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Date:      Wed, 3 Feb 1999 18:20:43 +1030
From:      Greg Lehey <grog@lemis.com>
To:        David Greenman <dg@root.com>
Cc:        Greg Black <gjb@comkey.com.au>, FreeBSD Questions <questions@FreeBSD.ORG>
Subject:   Re: Excessive collisions on Ethernet
Message-ID:  <19990203182043.D1179@freebie.lemis.com>
In-Reply-To: <199902011307.FAA02115@implode.root.com>; from David Greenman on Mon, Feb 01, 1999 at 05:06:59AM -0800
References:  <19990201123740.27312.qmail@alpha.comkey.com.au> <199902011307.FAA02115@implode.root.com>

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On Monday,  1 February 1999 at  5:06:59 -0800, David Greenman wrote:
>>> Well, the values for freebie are now:
>>>
>>> Name  Mtu   Network       Address            Ipkts Ierrs    Opkts Oerrs  Coll
>>> ed2   1500  <Link>      00.80.48.e6.a0.61 16493376    34 21501269     0 2326175
>>> ed2   1500  widecast      freebie         16493376    34 21501269     0 2326175
>>>
>>> Since yesterday, that's 8 million more output packets and 1.3 million
>>> collisions.  That suggests that something might be getting worse.
>>
>> Yes, it does look as though it's getting worse.  You may indeed
>> have a fault somewhere.  I'd certainly check the cables first,
>> and try swapping some of them around before pulling cards from
>> machines.  (I have to pull video cards from five machines
>> tomorrow to swap them for something that works with FreeBSD, so
>> I'm a bit jaundiced about pulling cards at the moment :-) )
>
>    Anything less than 50% collision rate is okay and doesn't reduce the
> throughput significantly. All of the numbers below are in the noise.

You mean it's the noise that's causing the collisions?

Seriously, it's clear that it's not affecting the performance, though
that surprises me; how long does a board hold off after a collision?
I haven't been able to find that info anywhere, but I once worked for
a nameless computer manufacturer whose net had about 50% collisions,
and the throughput was terrible.

The real question was: why is this happening?  I still suspect that
it's trying to tell me something, but I haven't a good feeling for
what.

Greg
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