Cisco WLC HA failure scenario

Some days ago I tested the HA WLC cluster at one of my customer. This is the environment:

– First WLC (let’s call it “Main-WLC”) with 172.16.1.10 (with shared management IP 172.16.1.30)
– Second WLC (let’s call it “HA-WLC”) with 172.16.1.20 (with shared management IP 172.16.1.30)

We powered-off the Main-WLC, the access points and wireless clients didn’t notice a failure/disconnect. I had only one ping loss. If you go the management webinterface you can see the following:

Peer State: UNKNOWN – Communication Down
Unit: Secondary – HA SKU (Inherited AP License Count = 100)
Redundancy State: Not Redundant

As you can see there is also a switchover history log entry with “Active controller failed”. The copied license is now valid for the next 60 days. In this time you need to replace the “broken” WLC. We powered-on the Main-WLC  and the Peer State changed to “STANDBY COLD”, the active device is still the HA-WLC (the secondary one). There is no prefered master configuration. After the Main-WLC has downloaded the configuration from the HA-WLC it restarts again and the Peer State changed to “STANDBY HOT”:

To make the Main-WLC the primary WLC, we made a manuell takeover. Connect via SSH to the management ip address (172.16.1.30 in our case) and type in the following command:

redundancy force-switchover

This will force the Main-WLC to be the active one. There was only one ping loss, everything else works fine! You can see this also in the switchover history table as “user initiated”. The secondary HA-WLC will restart, download the configuration and the license storage from the Main-WLC and will restart again. The perfect state of a Cisco WLC cluster would be this:

Local State: Active
Peer State: STANDBY HOT
Unit: Primary
Redundancy State: SSO (Both AP and Client SSO)

Feel free to share your thoughts and experience in the comments below!