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 From:  Chris Buechler <cbuechler at gmail dot com>
 To:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] Re:Re: [m0n0wall] Collisions on WAN Interface
 Date:  Sun, 19 Dec 2004 15:50:05 -0500
On Sun, 19 Dec 2004 18:32:06 +0100, Frederick Page
<fpage at thebetteros dot oche dot de> wrote:
> >Overall it is working like a charm, fast, no problems.
> Same here, I cannot really complain. Yet the collisions worry me,
> that's needless (IMHO).
> >I was only wondering if that "much" collisions are normal or if this
> >is problem.
> From my point of view: it seems to be "normal", although I do not like
> this.

When you're stuck using half duplex between devices, you're going to
get collisions.  How many depends on a lot of things, but a heavily
loaded link will do that more than under light load.  You never see
collisions on your full duplex links because it's impossible.

Hard to say what is to be expected and what is excessive.  I just
checked one of my firewalls (Cisco PIX) that's hooked to its perimeter
router via 10 BT half duplex because the ISP forces it to that, and
it's showing a bit under 2% collisions.

The cable and DSL modems I have connected to m0n0wall are all 100BT
full duplex, so I never see any collisions there.  I've seen
misconfigured setups where one side was half duplex and the other full
and you end up with 15-25+% collisions.

I have seen a couple of those Speedstream 5800 series SDSL modems,
though I promptly ripped them out and replaced the SDSL (typically 256
or 384 Kb) with business class 3.0/384 ADSL that's cheaper and comes
with a DSL modem that'll do 100BT full duplex.  :)  Those Speedstreams
are 10BT half duplex, so you're going to be stuck with collisions on
those.  Sounds like it's negotiating properly, so leave well enough

Double check that the duplex between the devices isn't mismatched,
other than that, I wouldn't worry about it.  If that number wasn't
there, you wouldn't think anything of it.  :)  Back in the day when
networks were 10BT hubs, when you had a network with moderate traffic,
the collision light on the hubs would be on almost constantly.