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New Member

Wireless LAN Controller

Hi everyone,

I have a challenge in configuring the wireless lan controller.

The challenge am having is that after configuring the controller with the necessary parameters, the controller could not register any of the light weight APs.

How will i configure the controller to register the 5 APs.


  • Security and Network Management
Cisco Employee

Re: Wireless LAN Controller

Hi Samson,

Could you clarify on the WLC platform/ver and AP models.Have you configured the dhcp option 43 with the WLC management IP.

Including some links which will clarify this in more detail:

Lightweight AP (LAP) Registration to a Wireless LAN Controller (WLC)

Wireless LAN Controller and Lightweight Access Point Basic Configuration Example

Troubleshoot a Lightweight Access Point Not Joining a Wireless LAN Controller

DHCP OPTION 43 for Lightweight Cisco Aironet Access Points Configuration Example

Deploying Cisco 440X Series WLC:

If you still have issues after config corrections, then you can also enable debug lwapp/capwap on WLC cli and verify AP console output for further troubleshooting.



New Member

Re: Wireless LAN Controller


New Member

Re: Wireless LAN Controller

Hi Alex,

Thanks for your reply.

The WLC is 2112 version while the AP model is 1131.

Must I use an external device to do the DHCP? I've configured them but still not successful.

Please advise.


Cisco Employee

Re: Wireless LAN Controller

Hi Samson,

As you indicate WLC 2112 and ver seems to be the WLC bootloader version.Your WLC will probably have a version of 5.1 or higher (as these are the available versions on Cisco download site for the WLC 2112 model).

Whats the DHCP server in your setup and how have you configured option 43 on your DHCP server.

From one of the links provided earlier ,you will have some examples of dhcp config for Windows DHCP server/IOS DHCP Server/Linux DHCP server.

As example, from the links for DHCP on IOS:
ip dhcp pool
option 43 hex

For the hexadecimal string in Option 43,this is obtained from:
Type + Length + Value

"Type" is always the sub-option code 0xf1.
"Length" is the number of controller management IP addresses times 4 in hex.
"Value" is the IP address of the controller listed sequentially in hex.

For example, suppose that there are two controllers with management interface IP addresses, and
The type is 0xf1. The length is 2 * 4 = 8 = 0x08.
The IP addresses translate to 0a7e7e02 ( and 0a7f7f02 (
Assembling the string then yields f1080a7e7e020a7f7f02.

The IOS command then added to the DHCP scope is:
option 43 hex f1080a7e7e020a7f7f02

If issues still exist following config check, then you can troubleshoot this by investigating on logs:

From WLC cli, save logging to txt output:
debug mac addr
debug capwap event enable
debug capwap error enable
debug dtls all enable
debug pm pki enable
debug disable-all (to disable debugs after problem replication)

Simultaneously when logging above output, you can also log AP console output.
On AP console:
debug capwap console cli
debug capwap client event
debug capwap client error
debug dtls client event
undebug all (to disable debugs after problem replication)

Capture the WLC/AP debug output for some minutes until you see the image download loops from AP console.