2106 not giving more than 1 IP address from DHCP server

Unanswered Question
Jun 18th, 2008

I have a 2106 controller setup and all the APs associate to it fine. I can access the web interface fine. When we add machines to the wireless network we start getting "IP address conflict" in Windows XP. The network is one subnet with 3com switches on native VLAN1.

The controller:

Management: Untagged Port 1

AP Manager: Untagged Port 1


DHCP Server is

The code is 4.2.112 and using Windows 2003 server for DHCP. The APs are getting different addresses, but the clients are not.

I am thinking of running "config dhcp proxy disable" to see if that corrects the issue, but I dont know if that is the right route to take.

Anyone have any ideas?

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Scott Fella Wed, 06/18/2008 - 15:03

Recheck your configuration on your wlc and also your ip helper address on your layer 3 interface.

mrjsprague Fri, 06/20/2008 - 06:38

I looked over the configuration again and everything seems fine. I talked with the IT staff about a helper statement and they said they dont have one because their network is one big network. They only have the one vlan.

Would it be possible to run DHCP off the controller to try to narrow down the problem? We could add a range of addresses to exclude from the DHCP server and run them on the controller instead.

Scott Fella Sat, 06/21/2008 - 11:13

You can do that.... One thing you should know is that it is recommended that your wireless users are not placed on the same subnet as the wired. This has caused issues in the past and that is why its not recommended to have a mixed subnet.

mrjsprague Thu, 06/26/2008 - 13:19

I have tried the DHCP server running on the controller and we still get that error.

Since the 2106 only does layer 3 LWAPP, if we changed to a 4400 series controller that can do layer 2 LWAPP, would that work in this environment?

Thanks fella5 for the information you provided.

Scott Fella Thu, 06/26/2008 - 13:34

Layer 2 is only supported in the old airspace ap's. Post your show run-config.... so we can see if there is a configuration issue.

Scott Fella Thu, 06/26/2008 - 17:38

Looking at your configuration, here is what I would change:

1) Upgrade the boot loader to 4.2.112

2) Disable Ethernet Multicast unless you are using it.

3) Add the secondary DHCP to the AP-Manager interface (for consistency)

4) Remove the DHCP override on the bcmh profile. It is pointing to a DHCP server of

5) Disable WMM unless you have IP phones

6) bcmh is configured for WEP, so verify the client is setup correctly.

That is all for now. Hope this helps.


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