Abstract: An optical path cross-connect device includes a wavelength branching unit, an intra office signal input unit, “m” pieces of routing units, a wavelength combining unit and an intra-office signal output unit. The routing units input thereinto an optical signal outputted from either of the wavelength branching unit and the intra-office signal input unit via a first optical path group, and convert an input optical signal into a predetermined wavelength to thereby output a wavelength-converted optical signal to a second optical path group. The “m” (symbol being an integer and also being larger than 1)” pieces of routing units are subdivided into units of at least “n (symbol “n” being an integer and also being larger than 1)” wavelengths, as wavelength ranges to be processed by the respective routing unit are different from each other.

Abstract: Each piece of WDM light transmitted via the first and second line is demultiplexed for each wavelength by the first and second optical demultiplexer, and is selected by n optical selectors. Each selected optical signal is split by n optical splitters and is input to one set of optical switches. Each one of optical signals from the set of optical switches is selected by n optical selectors. Furthermore, each selected optical signal is regenerated by n wavelength converters. Each regenerated optical signal is split by n optical splitters, and is multiplexed by the first and second optical multiplexers.

Abstract: A frame forwarding device for forwarding a frame in a network of a datalink layer includes: an acquisition unit for acquiring a status of an adjacent port from an adjacent device having the adjacent port accommodating a link accommodated in a port of a self-device; a determination unit for determining whether or not a frame loop is generated based on an inconsistency between a status of the port of the self-device and the status of the adjacent port; and a blocking unit for blocking the port of the self-device when determined that the loop is generated.

Abstract: An optical path cross-connect device includes a wavelength branching unit, an intra office signal input unit, “m” pieces of routing units, a wavelength combining unit and an intra-office signal output unit. The routing units input there into an optical signal outputted from either of the wavelength branching unit and the intra-office signal input unit via a first optical path group, and convert an input optical signal into a predetermined wavelength to thereby output a wavelength-converted optical signal to a second optical path group. The “m” (symbol being an integer and also being larger than 1)” pieces of routing units are subdivided into units of at least “n (symbol “n” being an integer and also being larger than 1)” wavelengths, as wavelength ranges to be processed by the respective routing unit are different from each other.

Abstract: An optical XC apparatus is provided that is advantageous for the construction of a large-scale WDM optical network, and that minimizes signal loss variations between routes. The optical XC apparatus comprises four switch modules SWM1 to SWM4 each of which has, at each crosspoint in a matrix switch, a two-input, two-output wavelength routing element constructed from an acousto-optic tunable filter, wherein the input ports of the SWM1 and SWM3 are allocated as the input ports of the apparatus, the output ports of the SWM2 and SWM4 are allocated as the output ports of the apparatus, and the output ports and auxiliary output ports of SWM1 and SWM3 are connected to the input ports and auxiliary input ports of SWM2 and SWM4, to construct the optical XC apparatus.

Abstract: A loop frame detecting devise includes a frame receiving and transmitting unit and a loop detecting unit. The frame receiving and transmitting unit receives and transmits the Layer 2 frame. The loop detecting unit monitors contents of the frame that is received or to be transmitted by the frame receiving and transmitting unit, determines whether the frame is a loop frame that circulates in the Layer 2 network, detects the loop frame, and minimizes a loop failure.

Abstract: An abnormal traffic eliminating apparatus eliminates an abnormal traffic that is generated in a network through which frames including a MAC header part, an IP header part and an IP datagram part are transmitted. The apparatus is provided with a write part for writing an FCS field of an MAC frame that is received by a plurality of ports to a search engine part, and a loop monitoring and detecting part counting a number of received MAC frames having identical FCS values and judging that the network is in a loop state if the number of received MAC frames having the identical FCS values and received within a predetermined time exceeds a preset threshold value.

Abstract: A layer 2 loop detection apparatus includes a unit recognizing a topology of an L2 network at normal time by collecting MIB information including information concerning ports of a plurality of L2 switches from the plurality of L2 switches through SNMP communication; a unit discriminating, based on a topology recognition processing, a blocking port for traffic blocking and a disable port under a port disable state each set under a Spanning Tree Protocol (STP); a unit setting each of the blocking port and the disable port as a monitoring point and periodically monitoring a state thereof; and a unit performing detection of an L2 loop by re-collecting a part of the MIB information from the plurality of L2 switches through SNMP communication and re-recognizing the topology of the L2 network, the detection of the L2 loop detection being triggered by a change of a state of one of the blocking port and the disable port.

Abstract: In an optical cross-connect device for constructing a large scale optical network that supports an increase in the number of wavelengths, and an optical network using this optical cross-connect device, the optical cross-connect device comprises: a combination of any two of “a” units of wave multiplexers for multiplexing “n” waves of light signals directly received from an intra-office device to be transferred to a same destination, “L?a” threads of transmission lines each for transmitting an n-wave-multiplexed light signal, and “a” units of wave demultiplexers for demultiplexing the n-wave-multiplexed light signals bound for the same destination; and an L*L light switch for selecting the combination for transmitting the light signals to the same destination. Furthermore, a protective transmission line is provided, and a protective-signal light switch for selecting a combination of the protective transmission line, the wave multiplexer, and the wave demultiplexer is provided.

Abstract: An optical path cross-connect device includes a wavelength branching unit, an intra office signal input unit, “m” pieces of routing units, a wavelength combining unit and an intra-office signal output unit. The routing units input thereinto an optical signal outputted from either of the wavelength branching unit and the intra-office signal input unit via a first optical path group, and convert an input optical signal into a predetermined wavelength to thereby output a wavelength-converted optical signal to a second optical path group. The “m” (symbol being an integer and also being larger than 1)” pieces of routing units are subdivided into units of at least “n (symbol “n” being an integer and also being larger than 1)” wavelengths, as wavelength ranges to be processed by the respective routing unit are different from each other.

Abstract: An optical switch has first to fourth optical matrix switches in each of which a plurality of 2-input/2-output optical switch elements are arranged in a matrix to form a plurality of input ports, a plurality of auxiliary input ports, a plurality of output ports, and a plurality of auxiliary output ports. The auxiliary output ports in the first optical matrix switch are connected to the respective input ports in the third optical matrix switch, the output ports in the second optical matrix switch are connected to the respective auxiliary input ports in the third optical matrix switch, the output ports in the first optical matrix switch are connected to the respective auxiliary input ports in the fourth optical matrix switch, and the auxiliary output ports in the second optical matrix switch are connected to the respective input ports in the fourth optical matrix switch.

Abstract: The present invention is directed to an optical space switch accommodating a plurality of input light paths and output light paths. The optical space switch comprises a plurality of polarization control optical switches, each consisting essentially of: polarization control means having elements, one for each input light path, for rotating through 90° the polarizing direction of light information incident from each input light path or otherwise retaining the polarizing direction thereof for output; and a light path routing element for routing the light path for the light information output from the polarization control means in accordance with the polarizing direction of the light information. These polarization control optical switches are arranged in a matrix pattern or coupled in cascade to implement a polarization control optical space switch.

Abstract: Disclosed herein is an optical cross-connect device including first wavelength demultiplexing sections each for demultiplexing WDM (wavelength division multiplexed) signal light into a plurality of optical signals, wavelength group generating sections each for receiving the optical signals from each first wavelength demultiplexing section to generate wavelength groups, first wavelength multiplexing sections each for receiving each wavelength group from each wavelength group generating section to output a WDM wavelength group, a routing section for routing the input WDM wavelength groups, second wavelength demultiplexing sections each for receiving each WDM wavelength group from the routing section to output a wavelength group having a plurality of wavelengths, wavelength converting sections each for performing wavelength conversion of each optical signal of the wavelength group output from each second wavelength demultiplexing section, and second wavelength multiplexing sections each for wavelength division m

Abstract: The present invention relates to a technology of an IP node for transferring IP packets accommodated in a wavelength division multiplexing optical signal.

Abstract: In an optical cross-connect device for constructing a large scale optical network that supports an increase in the number of wavelengths, and an optical network using this optical cross-connect device, the optical cross-connect device comprises: a combination of any two of “a” units of wave multiplexers for multiplexing “n” waves of light signals directly received from an intra-office device to be transferred to a same destination, “L−a” threads of transmission lines each for transmitting an n-wave-multiplexed light signal, and “a” units of wave demultiplexers for demultiplexing the n-wave-multiplexed light signals bound for the same destination; and an L*L light switch for selecting the combination for transmitting the light signals to the same destination.

Abstract: The present invention aims at providing an optical switch changeover controlling method, an optical node device and an optical switch system, capable of avoiding an interruption in an optical output power when changing over an optical path making use of a spatial optical switch arranged with a plurality of optical switch elements. To this end, the optical switch changeover controlling method according to the present invention enables an uninterrupted changeover of an optical path by conducting a reconnection of the optical path after establishing a state where the optical path before the changeover and the optical path after the changeover are simultaneously set concerning the spatial optical switch within the optical node device, when conducting a changeover of the optical path so as to transmit a client optical signal having been transmitted through a working ray path to a protective ray path such as in a case that a fault occurs in the working ray path.

Abstract: Each piece of WDM light transmitted via the first and second line is demultiplexed for each wavelength by the first and second optical demultiplexer, and is selected by n optical selectors. Each selected optical signal is split by n optical splitters and is input to one set of optical switches. Each one of optical signals from the set of optical switches is selected by n optical selectors. Furthermore, each selected optical signal is regenerated by n wavelength converters. Each regenerated optical signal is split by n optical splitters, and is multiplexed by the first and second optical multiplexers.

Abstract: In an optical cross-connect device for constructing a large scale optical network that supports an increase in the number of wavelengths, and an optical network using this optical cross-connect device, the optical cross-connect device comprises: a combination of any two of “a” units of wave multiplexers for multiplexing “n” waves of light signals directly received from an intra-office device to be transferred to a same destination, “L−a” threads of transmission lines each for transmitting an n-wave-multiplexed light signal, and “a” units of wave demultiplexers for demultiplexing the n-wave-multiplexed light signals bound for the same destination; and an L*L light switch for selecting the combination for transmitting the light signals to the same destination.

Abstract: In addition to the configuration of a conventional optical XC node, a former-stage regenerator for converting optical signals to electrical signals and regenerating optical signals again is provided at an output stage of a demultiplexer and at the input stage of an optical switch unit. Since the regenerator has a 3R function, the regenerator compensates for the influence of the noise and crosstalk generated during propagation in the transmission line, and improves the S/N ratio of the optical signals. Since the optical signals with S/N ratios improved in this way are inputted to the optical switch unit, it is sufficient only if a latter-stage regenerator compensates for the S/N ratio degradation generated in the optical switch unit, and thereby the error rate characteristic of the optical signals can be improved.

Abstract: A data distribution system capable of suppressing a fall of the efficiency of operation of a network due to repeated data retransmission in the network when distributing a large volume of data from a data distribution server on a data provider side to a data receiver side access server via the network. This data distribution system is comprised by a data distribution server, an access server for transferring intended data to each user, and a network cache apparatus provided in the network and having a cache function unit for temporarily storing the data from the data distribution server and an exchange function unit for routing the stored data to the access server corresponding to the destination user.