A method for diagnosing an optical communication network having a control system, an optical hub, and multiple optical network terminators. The hub communicates with all the network terminators via an inband management channel. In case one network terminator disturbs the communication from the network terminators to the hub and the communication from the hub to the network terminators is functional, the control system sends a shut-off command to one network terminator, checks if the disturbance is gone, if the disturbance is not gone, sends a pulse mode activation command to this network terminator, checks if there is a superposition signal of the disturbance signal with a pulse mode signal and marks the network terminator as bad, if the pulse signal is not superimposed.