The Untangle NGFW high availability approach is based on the Virtual Router Redundancy Protocol (VRRP). VRRP is a network protocol that provides redundancy and high availability when using a statically configured router on a Local Area Network (LAN).
Multiple Untangle servers can run in parallel to provide a high availability configuration. Thus, one Untangle NGFW server will be the master (that is, the server with the highest priority) and the other servers will be the slaves.
All Untangle NGFW servers must be on and configured with static IPs and with a VRRP virtual address. The master server is the only Untangle NGFW to answer/handle traffic routed to the VRRP virtual address. When the master server fails, the slave server with the next highest priority will take over the master role; thus, the network traffic will continue to flow without any interruption.