Abstract: A time-point synchronization apparatus (10) includes a time-point management unit (144), a time-gap counter (145), and a time-gap calculation unit (142). The time-point management unit (144) manages an apparatus time point equivalent to a current time point. The time-gap counter (145) records a time gap which is a different between a time point indicated in reception information and the apparatus time point. When a frequency in the time-gap counter (145), corresponding to the time gap corresponding to a latest reception time point corresponding to latest reception information is treated as the highest among all of frequencies indicated in the time-gap counter (145), the time-gap calculation unit (142) synchronizes the apparatus time point to the latest reception time point.

Abstract: A reception unit (210) receives an addition requesting frame for requesting addition of a new flow. A first search unit (241) performs, using a network-information database (280), a first search for searching for a schedule and a path assignable to the new flow without the schedule and the path of each existing flow being changed, when the addition requesting frame is received. A second search unit (242) performs a second search for changing the schedule and the path of each existing flow and searching for the schedule and the path assignable to the new flow, using the network-information database, when the schedule and the path assignable to the new flow have not been found by the first search. A response unit (260) transmits an addition responding frame.

Abstract: A time-point synchronization apparatus (10) includes a time-point management unit (144), a time-gap counter (145), and a time-gap calculation unit (142). The time-point management unit (144) manages an apparatus time point equivalent to a current time point. The time-gap counter (145) records a time gap which is a different between a time point indicated in reception information and the apparatus time point. When a frequency in the time-gap counter (145), corresponding to the time gap corresponding to a latest reception time point corresponding to latest reception information is treated as the highest among all of frequencies indicated in the time-gap counter (145), the time-gap calculation unit (142) synchronizes the apparatus time point to the latest reception time point.

Abstract: A reception unit (210) receives an addition requesting frame for requesting addition of a new flow. A first search unit (241) performs, using a network-information database (280), a first search for searching for a schedule and a path assignable to the new flow without the schedule and the path of each existing flow being changed, when the addition requesting frame is received. A second search unit (242) performs a second search for changing the schedule and the path of each existing flow and searching for the schedule and the path assignable to the new flow, using the network-information database, when the schedule and the path assignable to the new flow have not been found by the first search. A response unit (260) transmits an addition responding frame.

Abstract: An information obtaining unit (53) of a monitoring apparatus (40) obtains from each node, topology map information created in each node by an exchange of information and sharing of information between nodes that belong to a ring network. The topology map information is information that indicates a connection relation between the nodes in the ring network. A topology comparison unit (54) of the monitoring apparatus (40) compares the topology map information obtained from each node by the information obtaining unit (53) with topology definition information retained in a memory (42) beforehand, and determines whether or not a configuration of the ring network is according to design. The topology definition information is information that defines the connection relation between the nodes in the ring network.

Abstract: An information obtaining unit (53) of a monitoring apparatus (40) obtains from each node, adjacent connection information (33) that is created in each node by an exchange of information and sharing of information between the nodes, and keeps the adjacent connection information (33) in a connection information file (38). The adjacent connection information (33) is information that indicates a connection relationship between the nodes. A topology comparison unit (54) of the monitoring apparatus (40) compares connection information included in the adjacent connection information (33) with topology definition information (59) retained in a topology definition file (58) beforehand, and determines whether or not a configuration of a ring network is according to design. The topology definition information (59) is information that defines the connection relationship between nodes in the ring network.

Abstract: Provided are a redundant route calculator that calculates, on the basis of first topology information on a network made up of a plurality of transfer devices, a plurality of shortest routes from a first transfer device to a second transfer device among the plurality of transfer devices, and generates redundant route information; a forwarding database that stores the redundant route information; and a single point-of-failure detector that detects a single point of failure on the basis of the redundant route information and generates second topology information obtained by removing the single point of failure from the first topology information. On the basis of the second topology information, the redundant route calculator calculates an additional route candidate from the first transfer device to the second transfer device. The single point-of-failure detector decides the additional route to register in the forwarding database.

Abstract: A transfer device according to the present invention is a switching device that is one of transfer devices forming a network, and includes: a link state database that holds topology information of the network, and priority of the transfer device and priorities of other transfer devices forming the network to be used in path computation; a shortest path calculating unit that calculates a shortest path from a first switching device to a second switching device among the transfer devices forming the network on the basis of the topology information; and a priority adjusting unit that adjusts the priority of the transfer device on the basis of the shortest path calculated by the shortest path calculating unit and the priority of the transfer device and the priorities of the other transfer devices, wherein the priority adjusting unit adjusts the priority of the transfer device so that the number of overlaps with priority of another transfer device that is included with the transfer device in a shortest path from on

Abstract: An information obtaining unit (53) of a monitoring apparatus (40) obtains from each node, topology map information created in each node by an exchange of information and sharing of information between nodes that belong to a ring network. The topology map information is information that indicates a connection relation between the nodes in the ring network. A topology comparison unit (54) of the monitoring apparatus (40) compares the topology map information obtained from each node by the information obtaining unit (53) with topology definition information retained in a memory (42) beforehand, and determines whether or not a configuration of the ring network is according to design. The topology definition information is information that defines the connection relation between the nodes in the ring network.

Abstract: A transfer device according to the present invention is a switching device that is one of transfer devices forming a network, and includes: a link state database that holds topology information of the network, and priority of the transfer device and priorities of other transfer devices forming the network to be used in path computation; a shortest path calculating unit that calculates a shortest path from a first switching device to a second switching device among the transfer devices forming the network on the basis of the topology information; and a priority adjusting unit that adjusts the priority of the transfer device on the basis of the shortest path calculated by the shortest path calculating unit and the priority of the transfer device and the priorities of the other transfer devices, wherein the priority adjusting unit adjusts the priority of the transfer device so that the number of overlaps with priority of another transfer device that is included with the transfer device in a shortest path from on

Abstract: Provided are a redundant route calculator that calculates, on the basis of first topology information on a network made up of a plurality of transfer devices, a plurality of shortest routes from a first transfer device to a second transfer device among the plurality of transfer devices, and generates redundant route information; a forwarding database that stores the redundant route information; and a single point-of-failure detector that detects a single point of failure on the basis of the redundant route information and generates second topology information obtained by removing the single point of failure from the first topology information. On the basis of the second topology information, the redundant route calculator calculates an additional route candidate from the first transfer device to the second transfer device. The single point-of-failure detector decides the additional route to register in the forwarding database.

Abstract: A time synchronization method for a communication system configured to perform protection switching, the communication system including a first network in which a master station and a slave station are connected via plural physical lines including a working line and a backup line and a second network connected to the slave station, the method including a time synchronization in which the slave station executes, when not detecting a communication failure of a downlink signal transmitted from the master station, synchronization processing for synchronizing, based on a clock of the slave station and timing information, time information transmitted to the second network with time information included in a time synchronization command and suppresses, when detecting a communication failure or receiving a switching notification from the master station apparatus, a synchronization error due to a difference between the clock of the slave station and the timing information.

Abstract: A relay device that relays communication between a low-speed communication device performing uplink 1 G transfer and a high-speed communication device performing uplink 10 G transfer and a station-side optical communication device, wherein the relay device includes a low-speed reception unit that converts an optical signal received from the low-speed communication device to an electric signal, a buffer that buffers the electric signal, and a high-speed transmission unit that transmits, to the station-side optical communication device, a bandwidth allocation request requesting bandwidth allocation for communication from its own unit to the station-side optical communication device, and within a transmission permitted time period allocated by the station-side optical communication device, reads an electric signal stored in the buffer, converts the electric signal to an optical signal having a communication speed of 10 G, and transmits the optical signal.

Abstract: An optical line terminal performs transmission to optical network units using a light signal having a wavelength different for each of systems, allocates communication time to data, which is transmitted from the optical network units, in a time division manner for each of the systems, selects, for each of the optical network units, a system for performing data transmission, and transmits the data using a wavelength corresponding to the selected system. The optical network unit includes: ith blocking filter that removes a component other than a component in a predetermined wavelength band, which is set to correspond to an ith system, from a received light signal; and ith PON processing unit that applies termination processing to signals and transmitting the data based on an allocation result of the optical line terminal. The PON system includes n optical network units corresponding to i=1 to i=n.

Abstract: A time synchronization method for a communication system configured to perform protection switching, the communication system including a first network in which a master station and a slave station are connected via plural physical lines including a working line and a backup line and a second network connected to the slave station, the method including a time synchronization in which the slave station executes, when not detecting a communication failure of a downlink signal transmitted from the master station, synchronization processing for synchronizing, based on a clock of the slave station and timing information, time information transmitted to the second network with time information included in a time synchronization command and suppresses, when detecting a communication failure or receiving a switching notification from the master station apparatus, a synchronization error due to a difference between the clock of the slave station and the timing information.

Abstract: A relay device that relays communication between a low-speed communication device performing uplink 1 G transfer and a high-speed communication device performing uplink 10 G transfer and a station-side optical communication device, wherein the relay device includes a low-speed reception unit that converts an optical signal received from the low-speed communication device to an electric signal, a buffer that buffers the electric signal, and a high-speed transmission unit that transmits, to the station-side optical communication device, a bandwidth allocation request requesting bandwidth allocation for communication from its own unit to the station-side optical communication device, and within a transmission permitted time period allocated by the station-side optical communication device, reads an electric signal stored in the buffer, converts the electric signal to an optical signal having a communication speed of 10 G, and transmits the optical signal.

Abstract: An OLT includes an upper-layer processing unit that receives a transmission request for notifying a data amount transmitted from an ONU and applies predetermined upper-layer processing to data received from the ONU. The OLT includes a band-allocation-information managing unit that instructs, based on the transmission request, when determining that a free period, which is a period in which a band is not allocated to data transmission from the ONU, equal to or larger than a predetermined band threshold is present, the upper-layer processing unit to shift a power saving state. The upper-layer processing unit shifts to the power saving state based on the instruction.

Abstract: In a PON system including a high-speed optical signal of a high transmission speed and a low-speed optical signal the speed of which is lower than that of the high-speed optical signal, the PON system employing TDMA system for upward signal transmission, an OLT controls transmission and reception of the low-speed optical signal and the high-speed optical signal and allocates a grant to a slave station unit connected to the OLT.

Abstract: An optical line terminal performs transmission to optical network units using a light signal having a wavelength different for each of systems, allocates communication time to data, which is transmitted from the optical network units, in a time division manner for each of the systems, selects, for each of the optical network units, a system for performing data transmission, and transmits the data using a wavelength corresponding to the selected system. The optical network unit includes: ith blocking filter that removes a component other than a component in a predetermined wavelength band, which is set to correspond to an ith system, from a received light signal; and ith PON processing unit that applies termination processing to signals and transmitting the data based on an allocation result of the optical line terminal. The PON system includes n optical network units corresponding to i=1 to i=n.

Abstract: A bit identification circuit includes a multiphase clock generating unit that outputs multiphase clocks, a phase selecting unit that samples the input data signals using the multiphase clocks and selects a sampled result out of a plurality of sampled results, a correcting unit that thins a part of bits of the sampled result selected by the phase selecting unit based on the difference in bit rates, and a rate selecting unit that selects based on a selection signal for identifying the data signals and outputs one of an output of the correcting unit and an output of the phase selecting unit.