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Note Make sure that the controller is set to the current time. If the controller is set to a time that
has already occurred, the access point might not join the controller because its certificate may
not be valid for that time.
Access points must be discovered by a controller before they can become an active part of the network.
The access point supports these controller discovery processes:
• Layer 3 CAPWAP discovery—Can occur on subnets different from that of the access point and
uses IP addresses and UDP packets.
• Locally stored controller IP address discovery—If the access point was previously joined to a
controller, the IP addresses of the primary, secondary, and tertiary controllers are stored in the
access point’s non-volatile memory. This process of storing controller IP addresses on an access
point for later deployment is called priming the access point. For more information about priming,
see the “Performing a Pre-Installation Configuration” section on page 13.
• DHCP server discovery—This feature uses DHCP option 43 to provide controller IP addresses to
the access points. Cisco switches support a DHCP server option that is typically used for this
capability. For more information about DHCP option 43, see the “Configuring DHCP Option 43”
section on page 39.
• DNS discovery—The access point can discover controllers through your domain name server
(DNS). For the access point to do so, you must configure your DNS to return controller IP
addresses in response to CISCO-CAPWAP-CONTROLLER.localdomain, where localdomain is
the access point domain name. Configuring the CISCO-CAPWAP-CONTROLLER provides
backwards compatibility in an existing customer deployment. When an access point receives an IP
address and DNS information from a DHCP server, it contacts the DNS to resolve
CISCO-CAPWAP-CONTROLLER.localdomain. When the DNS sends a list of controller IP
addresses, the access point sends discovery requests to the controllers.
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