An administrator currently has one Aruba Mobility Controller in the network. Because of the company's rapid growth, the administrator plans to purchase three additional controllers that will be…

An administrator currently has one Aruba Mobility Controller in the network. Because of the company's rapid growth, the administrator plans to purchase three additional controllers that will be configured in a local operating mode. The administrator wants to protect the messages between the existing master controller and the three local controllers. Which Aruba Mobility Controller feature needs to be configured to provide this protection?