High Availability (HA) allows two identical SonicWALL appliances running SonicOS to be configured to provide a reliable, continuous connection. One SonicWALL device is configured as the Primary unit, and an identical SonicWALL device is configured as the Secondary unit. If the Primary SonicWALL fails, the Secondary SonicWALL takes over to secure a reliable connection between the protected network and the Internet. Two appliances configured in this way function as a High Availability Pair.