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Users losing connection to network...

Last response: in Networking
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August 24, 2005 9:06:11 PM

For the past few days, we have been having a problem where users are losing connection to network resources, as often as every 15 minutes on some computer and sometimes only once or twice a day on others. It is consistantly the same PCs that stay up for longer periods and conistant to those which keep going down every 15 minutes or so.

When a computer is in this state, they are unable to ping other computers, cannot be pinged by other computers, and are unable to access network resources (namely their mapped drives).

If we do an IPCONFIG /release then IPCONFIG /renew, they can be pinged and once again access all network resources. We are using a domain and managing users in Active Directory.

This problem started happening on Friday morning last week. I did rollback some patches I had done to the server after this began happening, but that didn't seem to help. No other major changes were made to the network.

All our computers come into one of two switches that are linked together. Our one server (Windows 2000) is also connected to this setup. I have swapped out both switches and this has not solved the problem. None of these switches are managed.

I recently added a Cisco switch that was a backup for one of our offsite systems. I added two computers on this switch (which is linked to the other two). Neither had problems for many hours. Then I added a third user and all three began having problems. So I removed this third users, but the two remaining are still having issues.

When you ping a computer from the Cisco router, you always get a reply. This seems to "wake up" computers that previously weren't working and they suddenly regain asscess to network drives and can ping/be pinged.

Does anyone have any ideas? I have been working on this for the past three days and am running pretty dry on things to try. I have tried static IPs, which result in the same problem, and it does not seem to matter which switch the users or server is on. I have ran virus scans and Adaware on all PCs and didn't find anything. I have checked for updates on a few and updated network drivers, but that hasn't helped either.

I am thinking there could be something wrong with one of the user's computers that is affect the network, but none of the lights on the switches appear to indicate anything out of the ordinary.

By the way, most of our computers are Windows XP Pro and there are a few 98s. Both seem to experience the same problem.<P ID="edit"><FONT SIZE=-1><EM>Edited by kriswd40 on 08/24/05 05:09 PM.</EM></FONT></P>
Anonymous
August 25, 2005 1:42:43 PM

Have you tryed netstat -a (also -o on XP). Its gonan show all the network connection, maybed computer are getting "sturated" you should investigate this a bit.

Also you should monitor traffic on the switch, maybe there is some sort of overload. Some ports on the switch might be defective too, you should investigate that.

Just as an example, some conmputer on the same story would loose conenctivity when I was running a Multicast Ghosting session. It seamed to saturate the network...

So I would think the problem lies in some sort of traffic congestion, maybe some equipement stock in a loop or something, making lots of chatter on the network!

Asus P4P800DX, P4C 2.6ghz@3.25ghz, 2X512 OCZ PC4000 3-4-4-8, MSI 6800Ultra stock, 2X30gig Raid0
August 25, 2005 2:39:34 PM

I ran that netstat tool and didn't see any computer connections that shouldn't be there. I did notice a lot of TCP ports on the server that were listening, I have no idea how many is normal though.

We haven't noticed any unussual network traffic, but only one of our switches has an interface that you can monitor this with. I have been relayed this information since the switch is a Cisco 2900 and I just started here a few weeks ago and am not familiar with the commands for Cisco equiptment... if anyone knows a few things to do on a Cisco switch to monitor my traffic, that would be great. I have been unable to locate any documenation for this particular switch.


<P ID="edit"><FONT SIZE=-1><EM>Edited by kriswd40 on 08/25/05 10:40 AM.</EM></FONT></P>
Anonymous
August 25, 2005 4:11:50 PM

With cisco switch, you mainyl have to use DEBUG command so it shows you stuff...

The best way to monitor is thru SNMP protocol. I recently setuped a program called MRTG that graphs bandwith/cpu/meme usage thru snmp...It not a easy .exe click setup and you might not have the time for that but you can give it a shot if you like.

Maybe riser will have a few ideas...

Asus P4P800DX, P4C 2.6ghz@3.25ghz, 2X512 OCZ PC4000 3-4-4-8, MSI 6800Ultra stock, 2X30gig Raid0
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