Cisco WLC HA Pair

Cisco High Availability pair configuration

I did this how to blog post to show the steps I took to configure 2x 5508 Wireless LAN Controllers as part of a High availability (HA) pair.

A more detail explanation can be found at

Some techie information about HA .The High availability feature will allow for stateful switchover of the Cisco Lightweight Access Points and client sessions from the active Wireless LAN Controller (WLC) to the standby WLC.

Client SSO enables client information to be synced to the standby controller when client association or settings change. Making no noticeable network outage in the event of the primary controller failing

 Prerequisites for HA configuration:

      • Same software version
      • min of 50 AP license  on both controller or a HA SKU WLC

 Screen Shot 2017-08-04 at 5.34.05 pm.png

 Step 1:click on “CONTROLLER” TAB

Screen Shot 2017-08-04 at 5.34.12 pm.pngStep 2: Click on “Redundancy”  and then click “Global Configuration”

Screen Shot 2017-08-04 at 5.34.17 pm.png

Figure 3:Redundancy  global configuration

Step 3: Enter the IP address for “Redundancy Mgmt” and  “Peer Redundancy Mgmt”

Step 4: Select “Primary” or “Secondary”  for Redundant unit

Step 5: Click “Apply”

Step 6: Click “Enabled”  for SSO (ensure  UTP cable is plugged in to the Redundant port between  both WLC )

Connection between the two WLC’s is made by the redundancy port on both of the WLC, (picture below is off  5520 model, 5508 Redundancy ports are on the front of the controller)

Screen Shot 2017-08-04 at 5.34.24 pm.png


The Redundancy Management Interface is configured in the same subnet as the management interface. Once the Active WLC does not respond to Keepalive messages on the redundant port. The interface will check the health of the Active WLC via the Network infrastructure. This provides an additional health check of the network and Active WLC and confirms if switchover should or should not be executed.

The interface is used for Bulk configuration during boot up and incremental configuration are synced from Active WLC to the Standby WLC using the redundant port. The port will perform HA role negotiation and is also used in order to check peer reachability, sending UDP keep-alive messages every 100msec (default timer) from the Standby WLC to the Active WLC.

Layer 2 Connection can be used between the Redundancy port of the Primary and Standby WLC, as it does not require a direct connection.

Step 7: Click “apply” the WLC’s will reboot and start the negotiation

Screen Shot 2017-08-04 at 5.34.28 pm.png

**If the Standby WLC does not detect the Primary WLC after 120seconds it will boot into “maintenance mode” Reboot Standby controller again.

Once the WLC ‘s are synced the WLC 1  (Primary) will be in an active state.

WLC2 has success become part of HA indicated by ”STANDBY HOT” state


All Management of the WLC’s will be done on the Primary WLC (WLC1) as WLC2 (Standby Hot) management interface will not work, only way to access is via console connection or via SSH on the service port and on the redundant management interface.

Screen Shot 2017-08-04 at 5.34.35 pm.png

Step 8:  To Check the High Availability (SSO)  configuration was successfully, form the Monitor page click “Redundancy” and the click “Summary” if configuration was successful the output will look similar to below.

Screen Shot 2017-08-04 at 5.34.42 pm.png

Step 9: if there is issues with High availability (SSO) configuration it will display the following

Screen Shot 2017-08-04 at 5.34.46 pm.png

Step 10: Plug console into the Standby controller

      • To Display HA information in the CLI enter “ show redundancy summary”.

Screen Shot 2017-08-04 at 5.34.53 pm.png

If the Peer state indicates- Communication Down refer to the below steps.

      • Check Redandant port cable is connected correctly. “As per step 6”
      • If connected correctly test cable or replace with new cable.
      • Check both WLC’s are the same version and have the minimum AP licence required of 50+
      • Check IP address settings

Once fault has been found and if the standby controller does not reboot self after a few minutes  do a manual power cycle and watch the console output  for the  the following.

Screen Shot 2017-08-04 at 5.34.59 pm.png

Once reloaded, repeat the steps to check the HA configuration.

Upon successful completion of the above steps. Perform required network connectivity test i.e ping test by clicking on the Ping tab in the top right hand of the WLC webpage.


 Screen Shot 2017-08-04 at 5.35.05 pm.png


Cisco Wireless LAN Controllers configured as a High availability pair.

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