Nippon Telegraph and Telephone Corporation

Kengo Shintaku

Kei Kitamura

Yoshiaki Yamada

Hideki Maeda

Takuya Ohara

Kaoru Arai

Masahiro Yokota

Takashi Kotanigawa

Takafumi Hamano

Takuya Oda

Takafumi Tanaka

Fumikazu Inuzuka

Masahito Tomizawa

Shokei Kobayashi

A transmission apparatus includes a control unit for carrying out processing to secure a resource for a standby system path in response to detection of a sign of failure in an active system path.

Transmission apparatus and transmission method

A transfer device includes a detection unit configured to detect a sign of a failure in a link between transfer devices, and a management unit configured to update a routing table to lower a priority of a path via the link when the sign of the failure is detected by the detection unit.

Failure transfer apparatus, failure transfer system, and failure transfer method

A transmission apparatus includes a first communication unit, a second communication unit, a detection unit, a control unit, and a selection unit. The first communication unit uses a first path for communication, when electric power is supplied. The second communication unit uses a second path for communication, when electric power is supplied. The detection unit detects a fault predictive sign. The control unit supplies no electric power to the second communication unit when the detection unit does not detect the fault predictive sign. The control unit starts supplying electric power to the second communication unit and performs normality confirmation of the second path when the detection unit detects the fault predictive sign, before switching from the first path to the second path. The selection unit selects and outputs, when the first communication unit and the second communication unit have received signals, either the signal received by the first communication unit or the signal received by the second communication unit.

In the optical transport system a transport frame generator divides a transport frame accommodating plural client signals into plural transmission signals. Subcarrier transmission units convert the signals into optical signals using different optical carriers and transmit the converted optical signals. Subcarrier reception units receive the transmitted optical signals and convert the optical signals into reception signals. A transport frame termination unit combines the reception signals to restore the transport frame. A time-demultiplexing processor time-demultiplexes the restored transport frame to be separated into the client signals. A time slot control unit determines a new time slot allocation when time-multiplexing the client signals in the transport frame and stops supply of electric power to a subcarrier transmission unit and a subcarrier reception unit that transmit and receive an optical signal to which the client signals are not allocated.

Optical transport system and resource optimization method

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.

Framer and framing method

A framer in a transmission device that allocates time slots of an optical channel to a logical path, divides client signals received via the logical path to the time slots allocated to the logical path, and transmits the client signals by a plurality of optical subcarriers using optical wavelengths correlated with the time slots includes: a time slot allocating unit configured to perform a process of reducing a transmission band of the logical path when some of the optical wavelengths are unavailable and changing the time slots allocated to the logical path depending on the reduced transmission band to avoid using the time slots corresponding to the unavailable optical wavelengths.

There is provided a tray which is connected to a plurality of transmitters that multicarrier-transmit a plurality of parallel signals by optical subcarriers. The framer selects time slots to be allocated to a path to be accommodated such that the number of optical subcarriers corresponding to the time slots satisfies a predetermined condition on the basis of empty time slots which are specified by path accommodation information indicating a correspondence between paths allocated to a client signal and time slots in a signal frame and the optical subcarriers corresponding to the empty time slots indicated by time slot information indicating a correspondence between the time slots and the optical subcarriers, and sets the selected time slot in the path accommodation information. The framer sets a client signal to the time slots on the basis of the path accommodation information.

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Yokosuka, Japan

Kengo Shintaku