The ComNet CN-OB(M,S) external bypass switches for 100M/1G/10G fiber optic networks protect the network from failures and ensure network integrity during power loss. Each of these fiber optical bypass switches includes Network ports and Monitor ports. The Network ports are used for connection to main-network connections and provide protection mechanism, and the Monitor ports are used for down-link local networking device. When the power is on, the operation mode of the Bypass switch is set to Normal, and the local networking device is connected with main-network. When power failure occurs, the Bypass switch is swiftly set to bypass mode to isolate the mainnetwork from the local networking device.