I have 4 controllers(2 WISMS) on one controller "Fast SSID Change" is enabled.
I want to disable it, will the cause and outage on that particular controller? Or can it be done on the fly?
Fast SSID makes the IP address assignment process fast when a client roams. You can change this setting on the fly...no reboot of anything will be required.
If you are using a single SSID throughout the network you have nothing to lose in terms of roaming speeds. But if the client can connect to more than one WLAN because of the availability of SSIDs then the connection speed will reduce while roaming.