N+1 High Availability Configuration on Cisco 2504WLC

Yesterday I implemented N+1 HA configuration on my lab with Cisco 2504 WLC. Earlier tried to find a guide especially for 2504 Controller but didn’t get on Cisco web. That’s the reason I thought to create a post about this, may be it will be helpful for others.

Few Remembering points:

  • The N+1 HA setup provides redundancy for controllers across separate data centers with low cost of deployment.
  • These WLCs are independent of each other and do not share configuration or IP addresses on any of their interfaces. Each WLC needs to be managed separately, can run a different hardware and a different software version, and can be deployed in different datacenters across the WAN link.
  • We must configure and manage both WLC separately.
  • When a primary WLC resumes operation, the APs fall back from the backup WLC to the primary WLC automatically if the AP fallback option is enabled.

For more info: N+1 HA Deployment Guide

N+1 HA Configuration via GUI:

Step1: Configure both WLC’s and just make sure the hostname and IP address used for management and the dynamic interfaces are different.

Step2: Go to Primary Controller GUI and navigate to Wireless > Access Points > Global Configuration, then configure the backup controller on the primary to point to the secondary controller.

GlobCon

Step3: Configure High Availability to input Primary and Backup controller IP Address at Wireless AP.

Go to Wireless > Access Point > All APs, select specific AP and then Click on High Availability tab.

Enter the primary WLC, secondary WLC IP and name here. Make sure that the WLC name we entered on the AP high availability tab is correct and is case sensitive.

Step4: Configure Mobility Group on both Primary and Secondary Controllers.

Go to Primary WLC GUI then navigate to Controller > Mobility Management > Mobility Groups and then click on new, enter the details of secondary controller.

Mob1

Same on secondary WLC:

Go to Secondary WLC GUI then navigate to Controller > Mobility Management > Mobility Groups and then click on new, enter the details of Primary controller.

Mob2

Step5: Enable Secondary Unit

Via GUI:

Go to Secondary Controller GUI and navigate to Controller then enable the AP Fallback (Enable on both WLC) & HA SKU secondary unit from drop down option.

Via CLI:

Execute the config redundancy unit secondary command to obtain support for Max AP count licenses on a given hardware.

(WLC2) >config redundancy unit ?
 primary        Redundancy unit type is primary
 secondary      Redundancy unit type is secondary
 (WLC2) >config redundancy unit secondary

Make sure:

  1. After this entire configuration we must save the config by Save configuration via GUI or save config from CLI on Both WLCs .
  2. Reboot Secondary WLC to take effect of (config redundancy unit secondary) this command.(According to my test, if you will not reboot this WLC after applying this command AP failover will not happen)

VERIFICATION

(WLC1) >show redundancy summary
 Type of the Unit = Primary
 (WLC1) >
(WLC2) >show redundancy  summary
 Type of the Unit = Secondary
 (WLC2) >
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127 thoughts on “N+1 High Availability Configuration on Cisco 2504WLC

      1. Thanks,

        I have also found that and got confirmation from CISCO that it does not support WLC 2504.

        Bye..
        Sourav

  1. Step3: Configure High Availability to input Primary and Backup controller IP Address at Wireless AP.

    Go to Wireless > Access Point > All APs, select specific AP and then Click on High Availability tab.

    ^ This step, can you confirm if this only needs to be actioned on the Primary unit? Or should this be done on the secondary unit aswell? Thanks

  2. I have 2 2504 WLC with 25 AP as base license, If I have to convert one WLC to HA-SKU mode for failover, what will happen to 25 AP licenses, will it get scraped or I can use it in the primary WLC

    1. You can/can’t use the AP license from 2nd controller: better to contact CIsco TAC and (possibly)rehost these license and upload to primary WLC to make the total 50.

  3. Thanks for this post. Question I have, do you need to configure all of the WLAN’s/etc on the secondary controller? How much configuration needs to be in place on that secondary controller for the failover to work?

    1. If you are using 2504 WLCs then you need to configure both WLCs separately with same configuration except IP address and name of WLC. For failover, you need to add both WLCs in each other mobility list and also add WLC ip/Hostnamen in global config of both WLCs.
      Regards

  4. Also wondering how you verify this configuration is working. Should you see the other controller connected in the mobility group? Mine shows the other controller in the group as “Control and Data path Down”? Should you see AP’s populate on the secondary controller? Can’t find much on doing this with the 2504 controllers. Thanks

      1. I did, and I can run the ping command from each of the WLC’s and it’s successful. Not sure what else I need to do?

  5. Thanks for all of your help.
    I found the problem, the “default group” was identified differently between the controllers. You have to make sure the “default mobility domain name” is the same on both units. You can set this on the general tab of the controller menu.

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