*BSD News Article 83359


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From: Ken Bigelow <kbigelow@www.play-hookey.com>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Network Links won't light...
Date: Tue, 19 Nov 1996 19:39:04 +0000
Organization: Erol's Internet Services
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Message-ID: <32920CD8.189F@www.play-hookey.com>
References: <3291FC3E.1A89@mail.csra.net>
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Sam Brown wrote:
> 
> I've installed FreeBSD on yet another system and am running into a
> problem: my Network cards show no sign of operation.  Nada.  Zilch.  The
> link light doesn't even come on.  I've ruled out the idiot problems
> (yes, they're plugged in, yes, the right kind of cable) on a physical
> level, and have recompiled the kernel (since i couldn't find evidence
> of  a de0 probe anywhere in my boot sequence... the card i am using
> would look for that...) ...
>         Thoughts?
>                 S.

Sounds like a termination problem. You don't specify, but I assume
you're using thinnet Ethernet here. If that is the case, turn off all
boxes on the net and then measure the resistance between the center
conductor and the shield at any T-connector to any netcard. You should
measure very close to 25 ohms (two 50-ohm terminators, one at each end).
If you measure zero ohms, the cable is shorted somewhere. 50 ohms means
one terminator is missing or loose. Infinite resistance means neither
terminator is connected or the cable itself is open. Any of these wrong
measurements means that the network is down until it is fixed.

If it is a cable problem, check first the connectors at the new box you
just installed.

If you're using RJ45 connectors to a hub, the problem is a bit trickier
to find, but is likely to be similar. Again, start with your
newly-installed machine.
-- 
Ken

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