IP Network Failover settings

The IP Network Failover feature provides a dynamic method for selecting and configuring the default gateway for the Digi device. Failover uses of a set of rules and link tests to determine whether you can use a particular network interface to communicate with a specified destination. The user configures these rules, link tests and the priority order of the interfaces.

Failover maintains a network interface list, ordered by the configured Failover Interface Priority, and containing information on the state of the network interface and recent success or failure of the link tests for that interface. The failover status for a network interface is one of the following:

• 1 - Responding: The interface is Up and configured in the system. It is currently responding to the link tests. This interface is suitable for use as the default gateway.
• 2 - Up: The interface is Up and configured in the system. Its status has not been determined by the link tests, or no link tests are configured. This interface may be suitable for use as the default gateway.
• 3 - Not Responding: The interface is Up and configured in the system. However, it is not currently responding to the link tests, and the number of consecutive test failures has reached the threshold number configured in the Network Failover settings. This interface may be suitable for use as the default gateway.
• 4 - Down: The interface is Down or not configured in the system. However, it is not currently responding to the link tests. This interface is not suitable for use as the default gateway.
• 5 - Unknown: The interface is Unknown (does not exist) in the system. This interface is not suitable for use as the default gateway.

The number shown above for each status value, indicates the priority of that status, failover uses in selecting the interface to use as the default gateway. Status priority 1 is the most suitable for use, with lower priorities considered suitable if there are no interfaces at the highest priority.

When any network interface changes status, the interface list is examined for the interface that has the highest status priority, nearest the start of the list. The default gateway is the highest priority interface with a Responding status. If no interface is marked Responding then the default gateway is highest Up interface.

When Network Failover performs a link test, it adds a temporary static host route to the destination IP address for the link test, using the network interface that the link test is configured to test. The static host route is removed when the link test completes. Avoid manually configuring static host routes to any of the failover link test destinations, as such host routes may interfere with failover's link testing. Static IP routes are configured on the IP Forwarding Settings page. For additional information, see IP forwarding settings.

In the Advanced Network Settings, the Gateway Priority selection provides a simpler method for selecting the default gateway. However, if failover is properly configured and enabled, it overrides the Gateway Priority selection in the Advanced Network Settings. For a description of this non-failover Gateway Priority selection and information on how to configure it, see Advanced Network Settings.

For IP Network Failover status and statistics, see IP Network Failover statistics.