A method of establishing communication between an optical line terminal and an optical network unit within an optical access network includes receiving a signal indication from an optical transceiver of an optical line terminal. The signal indication includes: (i) a loss-of-signal indication indicating non-receipt of an upstream optical signal from the optical network unit; or (ii) a signal-received indication indicating receipt of the upstream optical signal from the optical network unit. The method includes determining whether the signal indication includes the loss-of-signal indication. When the signal indication includes the loss-of-signal indication, the method includes instructing the optical transceiver to cease signal transmission from the optical transceiver to the optical network unit. Moreover, when the signal indication includes the signal-received indication, the method includes instructing the optical transceiver to transmit a downstream optical signal from the optical transceiver to the optical network unit.

An output port switching unit that connects to a first optical transmission path, a second optical transmission path, and the connection information processor, and sets a destination of the first optical transmission path as the connection information processor in an initial state. A controller that transmits transmission mode information indicating a transmission mode identified based on connection information of the first optical transmission path acquired from an optical signal transmitted by an optical transceiver provided in an optical communicator that the connection information processor connects to the first optical transmission path, connection request data included in the optical signal and transmitted by the optical transceiver, and transmission path information of the second optical transmission path to the optical transceiver through the first optical transmission path. The output port switching unit performs switching processing of switching a destination of the first optical transmission path from the connection information processor to the second optical transmission path after the controller transmits the transmission mode information.

A procedure for transferring wavelengths, and a system that operates in accordance with the procedure. The system comprises at least one network terminal, each including a switch and a controller. A plurality of wavelength sets are applied to the switch. The controller is arranged to operate the switch such that the switch (a) selects at least one wavelength from at least one of the plurality of wavelength sets, based on electrical monitoring at a port module external to the network terminal, and (b) outputs the at least one wavelength to an output of the at least one network terminal.

In response to a connectivity disruption in an underlying optical transport ring supporting a routing and packet switching topology, one or more of optical devices of the optical transport ring are modified to establish connectivity between spine nodes in different data centers to reroute communication between at least a subset of the leaf network devices so as to traverse an inter-spine route via the optical modified optical transport ring. That is, in response to a connectivity disruption in a portion of underlying optical transport ring, one or more optical devices within the optical transport ring are modified such that packets between at least a portion of the leaf devices are rerouted along optical paths between at least two of the spine network devices.

A communication device configured to include a communication unit a monitoring unit, a control unit, and an authentication unit. The communication unit transmits and receives an optical signal to and from an opposed device via a transmission line. The monitoring unit monitors a transfer state of the transmitted optical signal. The control unit transmits a signal based on a dummy pattern instead of actual data when the monitoring unit detects that a failure occurs in transfer of the optical signal. The authentication unit authenticates start of transmission of a signal based on the actual data, when the monitoring unit detects elimination of the failure, while the signal based on the dummy pattern is being transmitted. Moreover, the control unit transmits the signal based on the actual data instead of the dummy pattern when the start of transmission is authenticated by the authentication unit.

A method of establishing communication between an optical line terminal and an optical network unit within an optical access network includes receiving a signal indication from an optical transceiver of an optical line terminal. The signal indication includes: (i) a loss-of-signal indication indicating non-receipt of an upstream optical signal from the optical network unit; or (ii) a signal-received indication indicating receipt of the upstream optical signal from the optical network unit. The method includes determining whether the signal indication includes the loss-of-signal indication. When the signal indication includes the loss-of-signal indication, the method includes instructing the optical transceiver to cease signal transmission from the optical transceiver to the optical network unit. Moreover, when the signal indication includes the signal-received indication, the method includes instructing the optical transceiver to transmit a downstream optical signal from the optical transceiver to the optical network unit.

A communication system includes a source node and an end node of a first working path, a source node and an end node of a second working path, and a source node and an end node of a common path serving as a protection path shared by the first and second working paths. The source node of the common path transfers one of signals received from the source nodes of the first and second working paths to the common path, and the end node of the common path transmits the signal received through the common path to each of the end nodes of the first and second working paths.

A framer in a transmission device allocates plural optical channel time slots to a plurality of logical prioritized paths. It allocates received client signals to the allocated time slots, and transmits the client signals by a plurality of optical subcarriers that use a plurality of optical wavelengths corresponding to the plurality of time slots. The framer includes: a time slot allocation unit that, in a case where an optical wavelength corresponding to a time slot allocated to a logical path having a high transmission priority is not used, allocates at least one of the plurality of time slots to the logical path having the high transmission priority while the time slot corresponding to the unused optical wavelength is avoided, to change the time slot allocated to the logical path having the high transmission priority.

In some embodiments, an apparatus includes an optical transceiver that includes a first set of electrical transmitters operatively coupled to a switch. Each electrical transmitter from the first set of electrical transmitters is configured to transmit an electrical signal from a set of electrical signals. In such embodiments, the switch is configured to switch an electrical signal from the set of electrical signals such that the set of electrical signals are transmitted via a second set of electrical transmitters. Each electrical transmitter from the second set of electrical transmitters is operatively coupled to an optical transmitter from a set of optical transmitters. The set of optical transmitters is operatively coupled to an optical multiplexer. In such embodiments, at least one electrical transmitter from the second set of electrical transmitters is associated with a failure within the optical transceiver.

A method of local path protection in a node on a shared alternative path of a network. The method comprising receiving a signal switched on a primary label switched path (LSP). The signal is switched by lambda-switching or time-division multiplex TDM switching. The method further comprises receiving identification information arranged to identify the signal, and forwarding the signal on the alternative path based on the identification information.