A
bypass switch is a hardware device that provides a fail-safe access port for an in-line monitoring appliance such as an
intrusion prevention system (IPS), firewall, WAN optimization device or unified threat management system. In-line monitoring appliances are single points of failure in computer networks because if the appliance loses power, experiences a software failure, or is removed, traffic can no longer flow through the link. The bypass switch removes this point of failure by automatically shunting traffic around the appliance whenever the appliance is incapable of passing traffic.