Hitachi, Ltd.

Hitachi Communication Technologies, Ltd.

Tetsuya Uda

Hiroyuki Nakano

Hiroshi Masuda

Hirofumi Nakano

Yasuyuki Fukashiro

Satoshi Asamizu

Yoshimasa Kusano

Yasuhiro Uchiyama

Tooru Hirai

Eita Miyasaka

Kenta Noda

Masayuki Takase

Shigenori Hayase

Kenji Fujihira

Koji Takatori

Hidemasa Narita

Takeshi Nakada

Masafumi Kamakura

Shigehiro Takashima

Ryoichi Miyake

Hiroshi Takeuchi

Shinya Sasaki

Nobuhiko Kikuchi

Takashi Mori

Takayuki Kanno

Riu Hirai

Kento Iizawa

Elichirou Takizawa

Eiichirou Takizawa

Provided is a communication device including a plurality of physical ports, the communication device holding information for associating each of at least one logical port and at least two physical ports, the communication device being configured to: identify, when any one of the plurality of physical ports receives data including user data, one of the at least one logical port as an output destination of the data based on destination information included in the received data; select, based on the data, one of the at least two physical ports associated with the identified logical port as an destination of the data; generate coupling check data relating to one of the plurality of physical ports; transmit the coupling check data from the one of the plurality of physical ports; and transmit data including the user data from the physical port selected by a first processing unit as the output destination.

Communication device and method of controlling the same

In an example of the invention, network devices are classified into areas. Each of the areas includes edge nodes. A network management apparatus retains fault information including values each indicating whether or not a fault has occurred in each of the areas, retains detour path information including values indicating edge nodes, values indicating alternative areas to the areas and priorities assigned to the alternative areas, identifies, when determined that a fault has occurred in a first area based on the fault information, an alternative area to the first area based on the detour path information, determines, when determined that the fault has not occurred in the identified alternative area, the identified alternative area as a second area through which the active path passes, determines two edge nodes included in the second area, and detect network devices through which the active path passes between the two edge nodes.

Communication system, communication method and network management apparatus

An OADM device without a transponder unit does not mount the transponder in charge of separating a fault between the OADM device and an external device and is difficult to perform fault separation and to identify a fault interval. To solve this problem, for the OADM device without the transponder unit, the optical loop back function is provided by using such a switch as, for example, 2&#xd7;2 optical switch. By identifying a fault developing interval by the use of the optical loop back function, fault separation at the time of occurrence of a fault can be facilitated.

Optical transmission system and optical transmission method

There arises a problem that power consumption increases along with an increasing throughout of an FEC function effective in speeding up of a transmission speed. FEC function information necessary for a system is prepared, and multiple FEC functions are properly used according to a selected transmission line, etc.

Optical communication card and optical transmission device

Multiplexing-technology based large-capacity transmission requires the installation of many types of interface card. In addition, supporting a redundant configuration for preventing data communication from being interrupted requires the devices and cards more than double those required for the production system. An optical communication card includes multiple optical signal transmission/reception units, main signal processing units corresponding to the optical signal transmission/reception units and required for a multiplexed system, and a connection selection unit that can switch among multiple optical transmission lines, and each of the main signal processing units includes multiple function units and a function selection unit.

Optical communication card and communication device

Bending of an optical fiber where a heat may be generated by a high output power can be detected without using a dedicated light source. An optical communication module that outputs a continuous wave light generated by at least one light source to an optical fiber transmission line, includes: (1) a loss measurement unit that measures a loss of an amplified spontaneous emission generated by allowing the continuous wave light output from the light source to create stimulated Raman scattering in the optical fiber transmission line; (2) a fiber abnormality analyzer that detects the abnormal state of the optical fiber transmission line on the basis of loss information on the ASE measured by the loss measurement unit; and (3) a light source controller that controls a supply state of the continuous wave light from the light source on the basis of the detection of the fiber abnormality analyzer.

Optical communication module and optical fiber communication system

An optical transmission apparatus is arranged by: means for demultiplexing monitoring light for received wavelength-multiplexed signal light so as to detect optical intensity of the monitoring light; means for detecting optical intensity of wavelength-multiplexed signal light after the monitoring light has been demultiplexed therefrom; a gain controlling type optical amplifier for amplifying the wavelength-multiplexed signal light; an optical attenuating unit for adjusting optical intensity of the amplified wavelength-multiplexed signal light; and a monitoring control unit for controlling the gain controlling type optical amplifier in such a manner that the gain of the optical amplifier becomes constant, and for controlling an attenuating amount of the optical attenuating unit in such a manner that the optical intensity of the wavelength-multiplexed signal light becomes a predetermined target value.

Optical transmission apparatus

An optical transmission apparatus comprising a first detector for detecting the power of the supervisory signal light separated from received wavelength-division multiplexed signal lights; a second detector for detecting the power of the wavelength-division multiplexed signal lights after the separation of the supervisory signal light; a gain-controlled type optical amplifier for amplifying the wavelength-division multiplexed signal lights; an optical attenuator coupled to the amplifier; and a control unit for controlling the optical amplifier and the optical attenuator so as to keep the output level of the wavelength-division multiplexed signal lights to a predetermined target value, wherein the control unit restrains automatic output level control by the optical attenuator when the supervisory signal light power fluctuates within its permissible range and fluctuations in the signal light power have deviated from its permissible range.

Optical transmission apparatus and control method therefor

Optical transmision apparatus and control method therefor

Disclosed is an optical transmission device with a simple configuration that can attenuate an input optical power only when it is necessary so that it falls within a predetermined range, and can suppress insertion loss when it is unnecessary. A variable optical attenuator is configured pluggable. A pluggable variable optical attenuator is equipped with an optical connector that is an interface of an optical signal and an electrical signal connector for receiving an electrical signal that specifies the amount of control used for feedback-controlling the attenuation, and controls the attenuation depending on the input optical power of the optical transmission board. Moreover, an optical through that has the same shape as the variable optical attenuator being configured pluggable and that is configured pluggable is prepared.

Optical transmission device equipped with pluggable variable optical attenuator

In the WDM systems, the OSNR and the signal loss among the optical signals are substantially minimized at the receiving terminal to combat the SRS effects. An equal amount of the signal loss is expected for every span in the transmission path so that the optical amplifier gain tilt is not affected among a number of wavelength frequencies in the optical signal. This is accomplished by controlling the amplification process according to a feedback from the monitoring units for monitoring the optical signal.

Optical transmission system for substantially equalizing the output signal level among frequency bands and substantially lowering the signal-to-noise ratio

An optical switch having plural input terminals and plural output terminal, plural dispersion compensators, and a controller for monitoring the change-over state of the optical switch and the dispersion compensation quantities of the plural dispersion compensators and controlling the setting of the optical switch are provided. In response to a request for setting dispersion compensation, the optical switch is set according to the dispersion compensation quantity of each dispersion compensator and the change-over state of the optical switch.

Variable dispersion compensation equipment, optical transmission system using it and method of setting dispersion compensation quantity

A dispersion compensating fiber whose chromatic dispersion is positive and a negative dispersion compensating fiber whose chromatic dispersion is negative are prepared, and division-multiplexed optical signals, after being guided to either dispersion compensating fiber to once shift the whole wavelength band to positivity or negativity, are subjected to fine adjustment with a dispersion compensating fiber of a reverse sign.

Dispersion compensation device and dispersion compensation method

Optical signal transmission is improved by reducing the variance in light output level and OSNR by adjusting optical signal intensity and gain tilt, taking SRS influence into consideration.

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Yokohama, Japan

Tetsuya Uda