A monitoring device 1 includes an individual alarm reception unit 10 configured to receive individual alarms issued from a plurality of devices constituting an optical transmission network, a table 20 in which a search operator for searching for necessary information, that is information required for treating the individual alarms in the same manner when specifications of the individual alarms are different from each other, is associated with information included in the individual alarms, a search operator extraction unit 30 configured to extract the search operator using the information included in each of the individual alarms as a key, a rule 40 in which the search operator is associated with the necessary information; and a unified alarm information generation unit 50 configured to search the rule 40 using the search operator as a key, compare the information included in the individual alarms with the necessary information corresponding to the search operator, and add information, that is included in the necessary information but not included in the individual alarm, to the individual alarm to generate unified alarm information.

The amount of current provided to a laser diode of an optical network transceiver device, the power output of the optical network transceiver device, and the device temperature of the optical network transceiver device is monitored. Based at least in part on a detected fluctuation in at least one of the amount of current provided to the laser diode, the power output of the optical network transceiver device, and the device temperature of the optical network transceiver device, a determined expected life of the optical network transceiver device is dynamically adjusted.

A transmission apparatus executes a reception processing that receives a first alarm detected in a first transmission apparatus different from the own apparatus from among a plurality of transmission apparatus from a second transmission apparatus different from the own apparatus from among the plurality of transmission apparatus, executes a detection processing that detects a second alarm of the own apparatus, executes a mask processing that masks alarms including the first alarm received by the reception processing and the second alarm detected by the detection processing, and executes a sending processing that sends an alarm that is not masked by the mask processing from among the alarms to a third transmission apparatus different from the own apparatus and the second transmission apparatus from among the plurality of transmission apparatus or sending the alarm to a given apparatus different from any of the plurality of transmission apparatus.

Disclosed herein are an optical network unit and a method for controlling the unit. In a passive optical network system, an optical transceiver of the optical network unit performs a wavelength change of an optical signal according to a wavelength setting command transferred from a media access control (MAC) unit and monitors a wavelength change state and reports the monitored wavelength change state to the MAC unit. When the wavelength malfunction occurs, the MAC unit blocks an uplink optical transmission of the optical transceiver.

An optical network comprising an optical network element comprising a first optical transmitter, a first controller, an optical receiver, a second optical transmitter, a second controller and optical receiver apparatus. Said first controller is arranged to control said first optical transmitter to generate and transmit a first optical signal in response no second optical signal being detected. Said first controller is arranged to iteratively generate and transmit said first optical signal at different wavelengths of a plurality of wavelengths until said second optical signal is detected, and is further arranged to subsequently maintain generation and transmission of said first optical signal at said wavelength at which said second optical signal is detected. Said second controller is arranged to control said second optical transmitter to generate and transmit said second optical signal following detection of said first optical signal by said optical receiver apparatus.

A method in an Optical Line Terminal (OLT) device for transmitting a flow control message to an Optical Network Unit/Terminal (ONU/T) device in a Passive Optical Network (PON) access network is provided. The OLT device is configured to receive alarm and/or Attribute Value Change (AVC) messages from the ONU/T device. The OLT device is also configured to temporarily store the alarm and/or AVC messages in a message queue. The OLT device generates a flow control message indicating that the ONU/T device is to stop transmitting alarm and/or AVC messages to the OLT device, when the number of alarm and/or AVC messages in the message queue exceeds a first threshold. Then, the OLT device transmits the flow control message to the ONU/T device(s). An OLT device for transmitting a flow control message to an ONU/T device, and an ONU/T device and related method for receiving a flow control message are also provided.

Disclosed herein are an optical network unit and a method for controlling the unit. In a passive optical network system, an optical transceiver of the optical network unit performs a wavelength change of an optical signal according to a wavelength setting command transferred from a media access control (MAC) unit and monitors a wavelength change state and reports the monitored wavelength change state to the MAC unit. When the wavelength malfunction occurs, the MAC unit blocks an uplink optical transmission of the optical transceiver.