Possible ARP Problem

[prior_tim]

Hi All

 

Im having a strange problem. Im running a network with around 200 computers running windows 7. My Domain Controller and DHCP Server are windows 2008 R2.

 

I have 5 computers suffering from the same problem. They have an IP Address from the DHCP server but they are unable to communicate with the rest of the next work. I am unable to ping the domain controller from these computers. Other computers are fine. This seemed to happen last Friday afternoon, before then they were all fine.

 

If I plug another computer into the same network socket as one of the problem PCs it works fine. If I take the problem PCs and plug them into another location on the network they start to work. Once I plug them back into the original network socket then the problem persists.

 

If I add an additional Network Card to the problem PCs disabling the Onboard one that fixes the problem. Also if I reformat the Hard Drives and Reinstall Windows that also fixes the problem.

 

My only clue to what is going on is when I pxe boot to my WDS server instead of getting an IP Address from the DHCP server I get an ARP Timeout error.

 

Any one have any ideas.

 

Many thanks for any help.

 

Tim

[pow]

Have you restarted the switch that the computer is attached to?

[FN-GM]

It might be worth checking to see if the MAC addresses are unique. Had similar before when the MAC addresses on the devices where the same!

[prior_tim]

Hi

Thanks for those. Ive fixed the problem by replacing two old 100mb switches with 1000mb ones. Not sure why both of them started to have the problem at the same time. But they were over 10 years old and both the same model.