Primary and secondary controllers

Connection establishment between an access point and the WLAN controller is always initiated by the access point. A LANCOM access point in managed mode will search the LAN for a WLAN controller that will provide the configuration. During this search the access point may find various suitable WLAN controllers:

• The WLAN controller can authenticate the certificate in the access point and it has a configuration stored for the access point's MAC address. A WLAN controller of this type is described as a "primary" WLAN controller.
• A WLAN controller can authenticate the certificate of an access point, but it has neither a configuration stored for the MAC address of the access point, nor does it have a default configuration. A WLAN controller of this type is described as a "secondary" WLAN controller.

This is an example of a backup solution with three WLAN controllers for 50 managed access points: Two of the WLAN controllers each manage 25 access points and the third is available as a backup:

1. Set the same time on all of the WLAN controllers 1, 2 and 3.
2. Transfer the CA and RA certificates from the first primary WLAN controller 1 to the second primary 2 and to the secondary "backup controller" 3.
3. Configure the first WLAN controller 1 according to your requirements with the profiles and the associated AP table for one half of the access points. This WLAN controller becomes the primary controller for the access points entered into it.

Once the access point has established a backup connection to a secondary WLAN controller, the countdown until expiry of standalone operation is halted. The access point and its WLAN networks remain active as long as it has a connection to a WLAN controller.

1. Configure the second WLAN controller 2 for the other half of the access points, which subsequently treat this WLAN controller as their primary controller.
2. For the backup controller 3 the time and the root certificates are set up only. No further configuration is required.
3. After being started, the access points search for a WLAN controller by emitting a discovery message. In this case, all three LANCOM WLAN controllers respond to this message—the access points select "their" primary controller for the DTLS connection that follows. One half of the access points decides on WLAN controller 1 and the other half chooses WLAN controller 2. Because WLAN controller 3 does not function as primary controller for any of the access points, none of the access points log on to it.
4. Should WLAN controller 2 fail, the access points will automatically search for another WLAN controller. They discover the WLAN controllers 1 and 3, whereby 1 is already under full load with its 25 access points. Backup controller 3 is able to check the validity of the certificates, i.e. it can authenticate the access points and accept them as managed access points. However, because the access points are not entered with their MAC numbers into the backup controller's AP table, the backup controller cannot manage the access points any longer; they simply continue to operate with their current WLAN configurations.