When you enable periodic replication, every 15 minutes the RADIUS primary server checks for changes to the RADIUS data and, when changes are found, replicates the RADIUS data to all of the available RADIUS replica servers in your deployment. After replicating the data, the primary server verifies that each RADIUS replica server is up-to-date. If a RADIUS replica server fails to update, the RADIUS primary server logs a message to the system log and to the Critical System Event Notification system, which can be configured to send e-mail messages to designated personnel.
In the Security Console, click Setup > System Settings.
Under Advanced Settings, click RADIUS.
Under RADIUS Replication Configuration, for Periodic RADIUS Replication, select Enable periodic RADIUS Replication every 15 minutes.