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Cisco Wireless Controller - all Wireless clients getting duplicate IP error.

Posted on 2012-04-13
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Last Modified: 2013-12-27
I have a Cisco 2504 Wireless Controller with one lightweight AP. The AP, WLC and wireless clients are all on the same subnet.

Every single wireless client gets a message that it has a duplicate IP address, even thought they don't. I even went as far as to assign a wireless client a static IP address that's not part of our DHPC leases and it gets a duplicate IP address error.

Any ideas?

I'm a novice when it comes to these and the person we paid to set it up doesn't have a clue.
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Question by:Jacob78
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Expert Comment

by:Anuroopsundd
ID: 37844224
do you have DHCP enabled on the AP and on LAN with same scope?
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Assisted Solution

by:Darr247
Darr247 earned 250 total points
ID: 37844711
Windows throws the duplicate IP error to every computer on the LAN, not just the one that has the duplicate IP.

Usually, static IP configuration causes duplicates far-more often than DHCP assignments.

Try runniing
arp -a
from a command window and see if that reveals which MAC addresses have the duplicate IP.

You can also check the System logs in start->run/search, eventvwr.msc [Enter]/click on each machine and see if it tells you what the duplicate IP was.
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Expert Comment

by:Darr247
ID: 37844754
> Usually, static IP configuration causes duplicates far-more often than DHCP assignments

It's not just in the main TCP/IP configuration where that static IP can be entered, by the way... check the Alternate Configuration tab, too.
And if there is a static IP assigned in TCP/IP properties, check in the Advanced button, also (extra IPs should be disabled there if DHCP is used, though).
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Author Comment

by:Jacob78
ID: 37844782
I checked the event viewer and even though I changed the static ip twice on this laptop, each time it's reporting the same mac address - 00:1E:4F:13:DE:39.

That MAC is a Windows 2003 server running dual broadcom NIC's setup with teaming. (It's the mac address of the 1st NIC and the mac of the team).

On a second WLAN laptop I checked the Event Viewer and this time it mentions 00:1E:4F:13:DE:3B - the second NIC on the same Dell Windows 2003 server above.

Now...when I disable the WLAN on the laptops and wire them to the network I don't get duplicate IP address errors.
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Accepted Solution

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Jacob78 earned 0 total points
ID: 37866266
The server mentioned above needed to have the BACS driver updated. Once it was updated, it ended our false duplicate IP errors.
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Author Closing Comment

by:Jacob78
ID: 37885306
I gave partial credit to Darr since it was his suggestion to run eventvwr.msc that lead me to find the final problem.
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