Routing-Based Sensor High Availability

The routing-based high availability is another method to provide network-based HA. It is achieved by running a routing protocol over paths where the IPS sensors are installed in inline or promiscuous mode. This method can provide both active-active and active-standby HA, depending on how the routing protocol is configured.

When a routing protocol learns multiple paths to a specific destination network, the router chooses the path with the lowest metric to the destination. It will use the alternative route should the preferred route cease to exist, and this is the concept of active-standby, where the preferred route is through the primary IPS sensor and the alternative or less preferred route is through a secondary IPS sensor.