Cisco Systems OL-17037-01 manual Using Dhcp Option 43 and Dhcp Option

Chapter 7 Controlling Lightweight Access Points

Autonomous Access Points Converted to Lightweight Mode

Using DHCP Option 43 and DHCP Option 60

Cisco Aironet access points use the type-length-value (TLV) format for DHCP option 43. DHCP servers must be programmed to return the option based on the access point’s DHCP Vendor Class Identifier (VCI) string (DHCP Option 60). Table 7-1lists the VCI strings for Cisco access points capable of operating in lightweight mode.

Table 7-1	VCI Strings For Lightweight Access Points
Access Point		VCI String
Cisco Aironet 1130 Series		Cisco AP c1130
Cisco Aironet 1140 Series		Cisco AP c1140
Cisco Aironet 1200 Series		Cisco AP c1200
Cisco Aironet 1240 Series		Cisco AP c1240
Cisco Aironet 1250 Series		Cisco AP c1250
Cisco AP801 Embedded Access Point		Cisco AP801

This is the format of the TLV block:

•Type: 0xf1 (decimal 241)

•Length: Number of controller IP addresses * 4

•Value: List of the IP addresses of controller management interfaces

Refer to the product documentation for your DHCP server for instructions on configuring DHCP option

43.The Upgrading Autonomous Cisco Aironet Access Points to Lightweight Mode document contains example steps for configuring option 43 on a DHCP server.

Troubleshooting the Access Point Join Process

Access points can fail to join a controller for many reasons: a RADIUS authorization is pending, self-signed certificates are not enabled on the controller, the access point and controller’s regulatory domains do not match, and so on.

Controller software release 5.2 enables you to configure the access points to send all CAPWAP-related errors to a syslog server. You do not need to enable any debug commands on the controller because all of the CAPWAP error messages can be viewed from the syslog server itself.

The state of the access point is not maintained on the controller until it receives a CAPWAP join request from the access point. Therefore, it can be difficult to determine why the CAPWAP discovery request from a certain access point was rejected. In order to troubleshoot such joining issues without enabling CAPWAP debug commands on the controller, the controller collects information for all access points that send a discovery message to this controller and maintains information for any access points that have successfully joined this controller.

The controller collects all join-related information for each access point that sends a CAPWAP discovery request to the controller. Collection begins with the first discovery message received from the access point and ends with the last configuration payload sent from the controller to the access point.

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