The Cisco Catalyst 9800 wireless controller can be upgraded using a variety of methods, including:
- Software Maintenance Upgrade (SMU): Installs a software package to fix bugs or provide security updates
- Hitless Upgrade: Upgrades APs in stages while they remain connected to the controller.
- Software Maintenance Upgrade (SMU): This method is used to fix bugs or provide security updates.
- Hitless Upgrade: This method allows APs to be upgraded in stages while they remain connected to the controller.
- In-Service Software Upgrade (ISSU): Upgrades a wireless controller image to a newer release while the network continues to function.This method is ideal for 24/7 environments because it minimizes downtime. It can also be used to apply cold patches without impacting the active network.
Verify the that the devices are in HA/SSO mode


Log into the GUI of the primary 9800












The device will reboot and reinitialize HA










Verify that both devices were successfully upgraded
