Date: Tue, 01 Jun 1999 15:03:48 -0600 From: Wes Peters <wes@softweyr.com> To: Dennis <dennis@etinc.com> Cc: Jason Thorpe <thorpej@nas.nasa.gov>, hackers@FreeBSD.ORG Subject: Re: xl driver for 3Com Message-ID: <37544AB4.C65E5DB8@softweyr.com> References: <199906011650.MAA24039@etinc.com>
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Dennis wrote:
>
> At 08:00 AM 6/1/99 -0700, you wrote:
> >On Tue, 1 Jun 1999 10:09:59 +0200
> > Alexander Maret <maret@axis.de> wrote:
> >
> > > At first I tried my FreeBSD machine and I got about 800-900 collisions.
> > > Second I booted on the same machine linux and I only got 4 (!) collisions.
> >
> >It's also possible that Linux isn't counting the collisions properly.
> >
> > > I have no problem with thousands or millions of collissions, as long as
> > > they don't crash my computer. I just want a running system.
> >
> >Collisions don't cause your system to crash. If this is happening,
> >something else is at fault (though that something else may be an
> >unrelated problem in the Ethernet driver).
>
> If your nic driver chains packets (such that there is no time in between)
> you will see good throughput from the box but your overall network
> performance will suffer.
Overall network performance will be much greater until the collision rate
raises high enough to lower it. The only way to determine this is to
try it, unless you have some pretty sophisticated network modelling tools.
> A PCI card with continueous traffic can completely
> hog your lan (particularly at 10Mb/s)...
Even at 100Mb/s with good cards and moderatly fast computers. "Hogging
your LAN" is spelled the same as "getting 100% throughput" around here,
and is considered a GOOD thing. I fail to see how obtaining 200Mb/s
(full-duplex) throughput on a $50 lan adapter is a bad thing.
> which can cause a lot more
> collisions on your network as other devices will not have access until the
> hog is finished sending. For "Fairness" gaps in between frames are better
> as you approach capacity of your wire.
Or just do yourself a favor and buy a good switch, which avoids the
collision problems neatly. Ethernet doesn't have to be a shared media
system. I can help if you want suggestions. ;^)
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
http://www.softweyr.com/~softweyr wes@softweyr.com
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