Ok, here’s one that has me banging my head against a wall.
The players:
1.) The client: A relatively new (< 6 months) Dell Optiplex GX100 with an integrated 3Com 3C920-TX NIC. Running Win98 SE, with the latest 3Com drivers.
2.) The switch: A new3Com EtherFast 10/100 Switch. Has about 10 other users on it, no one else is having problems.
3.) The connection: A short copper run to an Allied Telesyn media converter. Then fiber optic to another converter, and copper to the switch.
The problem:
Starting about 2 weeks ago, the client's network connection would randomly drop. The user stated then that if he rebooted, it almost always came back on. The user also mentioned that it happens up to 10x a day, and that it seemed to happen most often when he left his PC for about 20 minutes or so. He has since backed away from the last statement.
Upon further investigation, I've witnessed the event. When the connection goes down, I could not get it back by rebooting the PC, nor was the PC left alone for any amount of time. The NIC LEDs were off, as were the Link LEDs on the media converters. Now, here's the odd part. I hooked a 3Com hub up on his desk, while everything was showing no link. The hub linked up, as did his NIC to the hub! After removing the hub, we were back to no link. After toying with the media converters a bit, they linked back up. It may have been a coincidence, but toggling the Normal/Link Test button seems to have done the trick.
The Steps taken so far:
1. Replacing the NIC with a new 3Com 3C905C-TX and changing switch ports
2. Adjusting all power management settings to disabled.
3. Hard setting the media converters and NIC to 100 half-duplex
4. Having the fiber optic installer clean and re-terminate the lines
So, does anybody have any ideas? I'm trying to get the fiber installer to replace the media converters, but am really not so sure that that's where the problem lies.....
