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How to Configure WLC 5508 Failover

Dear All,

Thanks in Advance for your support,

I have two WLC 5508 (AIR-CT5508-25-K9) i want to configure failover between them and i have 25 access points


802.11g/n Controller-based AP; Int Ant; ETSI Cfg



802.11a,b/g Outdoor Mesh AP, ETSI Cfg 1520 Series Mesh Access Points


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Re: How to Configure WLC 5508 Failover

Here is a doc that will go through how to setup high availability for WLC's and access points.

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Re: How to Configure WLC 5508 Failover


Cisco Wireless LAN Controller Failover

During installation, we recommend that you connect all lightweight  access points to a dedicated controller, and configure each lightweight  access point for final operation. This step configures each lightweight  access point for a primary, secondary, and tertiary controller and  allows it to store the configured mobility group information.

During failover recovery, the following tasks are performed:

The  configured access point attempts to contact the primary, secondary, and  tertiary controllers, and then attempts to contact the IP addresses of  the other controllers in the mobility group.

DNS is resolved with controller IP address.

DHCP servers get the controller IP Addresses (vendor specific option 43 in DHCP offer).

In multiple-controller deployments, if one controller fails, the access points perform the following tasks:

If  the lightweight access point has a primary, secondary, and tertiary  controller assigned, it attempts to associate with that controller.

If  the access point has no primary, secondary, or tertiary controllers  assigned or if its primary, secondary, or tertiary controllers are  unavailable, it attempts to associate with a master controller.

If the access point finds no master controller, it attempts to contact stored mobility group members by the IP address.

If  the mobility group members are available, and if the lightweight access  point has no primary, secondary, and tertiary controllers assigned and  there is no master controller active, it attempts to associate with the  least-loaded controller to respond to its discovery messages.

When sufficient controllers are deployed, if one controller fails,  active access point client sessions are momentarily dropped while the  dropped access point associates with another controller, allowing the  client device to immediately reassociate and reauthenticate.

To know more about high availability, see

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