Bypass switch
A bypass switch (or bypass TAP) is a hardware device that provides a fail-safe access port for an in-line active security appliance such as an intrusion prevention system (IPS), next generation firewall (NGFW), etc. Active, in-line security appliances are single points of failure in live computer networks because if the appliance loses power, experiences a software failure, or is taken off-line for updates or upgrades, traffic can no longer flow through the critical link.