[TriLUG] Wierd Network Problem - Clues Appreciated

[jonc at nc.rr.com]

This behavior is indicative of attempting to use the cross-over port as
both your hub connection and as a PC connection.  On LinkSYS router (and
others) their is a single port that has two connectors associated with it -
one of the connectors has the wires crossed and is used for hooking up with
a hub, the other connector is simply straight through and is for use if you
are hooking up a computer. If you use one connector, you are not supposed
to use the other (as both hook to the same port).

HTH - Jon Carnes (from the road)

Original Message:
-----------------
From: Jason Tower jason at cerient.net
Date: Tue, 26 Nov 2002 11:06:59 -0500
To: trilug at trilug.org
Subject: Re: [TriLUG] Wierd Network Problem - Clues Appreciated


try this:

plug everything into a hub (not a switch) and use ethereal on one of the
good 
machines to record all traffic to/from the bad machine.  maybe analyzing
the 
results can point you in the right direction.

if you don't live far from raleigh, i'd be happy to give you a hand (i 
genuinely enjoy finding/fixing network problems).  i have a spare router
box 
that we can try as well to see if that's the root cause.

jason

On Tuesday 26 November 2002 10:57, Scott Chilcote wrote:
> Hi Folks,
>
> One of the systems on my LAN started dropping packets really bad when I
> tried communicating with machines out on the internet.  Pinging sites
> like yahoo and ibiblio would return 3 out of 7,  2 out of 10, etc. and
> TCP connections (email, web) just timed out.
>
> I tried two other machines on the same LAN, and they had no problems
> communicating with systems on the internet.  This seemed to rule out the
> broadband router and DSL modem.
>
> The next thing I tried was replacing the NIC and the ethernet cable on
> the problem machine.  This turned out to make no improvement.  Then it
> occurred to me to try pinging other systems on the LAN with this one,
> and that worked just fine.  I put the old NIC back in, and it still
> worked fine.  It's only getting out to the internet with this system
> that isn't working.  I even tried it with a webserver running on a local
> system, and the web page came up fine.
>
> I then started wondering if there was a problem with one of the ethernet
> connections on the DSL/Router/Switch or one of the other switches, so I
> tried changing those around.  This made no difference.
>
> I've more or less ruled out an OS or configuration problem on this
> machine, too.  It's a dual-boot system with Win98se on one partition.
> The behavior is identical under Win98se.  There have been no recent
> configuration changes to this system other than adding a USB connected
> UPS.  I haven't tried removing that, but I guess it's worth doing.
>
> Another symptom happens when I try to bring up the SMC DSL Router's
> administration web page.  The other systems can bring this page up
> instantly.  The "problem" system takes forever to bring it up, and it
> draws in a tiny piece at a time.  It did this even after I swapped out
> the NIC and the ethernet cable.  This happens even though pings sent to
> this LAN address return just fine.  This sort of indicates a TCP problem.
>
> Has anyone seen this kind of behavior, or can you suggest something else
> to try?  I'm guessing there's something wierd going on inside the
> hardware of the faulty system, or there's a bizarre problem with the DSL
> router that makes it single out this one machine.  I hate to blow $100
> on a replacement DSL router if it isn't actually bad.
>
> Thanks for any help!
>
>                             Scott C.
>
>
>
>
>
>
>
>
>
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