Abstract: A relay device includes a plurality of physical ports (111-1 to 111-N) that receive frames, and a layer-2 protocol processing unit (113) that transfers the frame received by one of the physical ports (111-1 to 111-N) from at least one of the physical ports (111-1 to 111-N). The layer-2 protocol processing unit (113) has a filtering function for blocking frames other than a clock-time synchronization frame during transfer involving a port selected from the plurality of physical ports (111-1 to 111-N) as a port that relays only the clock-time synchronization frame used for synchronizing clock time.

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: The conventional relay device has a problem that a traffic load on a communication device is large when an output port of a frame including a destination address, which an address table has not learned yet, is a port connected to a branch circuit, since flooding is performed on all ports except for a port that has received the frame. A relay device (21) is provided with a destination determination unit (41) to transfer, when a time clocked by a timer unit (40) to start clocking is within a set time, a frame to ports (511 and 512) connected to trunk circuits (61 and 64), and when the time clocked by the timer unit (40) exceeds the set time, to transfer the frame to the ports (511 and 512) connected to the trunk circuits (61 and 64) and a port (513) connected to a branch circuit (65), in a case wherein it is impossible for a search unit (43) to obtain from a first storage unit (33) a port number corresponding to a destination address included in the frame received, and the first storage unit (33) is cleared.

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 relay device includes a plurality of physical ports (111-1 to 111-N) that receive frames, and a layer-2 protocol processing unit (113) that transfers the frame received by one of the physical ports (111-1 to 111-N) from at least one of the physical ports (111-1 to 111-N). The layer-2 protocol processing unit (113) has a filtering function for blocking frames other than a clock-time synchronization frame during transfer involving a port selected from the plurality of physical ports (111-1 to 111-N) as a port that relays only the clock-time synchronization frame used for synchronizing clock time.

Abstract: A communication apparatus is mounted on a train and forms a train communication system together with a system control apparatus that generates control frames including general and low-latency frames. The communication apparatus includes: a general transfer processing unit that stores the general frame; a low latency transfer processing unit that stores the low-latency frame, the low latency frame requiring transferring with lower latency than the general frame; a frame identification unit that identifies priority of the control frame and outputs the control frame to the general transfer processing unit or the low latency transfer processing unit based on a priority setting table indicating the priority of the control frame and set in the identification unit; an output control unit that preferentially transfers the low-latency frame over the general frame; and a control unit that modifies the priority setting table.

Abstract: A transfer device includes an output-port decision unit to decide, on the basis of storage information stored in a frame input, an output port from which the frame is output from among a plurality of ports, an allocation unit to associate an input port to which the frame is input with an output port from which a frame which is transferred by a cut-through method is output on a one-to-one basis, and allocate a first frame to a first pathway transferring by the cut-through method and allocate a second frame to a second pathway transferring by a store-and-forward method on the basis of type information of an input port to which a frame has been input, class information of the frame, and the output port decided by the output-port decision unit, and an IET-output control unit to output the first frame from the output port, decide whether to divide the second frame on the basis of the class information of the second frame, and output the second frame from the output port on the basis of decision.

Abstract: A communication apparatus is mounted on a train and forms a train communication system together with a system control apparatus that generates control frames including general and low-latency frames. The communication apparatus includes: a general transfer processing unit that stores the general frame; a low latency transfer processing unit that stores the low-latency frame, the low latency frame requiring transferring with lower latency than the general frame; a frame identification unit that identifies priority of the control frame and outputs the control frame to the general transfer processing unit or the low latency transfer processing unit based on a priority setting table indicating the priority of the control frame and set in the identification unit; an output control unit that preferentially transfers the low-latency frame over the general frame; and a control unit that modifies the priority setting table.

Abstract: Provided is a transfer device (200) that includes a plurality of ports to and from each of which a layer-2 frame is input and output; a frame identification unit (221) that identifies whether or not the frame has been encrypted; an address filter unit (222) that decides one of the plurality of ports from which the frame is to be output; an encryption necessity determination unit (223) that has an encryption necessity determination table depending on destination information and priority information which are included in each frame, and a decryption necessity determination table depending on the destination information included in each frame, and when the frame has not been encrypted, determines whether or not encryption is necessary for the frame based on the encryption necessity determination table, and when the frame has been encrypted, determines whether or not decryption is necessary for the frame based on the decryption necessity determination table; an encryption decryption processing unit (225) that enc

Abstract: To include an FCS code calculation unit to calculate a first code that is an FCS code of a received frame, an FCS check unit to compare the first code with a second code that is an FCS code stored in the received frame, and to output a first comparison result indicating a match or no match between two codes, an inverse FCS check unit to compare the first code with a third code obtained by inverting each bit of the second code, and to output a second comparison result indicating a match or no match between two codes, an error determination unit to determine an error state of the received frame, and an FCS update unit to update, if the second comparison result indicates no match, the second code with a fourth code obtained by inverting each bit of the first code.

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: 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 includes an output-port decision unit to decide, on the basis of storage information stored in a frame input, an output port from which the frame is output from among a plurality of ports, an allocation unit to associate an input port to which the frame is input with an output port from which a frame which is transferred by a cut-through method is output on a one-to-one basis, and allocate a first frame to a first pathway transferring by the cut-through method and allocate a second frame to a second pathway transferring by a store-and-forward method on the basis of type information of an input port to which a frame has been input, class information of the frame, and the output port decided by the output-port decision unit, and an IET-output control unit to output the first frame from the output port, decide whether to divide the second frame on the basis of the class information of the second frame, and output the second frame from the output port on the basis of decision.

Abstract: Provided is a transfer device (200) that includes a plurality of ports to and from each of which a layer-2 frame is input and output; a frame identification unit (221) that identifies whether or not the frame has been encrypted; an address filter unit (222) that decides one of the plurality of ports from which the frame is to be output; an encryption necessity determination unit (223) that has an encryption necessity determination table depending on destination information and priority information which are included in each frame, and a decryption necessity determination table depending on the destination information included in each frame, and when the frame has not been encrypted, determines whether or not encryption is necessary for the frame based on the encryption necessity determination table, and when the frame has been encrypted, determines whether or not decryption is necessary for the frame based on the decryption necessity determination table; an encryption decryption processing unit (225) that enc

Abstract: A layer-2 switch, forming a communication network along with a communication terminal, includes a plurality of communication ports, frame identification units to identify a specific frame that is regularly transmitted from the communication terminal in the communication network, a setting unit to set a monitoring cycle and a reception threshold for detecting a loop path in the communication network, a monitoring unit to identify, for each of the communication ports, a plurality of communication terminals that are a source of the specific frame, and to count the number of the specific frames received from each of the communication terminals within the monitoring cycle, and a determination unit to determine whether a loop path is detected for each of the communication ports by comparing a counter value, which indicates the number of the specific frames, with the reception threshold, and to execute control to stop transmission and reception of the frame at the communication port at which a loop path is detected.

Abstract: A transfer apparatus has an input port and an output port, an input line speed of the input port and an output line speed of the output port being capable of being set to differ from each other. The transfer apparatus comprises, for each output port: a low-latency frame transmission buffer to store a low-latency frame received at the input port; a normal-latency frame transmission buffer to store a normal-latency frame that is a frame received at the input port, the normal-latency frame being permitted to be transferred with higher latency than the low-latency frame; a time calculation unit to calculate output start time of the low-latency frame by using information on a frame length of the low-latency frame, the input line speed, and the output line speed when the low-latency frame is received; and an output contention control unit to control transfer of the low-latency frame and the normal-latency frame by using the output start time.

Abstract: The relay device includes: a frame determination unit that determines a received frame between a high-priority frame and a low-priority frame for each output port on a basis of an identifier; a fixed-delay queue that delays the high-priority frame for a time equal to or longer than the sum of a specified transmission gap and a frame length long enough for a downstream device to be capable of correctly receiving and transferring or discarding a frame, and that transmits the high-priority frame; a low-priority frame storing unit that stores therein the low-priority frame; a transmission-frame selection unit that executes control to discontinue transmission of the low-priority frame when transmitting the high-priority frame, and to retransmit the low-priority frame; and an output control unit that selects a frame to be transmitted to the downstream device on a basis of the control by the transmission-frame selection unit.

Abstract: To include an FCS code calculation unit to calculate a first code that is an FCS code of a received frame, an FCS check unit to compare the first code with a second code that is an FCS code stored in the received frame, and to output a first comparison result indicating a match or no match between two codes, an inverse FCS check unit to compare the first code with a third code obtained by inverting each bit of the second code, and to output a second comparison result indicating a match or no match between two codes, an error determination unit to determine an error state of the received frame, and an FCS update unit to update, if the second comparison result indicates no match, the second code with a fourth code obtained by inverting each bit of the first code.

Abstract: A transfer apparatus has an input port and an output port, an input line speed of the input port and an output line speed of the output port being capable of being set to differ from each other. The transfer apparatus comprises, for each output port: a low-latency frame transmission buffer to store a low-latency frame received at the input port; a normal-latency frame transmission buffer to store a normal-latency frame that is a frame received at the input port, the normal-latency frame being permitted to be transferred with higher latency than the low-latency frame; a time calculation unit to calculate output start time of the low-latency frame by using information on a frame length of the low-latency frame, the input line speed, and the output line speed when the low-latency frame is received; and an output contention control unit to control transfer of the low-latency frame and the normal-latency frame by using the output start time.

Abstract: A communication apparatus according to the present invention includes a policer unit that, when notified of start of reception of a first frame, determines whether to discard or transfer the first frame on a basis of rate information indicating an amount of data per unit time calculated on a basis of a frame length and reception timing of a second frame received before the first frame; and a transfer processing unit that transfers the first frame in a cut-through mode, the first frame being determined by the policer unit to be transferred.