"In addition to monitoring rogue APs, you can actively prevent your users from connecting to them. When suppression is activated against an AP, the FortiGate WiFi controller sends deauthentication messages to the rogue AP’s clients, posing as the rogue AP, and also sends deauthentication messages to the rogue AP, posing as its clients."
https://help.fortinet.com/fos50hlp/54/Content/FortiOS/fortig...
"In addition to monitoring rogue APs, you can actively prevent your users from connecting to them. When suppression is activated against an AP, the FortiGate WiFi controller sends deauthentication messages to the rogue AP’s clients, posing as the rogue AP, and also sends deauthentication messages to the rogue AP, posing as its clients."