A system and method are presented for demarcating an optical network. The system comprises an optical monitor that receives a portion of an outbound signal from an optical network and generates a switch control signal based on the intensity of the outbound signal. Generally, the switch control signal is active when the intensity of the outbound signal falls below a threshold value. Alternatively, the system comprises an override switch, and the switch control signal is active when the override signal is activated or the outbound signal falls below a threshold value. An optical switch receives the switch control signal, and selectively isolates the network generating the outbound signal from the rest of the network when the switch control signal is active. The method for demarcating an optical network comprises generally coupling both the inbound signals of first and second networks and the outbound signals of the networks, and selectively isolating the first and second networks by looping signals back into the networks when the outbound signal of the second network falls below a threshold value.