WLC IP Conflict with AP-Manager Interface

Unanswered Question
Mar 10th, 2010

I am getting an error log in the WLC saying, its IP address is being used by another machine with MAC address A.B.C.D

But this MAC address A.B.C.D is the MAC address of the AP-Manager Interface in the same controller.

have anyone faced an issue like this ?

The same issue is having in another controller also. But I have two more controllers with the same IOS , which are working fine.

I have this problem too.
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Scott Fella Wed, 03/10/2010 - 05:06

What type of WLC?  Just to take a guess.... do you have more than one port on the WLC connected to your switch?  That could be why... If you have a 4400 and using multiple ports on the WLC, make sure you either use LAG or you have an AP Manager interface per por.  If you are using a 2100 and multiple vlans connected to trunk ports... make sure you not allow the management and ap manager vlan on the other ports and vice versa.

Mohamed Shafeer Wed, 03/10/2010 - 06:01

Hey Scott...

Thanks for ua quick response.

We have controller 4402.

We have all the two ports connected to core. But we have enabled LAG as well.

It was working perfect since almost an year and half. Recently we had an image upgradation to

Upgradation was done for all the 5 controllers. But two are having this error log since then.

Its not continously coming.. Only sometimes..

Scott Fella Wed, 03/10/2010 - 06:35

If you see duplicate mac errors on the switch, then there might be an issue with the LAG.  Double check your configuration on the switch and the WLC and maybe remove LAG and re apply LAG to the WLC and reboot:)  I know that if you still have issues the last case senerio is to reload the code and confgiure the WLC from scratch... don't upload configuration.

weterry Wed, 03/10/2010 - 06:37

So you have lag enabled, and the core has a port-channel configured accordingly?

I'm guessing your APs are not dropping off the controller though (which is usually what happens when the AP-Manager has a duplicate IP)...

Jacob Zartmann Fri, 05/14/2010 - 03:44

Hello shafeer82,

Did you fix this issue and how?

We're, out of nowhere, having the same issue with a couple of our 4402s... They run different versions (        and         and also have LAG configured.



Mohamed Shafeer Fri, 05/14/2010 - 15:05

I had talked to CISCO guys @ Networkers Bahrain. What they told me is that, this bug hasnt solved till now. We will have to wait till version 7 to release.

But they have already confirmed to me that this log doesnt have any kind of impact on the performance.

So be cool...


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