# Backup Interface

When primary and backup interfaces are both bound to the Untrust zone, you can switch traffic from the primary interface to the backup interface and from the backup interface to the primary interface. By default, there is a 30-second interval before the switchover occurs.

You can configure the device to automatically switch to the backup interface if ScreenOS detects a failure on the primary interface connection. When the connection through the primary interface is restored, ScreenOS automatically switches traffic from the backup to the primary interface.

If the primary interface is up, the backup interface is forced down. If the primary interface becomes unavailable, the backup interface activates. If the backup interface is an ISDN interface, it will dial a connection.

Edit the following options to configure a backup Interface:

### Primary Interface: Select the primary interface from the drop-down list.

### Backup Interface: Select the backup interface from the drop-down list.

### Type: Select one of the following three methods to determine if the primary interface is unavailable:

- track IP Enables the backup interface when certain IP addresses become unreachable through the interface.

- tunnel Interface Enables the backup interface when certain VPN tunnels on the interface become unreachable through VPN tunnel monitoring.

- route vrouter: Enables the backup interface if the preconfigured route becomes unreachable through the interface.

- route vrouter Select a vrouter.

- IP/Netmask Specify the IP address and netmask of the preconfigured route.

Click Apply.

Click Edit in the list of configured interfaces to modify settings. Click Remove to remove a backup interface configuration.

Your updates or additions are displayed in the Interface table.