Stateful hardware fail-over is a feature that provides the same options as basic hardware fail-over with a list of new features that increase reliability and functionality.
With Stateful HA, connections are now constantly cached across the units which decreases the fail-over time and nearly puts the possibility of connection failures due to fail-over to less than 10 percent. The Virtual MAC is a new feature as well which allows like interfaces of the units to share the same MAC address. This negates the possibility of ARP caches from routers/switches/machines on the network causing issues when the fail-over occurs since they do not need to be updated anymore which has resulted in the inability to connect completely in situations where gratuitous ARP was not accepted and by firewall standards would generate an IP spoof. An audible alarm, and a test light sequence for the backup unit that mimics a fast heartbeat, are also new features added that have their obvious uses. These features, the connection caching, and the slightly more aggressive fail-over heartbeat monitoring create a superior hardware fail-over feature that is seemless in transition.