D-Link NetDefend DFL-210 User Manual page 410

11.1. Overview
Chapter 11. High Availability
operations such as changing rules in the IP rule set are carried out as normal with the changes
automatically being made to the configurations of both the master and the slave.
Load-sharing
D-Link HA clusters do not provide load-sharing since only one unit will be active while the other is
inactive and only two D-Link Firewalls, the master and the slave, can exist in a single cluster. The
only processing role that the inactive unit plays is to replicate the state of the active unit and to take
over all traffic processing if it detects the active unit is not responding.
Hardware Duplication
D-Link HA will only operate between two D-Link Firewalls. As the internal operation of different
firewall manufacturer's software is completely dissimilar, there is no common method available to
communicating state information to a dissimilar device.
It is also strongly recommended that the D-Link Firewalls used in cluster have identical
configurations. They must also have identical licenses which allow identical capabilities including
the ability to run in an HA cluster.
Extending Redundancy
Implementing an HA Cluster will eliminate one of the points of failure in a network. Routers,
switches and Internet connections can remain as potential points of failure and redundancy for these
should also be considered.
The following sections describe the High Availability feature in greater detail.
410