I recently received a case of Cisco 3500 AP’s. When I connected them to the network, they couldn’t find the controller. I made sure the DHCP server was setup correctly to support the c3500 AP’s. After trying another AP, I started digging some more. After consoling in, I found the following log errors.

*Mar 1 00:25:52.026: %CAPWAP-3-DHCP_RENEW: Could not discover WLC using DHCP IP. Renewing DHCP IP.
Not in Bound state.
*Mar 1 00:26:02.542: %CAPWAP-3-ERRORLOG: Invalid event 38 & state 2 combination.
*Mar 1 00:26:02.561: %DHCP-6-ADDRESS_ASSIGN: Interface GigabitEthernet0 assigned DHCP address 192.168.99.62, mask 255.255.254.0, hostname APa44c.1111.1111

Translating “CISCO-CAPWAP-CONTROLLER.domain.com”…domain server (192.168.1.5)

I configured the AP with the controllers IP address, but did not save it. Within a few minutes, it found the controller and started downloading it’s software.

The command to configure the AP to go to a specific controller
lwapp ap controller ip address XXX.XXX.XXX.XXX —> Enter controller IP

After the software change (Old version LWAPP image version 7.0.112.74), it was able to find the controller after booting up and receiving an IP address.

After some more research I found out that my DHCP settings were NOT correct, I had option 43 using IP addresses for the controllers. These AP’s need to have Option 43 setup with the HEX values.

This is how to configure the HEX value in DHCP

Under your DHCP pool config
ip dhcp pool Wireless-DHCP-POOL
option 43 [HEX Value]

The HEX Value is 3 values combined
1. f1 (it’s always f1)
2. (# of Controllers x 04) So, 3 controllers would be 0C (0C is HEX for 12)
3. The HEX Value of your IP

So here is an example

2 Controllers 1.1.1.1 & 2.2.2.2
1.1.1.1 = 01010101
2.2.2.2 = 02020202

option 43 hex f1080101010102020202

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After the AP boots up and finds the controller you will see the following logs.

*Mar 1 00:12:09.981: %CAPWAP-5-DHCP_OPTION_43: Controller address 1.1.1.1 obtained through DHCP
*Mar 1 00:12:09.981: %CAPWAP-5-DHCP_OPTION_43: Controller address 2.2.2.2 obtained through DHCP
examining image…
*Sep 28 19:46:41.000: %CAPWAP-5-DTLSREQSEND: DTLS connection request sent peer_ip: 1.1.1.1 peer_port: 5246

*Sep 28 19:46:41.575: %CAPWAP-5-DTLSREQSUCC: DTLS connection created sucessfully peer_ip: 1.1.1.1 peer_port: 5246
*Sep 28 19:46:41.575: %CAPWAP-5-SENDJOIN: sending Join Request to 1.1.1.1
*Sep 28 19:46:41.575: %CAPWAP-5-CHANGED: CAPWAP changed state to JOINperform archive download capwap:/ap3g1 tar file
*Sep 28 19:46:41.581: %CAPWAP-5-AP_IMG_DWNLD: Required image not found on AP. Downloading image from Controller.
*Sep 28 19:46:41.588: %CAPWAP-5-CHANGED: CAPWAP changed state to IMAGE

Please let me know if you have run into this same issue, did this help you resolve your issue?