LAN wiring infrastructure

[stergiosnik]

Hello All.

I have a strange problem in a computer lab.

I switch on a Windows XP PC.
I try to logon but I can not.
I logon as local administrator and I notice that the netcard although it is enabled it is not functioning.
I check the netcard's led from behind and I see that it is off.
I switch off the PC and unplug the power cable from power supply for 2 minutes and I replug it.
I switch it on. I notice that netcard's led is on and I can logon.

This symptom occured on 5 PCs. After 2 days the same symptom occured on another 8 PCs in the same lab but these PCs are not the same but different. So the problem seems to occur randomly on random PCs.

I figured out that the Lan Wiring infrasture has a problem in the lab. On the floor there are plastic channels and inside I noticed that the infrastructure power cables are touching on the utp cables. Can this cause network singal inteference?

What is causing the problem on the netcard?
Is it the lan wiring infrastructure problem?
Is it the network layer 2 switch?
Is it the PCs power supply that must be replaced?

Thank you in advance.

Stergios

 

[promisek2]

what name brand of swicth are u using and which Cat of utp are u using

 

[IPKONFIG]

Interference or EMI from power cords to UTP cabling will not cause NIC cards to just quit working. You have a hub/switch issue.

"I can picture a world without war. A world without hate. A world without fear. And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

 

[stergiosnik]

The PCs that are having this netcard symptom are connected on a 3com switch. I do not know the utp category type. The only thing that I noticed is that the infrastructure power cables are touching on utp cables inside the same plastic channel on the floor.

The last few days I noticed another symptom on another PC in the same lab which is connected on different switch. The PC takes ages to logon. If I shut it down and unplug power from begind for 2 minutes then the PC loads normally fast. I tried to logon again after 2 hours and the same sympom occured.

Any ideas?

 

[IPKONFIG]

Your symptoms would indicate a spanning tree problem to me. Do you only have one connection from that 3 com switch to another switch somewhere else?

"I can picture a world without war. A world without hate. A world without fear. And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

 

[technome]

Agree with IPconfig quality Ethernet cable is highly resistant to EMI.
At one site had ship welders using very high current, welding 6" from an Ethernet bundle (on other side of a plaster wall). The monitor were picking up the EMI, totally unreadable at times, but the network had no issues.
When was the last time the Ethernet cables/patch cords certified ?
"What is causing the problem on the netcard?"
Extremely rare a network card goes bottom up, 95% of the time it the Ethernet cable/patch cord.


........................................
Chernobyl disaster..a must see pictorial

http://www.kiddofspeed.com/default.htm

 

[stergiosnik]

The Windows 2003 servers are connected on a main switch. Some lab PCs are connected to the 3com switch which uplinks to main switch and some other PCs connect to another switch which uplinks to main, too. The switch connectivity is quite simple. Also, the switches are simple unmanaged.

 

[VinceWhirlwind]

Make sure spanning-tree portfast/rapid spanning-tree is enabled on the PC switch ports.

 

[stergiosnik]

The problem the last week did not occur again. I was checking the lab PCs daily. Suddently disappeared. This Spanning Tree problem occurs always or is triggered by something?

Stergios.

 

[VinceWhirlwind]

You need to get onto the switch when this happebns and do a "show interface..." for the interface which has gone down to see what it says.
You should zero the port statistics counters first.