HA WLC 9800

[nstr1]

I have a question with the HA of the WLC 9800,
can I do a HA with a physical WLC and a virtual WLC ???

[Leo Laohoo]

No, it has to be like-for-like.

[balaji.bandi]

Restrictions

Prior to enabling HA between two 9800 WLCs ensure these you perform these validations:

• Both devices must be of same PID. In case of 9800-CL, ensure the hosting environment (ESXi or KVM or ENCS) is same for both instances.
• Both devices must run the same version of software.
• Both devices must be running in the same Installation Mode (Either Bundle or Install). We recommend using Install mode for WLC. 
• Both devices should have redundant IPs in the same subnet. IP address used for redundancy should be unroutable without a gateway present in the subnet.
• Both devices must have their own wireless management interface 
• Wireless management interface of both devices must belong to the same VLAN/subnet. 
• In case of 9800-CL,
  • Verify same CPU, memory and harddisk resources are allocated to both instances.
  • Verify VM snapshot is disabled for both instances.
  • Both devices must use the same interface number (For example : GigabitEthernet3) for HA

Look at the requirement :

https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/213915-configure-catalyst-9800-wireless-control.html

[Arshad Safrulla]

There are 2 HA modes,

1. HA SSO (Client and AP stateful switchover) - This will support switchover between WLC's with least possible downtime in case of failover and this is not supported in your case.

https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/213915-configure-catalyst-9800-wireless-control.html

2. N+1 - This allows a single WLC to be used as a backup WLC for N primary controllers, irrespective of the WLC's models. But you have to make sure that the number of AP's and Clients can be handled by the backup WLC incase of failover. This method can be deployed in your case and you will notice a small downtime incase of a failover. 

https://www.cisco.com/c/dam/en/us/td/docs/wireless/controller/9800/17-4/deployment-guide/c9800-n-plus-1-high-availability-wp.pdf

I have also attached some links where you can find more information. Let me know if you need anything else.