Interface Monitoring - D-Link DFL-1100 User Manual

When this is done click Apply.
Now login to the slave firewall and go to System > HA; in this screen you will click on
Receive configuration from first unit. This will show the screen below; here you will fill in
the cluster ID configured on the first unit. When you click Apply the unit should transfer the
configuration from the first unit, and your HA cluster should be operating.

Interface Monitoring

When HA is configured it's possible to configure something called Interface Monitoring, this is
used to monitor up to 6 IP addresses on each segment (LAN/WAN or DMZ) of the DFL-1100
cluster. If 50% of the listed addresses are unreachable for several seconds, the active node
will failover and the other unit will become active.