Select a concentrator from the list, then select Add. You can add up to three concentrators to a single topology. When more than one termination point is added to the list, failover is supported.
Note
It is a best practice to configure more than one Tunnel Concentrator per VLAN topology for failover. A topology that uses a single generic (non-encrypted) GRE tunnel, without configured backups, is not using the available mechanisms to detect if a Tunnel Concentrator is down. Therefore, no AP alarms, related to the tunnel connectivity, are generated for such a topology.