I > don't have FTP set up), and saw collision rates ranging from 25% > to 35% for those periods. I'd say that was pretty normal, given > the way that Ethernet works. The more interesting statistics > are the overall figures over time, and the ones you give at the > start aren't too bad. Yes, freebie is a bit high -- but 4% > compared with 1% is not a big factor, especially with the fairly > low total amount of traffic. I'd watch it for a bit longer > before deciding it was a real problem. After all, if you're > getting 1 MB/s on a 10 Mb/s LAN, you're doing pretty well :-) > > -- > Greg Black <gjb@acm.org> > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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