Abstract: There is provided an optical transmission device including a light source configured to generate light used for coherent detection processing of reception light; a monitor configured to monitor a frequency offset between the reception light having a plurality of protection wavelengths and the light generated by the light source, based on a signal obtained by the coherent detection processing of the reception light having the plurality of protection wavelengths available for a work wavelength by the light generated by the light source; and a controller configured to select a protection wavelength to be switched to the work wavelength among the plurality of protection wavelengths, based on the frequency offset monitored by the monitor.

Abstract: There is provided an optical transmission device including a light source configured to generate light used for coherent detection processing of reception light; a monitor configured to monitor a frequency offset between the reception light having a plurality of protection wavelengths and the light generated by the light source, based on a signal obtained by the coherent detection processing of the reception light having the plurality of protection wavelengths available for a work wavelength by the light generated by the light source; and a controller configured to select a protection wavelength to be switched to the work wavelength among the plurality of protection wavelengths, based on the frequency offset monitored by the monitor.

Abstract: A transmission apparatus includes a network-side interface unit configured to receive a signal transmission frame into which a client signal is arranged from each of a working line and a protection line of a network, and extract the client signal from the received signal transmission frame, a client-side interface unit configured to transmit the extracted client signal to a client transmission path by using a generated clock, based on frequency adjustment information of the client signal included in the signal transmission frame, a protection-line-side memory configured to store the frequency adjustment information of the client signal included in the signal transmission frame received from the protection line, and a switch controller configured to control to generate a clock by using the frequency adjustment information of the client signal stored in the protection-line-side memory when the signal transmission frame fails to be received from the working line.

Abstract: A transmission device includes a receiver receiving a signal transmission frame from a network, where a client signal is mapped to the signal transmission frame; a separator separating the client signal from the signal transmission frame; a phase synchronizer generating a clock based on a frequency adjustment information set of the client information included in the signal transmission frame; a transmitter transmitting the client signal to a client transmission path by using the clock generated by the phase synchronizer; a memory storing the frequency adjustment information set included in the signal transmission frame in response to receiving the signal transmission frame from the network by the receiver; and a switch controller causing the phase synchronizer to generate a clock based on the frequency adjustment information set stored in the memory in response to not receiving the signal transmission frame from the network by the receiver.

Abstract: A transmission apparatus includes a network-side interface unit configured to receive a signal transmission frame into which a client signal is arranged from each of a working line and a protection line of a network, and extract the client signal from the received signal transmission frame, a client-side interface unit configured to transmit the extracted client signal to a client transmission path by using a generated clock, based on frequency adjustment information of the client signal included in the signal transmission frame, a protection-line-side memory configured to store the frequency adjustment information of the client signal included in the signal transmission frame received from the protection line, and a switch controller configured to control to generate a clock by using the frequency adjustment information of the client signal stored in the protection-line-side memory when the signal transmission frame fails to be received from the working line.

Abstract: A transmission device includes a receiver receiving a signal transmission frame from a network, where a client signal is mapped to the signal transmission frame; a separator separating the client signal from the signal transmission frame; a phase synchronizer generating a clock based on a frequency adjustment information set of the client information included in the signal transmission frame; a transmitter transmitting the client signal to a client transmission path by using the clock generated by the phase synchronizer; a memory storing the frequency adjustment information set included in the signal transmission frame in response to receiving the signal transmission frame from the network by the receiver; and a switch controller causing the phase synchronizer to generate a clock based on the frequency adjustment information set stored in the memory in response to not receiving the signal transmission frame from the network by the receiver.

Abstract: A transmission device capable of detecting and discarding duplicate data transmitted over Work and Protection paths of a ring network. An add/drop multiplexer adds/drops and cross-connects signals. When an FS-R control signal, for example, is received, a bridge distributes the signal output from the add/drop multiplexer to the Work and Protection routes of the ring network. When the signal distribution is executed by the bridge, a discard information inserter inserts discard information into the signal output to the Work route by the bridge. A discard information detector determines whether or not the discard information is included in the signal dropped by the add/drop multiplexer. A signal discarder discards the dropped signal, depending on whether the discard information is detected by the discard information detector.

Abstract: A transmitting apparatus connects a first network that includes a plurality of channels each of which having a preset priority and a predetermined bandwidth speed and a second network. A bandwidth-speed adjusting unit retrieves, when a channel speed of the second network changes, the changed channel speed, adjusts the bandwidth speed in such a manner that a sum of the bandwidth speeds of the channels of the first network does is below the changed channel speed and a bandwidth speed of a high-priority channel is not decreased from an inherent bandwidth speed, and resets the adjusted bandwidth speed on each of the channels of the first network.

Abstract: A transmission control apparatus detects worsening of an environmental condition of a transmission line for accommodating a plurality of circuits, and detects recovery of the environmental condition of the transmission line from the worsening. A first controller alters a transmission rate of data that is transmitted on the transmission line, from a first transmission rate to a second transmission rate, when the worsening of the environmental condition is detected, and which alters the transmission rate when the recovery of the environmental condition is detected. A second controller narrows down a bandwidth of a circuit of a lower priority when the bandwidth of any of the circuits having been accommodated by the transmission line becomes unaccommodatable because of the alteration of the transmission rate to the second transmission rate.

Abstract: A network device provided with an Ethernet interface for interconnecting with another network device by auto negotiation, the network device comprising a link establishing function unit compulsorily establishing a link with the other network device and an on/off setting function unit setting the function of the link establishing function unit on or off and the link establishing function unit being comprised of a data transmission suppressing unit for suppressing the transmission of user data to the other network device until the sequence based on the auto negotiation is finished, whereby the problem of connectivity where the sequence of the auto negotiation repeats and no link can be established is solved.

Abstract: A transmission device capable of detecting and discarding duplicate data transmitted over Work and Protection paths of a ring network. An add/drop multiplexer adds/drops and cross-connects signals. When an FS-R control signal, for example, is received, a bridge distributes the signal output from the add/drop multiplexer to the Work and Protection routes of the ring network. When the signal distribution is executed by the bridge, a discard information inserter inserts discard information into the signal output to the Work route by the bridge. A discard information detector determines whether or not the discard information is included in the signal dropped by the add/drop multiplexer. A signal discarder discards the dropped signal, depending on whether the discard information is detected by the discard information detector.

Abstract: A transmitting apparatus connects a first network that includes a plurality of channels each of which having a preset priority and a predetermined bandwidth speed and a second network. A bandwidth-speed adjusting unit retrieves, when a channel speed of the second network changes, the changed channel speed, adjusts the bandwidth speed in such a manner that a sum of the bandwidth speeds of the channels of the first network does is below the changed channel speed and a bandwidth speed of a high-priority channel is not decreased from an inherent bandwidth speed, and resets the adjusted bandwidth speed on each of the channels of the first network.

Abstract: A communication system capable of performing efficient Wavelength Division Multiplexing (WDM) transmission by flexibly handling connection services. A Bit Error Rate (BER) measurement unit measures BER of individual optical signals with different wavelengths. A BER transmission unit transmits BER information to the sending end. A wavelength assignment unit assigns each wavelength to at least one of high Quality-of-Service (QoS) communication and low QoS communication. A wavelength-assignment exchanging unit identifies low quality wavelengths with high BERs being used for the high QoS communication, and unless the low quality wavelengths being used for the high QoS communication outnumber the high quality wavelengths with low BERs being used for the low QoS communication, it exchanges the low quality wavelengths and an equal number of the high quality wavelengths. An optical signal transmission unit multiplexes the wavelengths to transmit the optical signals.

Abstract: Switching control apparatus and method between LAN interface terminals that are accommodated in a ring network including a synchronous network. A transmission system which is capable of performing high-speed redundant switching in the event of a failure of a transmission path regardless of the number of rings in a multi-ring configuration includes a first transmission apparatus connected to a first terminal has a LAN interface for sending and receiving an ordinary packet, and a synchronous frame interface for sending and receiving a synchronous frame to and from a second transmission path, a link detector for detecting a physical link failure of the first transmission path. The system also includes a second transmission apparatus connected to the first transmission apparatus and also connected to a second terminal. The second transmission apparatus has a synchronous frame interface for sending and receiving a synchronous frame.

Abstract: A network device provided with an Ethernet interface for interconnecting with another network device by auto negotiation, the network device comprising a link establishing function unit compulsorily establishing a link with the other network device and an on/off setting function unit setting the function of the link establishing function unit on or off and the link establishing function unit being comprised of a data transmission suppressing unit for suppressing the transmission of user data to the other network device until the sequence based on the auto negotiation is finished, whereby the problem of connectivity where the sequence of the auto negotiation repeats and no link can be established is solved.

Abstract: A communication system capable of performing efficient Wavelength Division Multiplexing (WDM) transmission by flexibly handling connection services. A Bit Error Rate (BER) measurement unit measures BER of individual optical signals with different wavelengths. A BER transmission unit transmits BER information to the sending end. A wavelength assignment unit assigns each wavelength to at least one of high Quality-of-Service (QoS) communication and low QoS communication. A wavelength-assignment exchanging unit identifies low quality wavelengths with high BERs being used for the high QoS communication, and unless the low quality wavelengths being used for the high QoS communication outnumber the high quality wavelengths with low BERs being used for the low QQS communication, it exchanges the low quality wavelengths and an equal number of the high quality wavelengths. An optical signal transmission unit multiplexes the wavelengths to transmit the optical signals.

Abstract: Disclosed is a wavelength division multiplexing apparatus comprising a plurality of variable attenuators (12) which respectively attenuate a plurality of optical signals of different wavelengths with variable amounts of attenuation, an optical combiner (14) which combines optical outputs of the plurality of variable attenuators, and an optical amplifier (16) which optically amplifies an optical output of the optical combiner, wherein in order to prevent light leaking from an unused wavelength from affecting the optical amplification of wavelengths in use, an optical switch (46) is provided in front of each variable attenuator and, for the unused wavelength, the optical switch is switched to the attenuation film side to secure a sufficient amount of attenuation.

Abstract: Disclosed is a wavelength division multiplexing apparatus comprising a plurality of variable attenuators (12) which respectively attenuate a plurality of optical signals of different wavelengths with variable amounts of attenuation, an optical combiner (14) which combines optical outputs of the plurality of variable attenuators, and an optical amplifier (16) which optically amplifies an optical output of the optical combiner, wherein in order to prevent light leaking from an unused wavelength from affecting the optical amplification of wavelengths in use, an optical switch (46) is provided in front of each variable attenuator and, for the unused wavelength, the optical switch is switched to the attenuation film side to secure a sufficient amount of attenuation.

Abstract: An optical attenuation device to attenuate the intensity of incident light, comprising an optical attenuation unit including at least two different type magneto-optical optical attenuation elements coupled in a cascade together.