Date: Wed, 3 Feb 1999 18:16:04 +1030 From: Greg Lehey <grog@lemis.com> To: Robert Clark <Clark@open.org> Cc: peter kok <peter@sweda.com.hk>, Greg Black <gjb@comkey.com.au>, FreeBSD Questions <questions@FreeBSD.ORG> Subject: Re: Excessive collisions on Ethernet Message-ID: <19990203181604.B1179@freebie.lemis.com> In-Reply-To: <3.0.6.32.19990202225702.0089e840@opengovt.open.org>; from Robert Clark on Tue, Feb 02, 1999 at 10:57:02PM -0800 References: <36B7CC74.5C09913B@sweda.com.hk> <19990131110224.I8473@freebie.lemis.com> <19990131192548.24006.qmail@alpha.comkey.com.au> <36B7CC74.5C09913B@sweda.com.hk> <19990203144110.W1179@freebie.lemis.com> <3.0.6.32.19990202225702.0089e840@opengovt.open.org>
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[Format recovered at freebie.lemis.com] On Tuesday, 2 February 1999 at 22:57:02 -0800, Robert Clark wrote: > At 02:41 PM 2/3/99 +1030, Greg Lehey wrote: >> On Wednesday, 3 February 1999 at 12:11:32 +0800, peter kok wrote: >>> 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%. >>> >>> i would like to know how do you measure this collision? >> >> This is output from netstat -bi: >> >> $ netstat -bi >> Name Mtu Network Address Ipkts Ierrs Ibytes Opkts Oerrs Obytes Coll >> ed2 1500 <Link> 00.80.48.e6.a0.61 358053 5 64720004 458435 0 320307968 8347 >> ed2 1500 widecast freebie 358053 5 64720004 458435 0 320307968 8347 >> >> BTW, I had to reboot freebie. Since then, the incidence of collisions >> is *much* lower. There's something funny going on here. > > I've seen weirdness like this before, but I can't bring the > cause to the front of my brain at the moment. > I seem to remember one case where a 10-base-T cable had the > wrong polarity on the rx pair, and this was causing a station to > miss its collision sense. Consequently it wasn't doing a good job > of backing off early. > > Before anyone gets grumpy with me, I may have the details of > the cable fault wrong. I also remeber a case where one wire of the > rx pair was marginal, and the system functioned, albeit > irrationally. > > At least once a year I run into someone using two 10-base-T > nics on the same hub port. How? Some hubs have a port that is both a > "regular" and "uplink" port. When two station are connected this > way, the tx collisions slip in under the collison sense > mechanism. It can be quite a good laugh when you try to explain why > not to use both ports at once. ( I haven't seen a lan analyzer yet > that will pinpoint this specific problem. ) Interesting. That's not the case here, because the whole network is RG 58. > zzzzzz... oops, I'm curious to see what it turns out to be. I suspect hardware failure, software bug (it only happens with the ed driver; other Ethernet boards are unaffected) or phase of the moon. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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