I am trying to get some clarity on how the backup controllers work. here is a scenario 2 controllers one in Site A and one in Site B. The APs in Site B have SSID tsunami-123 are mapped to VLAN 45. If the Site B controller went down and their backup controller is in Site A what do I have to have on the backup controller to support the Site B APs? Do I have to have the same VLAN # and the same SSID on the backup controller? What i am trying to understand is how to configure the backup controller to be able to support the users that will now be on the Site A controller.