[TriLUG] Wierd Network Problem - Clues Appreciated

[Chris Hedemark]

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If things on your local network segment are working fine with this 
machine, but not out on the Internet (or other segments), I might 
suspect a problem with the MTU size.

On Tuesday, November 26, 2002, at 10:57 AM, 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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>
>

Chris Hedemark
Hillsborough, NC
http://yonderway.com


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