TRANSMISSION DEVICE, TRANSMISSION SYSTEM, AND TRANSMISSION METHOD

Abstract

A transmission device (40) comprises: a first transmission unit (41) that has a first port (41a) and a second port (41b), and controls whether a packet acquired from one port is to be output from the other port or to be output to a connected device; a second transmission unit (42) that has a third port (42a) and a fourth port (42b), and controls whether a packet acquired from one port is to be output from the other port or to be output to a connected device; a bypass control unit (43) that performs bypass control for bypassing between the ports of the first transmission unit (41) and the second transmission unit (42) when a power-off failure occurs in the first transmission unit (41) and the second transmission unit (42); and a packet control unit (44) that controls output of packets acquired by the first transmission unit (41) and the second transmission unit (42) when the bypass control is performed in an adjacent, connected transmission device (40).

Description

[Technical field]

[0001] The present disclosure relates to a transmission device, a transmission system, and a transmission method for use in a train. [Background technology]

[0002] Conventionally, in trains, a network is formed across multiple cars to control the devices mounted on each car through communication. When the network is formed by a single row of transmission lines, if even one transmission line fails, the network is divided and the train cannot control the devices. In response to this problem, Patent Document 1 discloses a technique in which, in a redundant network having multiple transmission repeaters, if a transmission repeater fails, the trunk transmission line is bypassed and packets on the trunk transmission line pass through the failed transmission repeater. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-117024 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the above conventional technology, the failed transmission repeater passes all packets on the trunk transmission line, and therefore passes packets addressed to devices connected to the failed transmission repeater without being able to capture them. Therefore, the above conventional technology has a problem in that packets addressed to devices connected to the failed transmission repeater are sent to the network, which may cause congestion and communication errors in the network.

[0005] The present disclosure has been made in view of the above, and has an object to provide a transmission device capable of improving redundancy in a transmission system including a plurality of transmission devices. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides a transmission device in a transmission system forming a redundant ring-shaped network by a plurality of transmission devices. The transmission device includes a first transmission unit having a first port and a second port and controlling whether a packet acquired from one port is output from the other port or to a device connected to the transmission device, a second transmission unit having a third port and a fourth port and controlling whether a packet acquired from one port is output from the other port or to a device connected to the transmission device, a bypass control unit performing bypass control to bypass each port of the first transmission unit and the second transmission unit when a power off failure occurs in the first transmission unit and the second transmission unit, and a packet control unit controlling output of the packets acquired by the first transmission unit and the second transmission unit when bypass control is performed in an adjacent transmission device connected via the first port and the third port or the second port and the fourth port. The packet control unit discards a packet acquired by at least one of the first transmission unit and the second transmission unit when bypass control is performed in the adjacent transmission device and the packet is addressed to a device connected to the adjacent transmission device. It is characterized by: Effect of the Invention

[0007] The transmission device of the present disclosure has an effect of improving redundancy in a transmission system including a plurality of transmission devices. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 shows an example of a configuration of a transmission system according to a first embodiment. [Diagram 2] FIG. 1 shows an example of a transmission system configured by a transmission device having two ports and relaying packets, as a comparative example. [Diagram 3] FIG. 3 is a simplified diagram of the transmission system shown in FIG. 1 according to the first embodiment in accordance with a comparative example transmission system shown in FIG. [Figure 4] FIG. 1 is a block diagram showing a configuration example of a transmission device according to a first embodiment; [Diagram 5] FIG. 1 is a first diagram showing an example of a transmission device performing alive monitoring in a transmission system according to a first embodiment; [Figure 6] FIG. 2 is a second diagram showing an example of a transmission device performing alive monitoring in a transmission system according to the first embodiment; [Figure 7] FIG. 1 is a diagram showing a state in which a transmission device in a transmission system according to a first embodiment is performing bypass control. [Figure 8] 1 is a flowchart showing an operation of a transmission device according to a first embodiment for performing bypass control. [Figure 9] 1 is a flowchart showing an operation of a transmission device according to a first embodiment for performing packet control. [Figure 10] FIG. 1 is a diagram showing an example of a configuration of a processing circuit in a transmission device according to a first embodiment when the processing circuit is realized by a processor and a memory. [Figure 11] FIG. 1 is a diagram showing an example of the configuration of a processing circuit in a transmission device according to a first embodiment when the processing circuit is realized by dedicated hardware; [Figure 12] FIG. 11 is a block diagram showing a configuration example of a transmission device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A transmission device, a transmission system, and a transmission method according to embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0010] Embodiment 1 FIG. 1 is a diagram showing a configuration example of a transmission system 80 according to the first embodiment. The transmission system 80 is a system mounted on a train 11 consisting of a plurality of vehicles 10-1, 10-2, ..., 10-N. In the following description, when the vehicles 10-1, 10-2, ..., 10-N are not distinguished from one another, they may be referred to as vehicles 10. In the example of FIG. 1, the train 11 is composed of N vehicles 10. Note that N is an integer of 2 or more. In the following description, for convenience, the vehicle 10-1 is the leading vehicle and the vehicle 10-N is the trailing vehicle, but the vehicle 10-1 may be the trailing vehicle and the vehicle 10-N may be the leading vehicle.

[0011] The transmission system 80 is composed of transmission devices 40-1a, 40-1b, 40-2, ..., 40-Na, 40-Nb and a train bus 70. The transmission system 80 is a system in which the transmission devices 40-1a, 40-1b, 40-2, ..., 40-Na, 40-Nb are connected by the train bus 70 to form a redundant ring-shaped network. As an example, in the normal transmission system 80, it is assumed that a packet generated by a CCU (Central Control Unit) 20-1 or CCU 20-N is transmitted clockwise on the train bus 70. The train bus 70 performs communication by, for example, 100BASE-TX, i.e., Ethernet (registered trademark).

[0012] The transmission device 40-1a is connected to an ED (End Device) 60-1a by a vehicle bus 50-1, the transmission device 40-1b is connected to an ED 60-1b by a vehicle bus 50-1, the transmission device 40-2 is connected to an ED 60-2 by a vehicle bus 50-2, ... the transmission device 40-Na is connected to an ED 60-Na by a vehicle bus 50-N, and the transmission device 40-Nb is connected to an ED 60-Nb by a vehicle bus 50-N. In the vehicle 10-1, which is the leading vehicle, the transmission device 40-1a and the transmission device 40-1b are connected by a train bus 70 and a vehicle bus 50-1, and in the vehicle 10-N, which is the trailing vehicle, the transmission device 40-Na and the transmission device 40-Nb are connected by a train bus 70 and a vehicle bus 50-N.

[0013] In the following description, when the transmission devices 40-1a, 40-1b, 40-2, ..., 40-Na, 40-Nb are not distinguished, they may be referred to as transmission devices 40. When the vehicle buses 50-1, 50-2, ..., 50-N are not distinguished, they may be referred to as vehicle buses 50. When the EDs 60-1a, 60-1b, 60-2, ..., 60-Na, 60-Nb are not distinguished, they may be referred to as EDs 60. The vehicle buses 50 and train buses 70, through which packets are transmitted and received between the transmission devices 40, are configured as, for example, a virtual local area network (VLAN).

[0014] In the example of FIG. 1, one ED 60 is connected to each transmission device 40, but this is not limited thereto. Two or more, i.e., a plurality of EDs 60 may be connected to each transmission device 40. The EDs 60 are, for example, but not limited to, a brake, an air conditioner, a door, etc. In the example of FIG. 1, the vehicle 10-1, which is the leading vehicle, and the vehicle 10-N, which is the trailing vehicle, are equipped with two transmission devices 40, and the vehicle 10-2, which is the intermediate vehicle, and the like are equipped with one transmission device 40, but this is not limited thereto. In general, the vehicle 10-1, which is the leading vehicle, and the vehicle 10-N, which is the trailing vehicle, among the vehicles 10 constituting the train 11, are equipped with more EDs 60 than the intermediate vehicles such as the vehicle 10-2. Therefore, in the example of FIG. 1, in order to reduce the monitoring burden of the EDs 60 of each transmission device 40, the vehicle 10-1, which is the leading vehicle, and the vehicle 10-N, which is the trailing vehicle, are equipped with two transmission devices 40.

[0015] The vehicle 10-1, which is the leading vehicle, includes a CCU 20-1. The CCU 20-1 is connected to the transmission devices 40-1a and 40-1b via a train bus 30-1. The vehicle 10-N, which is the trailing vehicle, includes a CCU 20-N. The CCU 20-N is connected to the transmission devices 40-Na and 40-Nb via the train bus 30-N. The CCUs 20-1 and 20-N have the same configuration, and in the train 11, it is sufficient that either one of the CCUs 20-1 and 20-N is operating. In the following description, the case where the CCU 20-1 is operating will be described. In the following description, when the CCUs 20-1 and 20-N are not distinguished from each other, they may be referred to as the CCU 20. In addition, when the train buses 30-1 and 30-N are not distinguished from each other, they may be referred to as the train bus 30. The train bus 30 performs communication, for example, via 100BASE-TX, that is, Ethernet.

[0016] The CCU 20-1 controls the operation of the ED 60 and the like mounted on the train 11. When the CCU 20-1 controls the operation of a certain ED 60, it generates a packet addressed to the ED 60 to be controlled, and outputs the generated packet to the transmission devices 40-1a and 40-1b via the train bus 30-1. The vehicle 10-1 ensures redundancy by setting the transmission devices 40 to which packets from the CCU 20-1 are output, that is, the transmission devices 40-1a and 40-1b. For example, if the destination of a packet acquired from the CCU 20-1 is the ED 60-Na, the transmission device 40-1b outputs the acquired packet to the transmission device 40-2 of the adjacent vehicle 10-2. The transmission device 40-1a outputs the acquired packet to the adjacent transmission device 40-1b. When the packet acquired from the transmission device 40-1a is the same as the already acquired packet, the transmission device 40-1b discards the packet acquired from the transmission device 40-1a without outputting it to the transmission device 40-2 of the adjacent vehicle 10-2. Also, when the destination of the packet acquired from the CCU 20-1 is the ED 60-1b, the transmission device 40-1b outputs the acquired packet to the ED 60-1b via the vehicle bus 50-1 without outputting it to the transmission device 40-2 of the adjacent vehicle 10-2.

[0017] In the first embodiment, the transmission device 40 has two functions of a general transmission device corresponding to the transmission repeater described in the prior art document. FIG. 2 is a diagram showing an example of a transmission system 800, as a comparative example, configured by the transmission device 400 having two ports and relaying packets. In the transmission system 800 of the comparative example, each transmission device 400 is connected to the train bus 700 by two ports. In the transmission system 800 of the comparative example, even if one transmission device 400 fails, the remaining transmission devices 400 can continue communication via the train bus 700.

[0018] FIG. 3 is a simplified diagram of the transmission system 80 shown in FIG. 1 according to the first embodiment, in accordance with the transmission system 800 of the comparative example shown in FIG. 2. In the transmission system 80, each transmission device 40 is connected to the train bus 70 through four ports. In terms of general transmission functions, the transmission device 40 has two functions equivalent to those of the transmission device 400 shown in FIG. 2. In the transmission system 80, for example, when the central transmission device 40 shown in FIG. 3 breaks down and is unable to relay packets, the remaining transmission devices 40 are unable to continue communication via the train bus 70. Therefore, the transmission device 40 of the first embodiment bypasses between ports in the event of a power-off failure, and outputs a packet acquired from one transmission device 40 to the other transmission device 40.

[0019] Here, if the transmission device 40 with the power off failure bypasses and outputs all packets, it will also output packets addressed to the ED 60 connected to the transmission device 40 with the power off failure. In this case, packets addressed to the ED 60 connected to the transmission device 40 with the power off failure will continue to flow through the train bus 70 unless another transmission device 40 takes action such as accepting or discarding the packets. Therefore, in the first embodiment, the transmission device 40 adjacent to the transmission device 40 with the power off failure performs control to discard packets addressed to the ED 60 connected to the transmission device 40 with the power off failure.

[0020] The configuration and operation of the transmission device 40 will be described in detail. Fig. 4 is a block diagram showing an example of the configuration of the transmission device 40 according to the first embodiment. The transmission device 40 includes a first transmission unit 41, a second transmission unit 42, a bypass control unit 43, and a packet control unit 44.

[0021] The first transmission unit 41 has a first port 41a and a second port 41b. The first transmission unit 41 controls whether a packet acquired from one port is output from the other port or output to the ED60, which is a connected device. That is, when the transmission device 40 is operating normally, the first transmission unit 41 acquires a packet from one port, and outputs the packet addressed to the ED60 to which the packet is addressed to the connected ED60, and outputs the packet addressed to the ED60 from the other port if the packet is not addressed to the ED60 to which the packet is addressed. When the first transmission unit 41 is operating normally, it performs the same operation as one transmission device 400 shown in FIG. 2.

[0022] The second transmission unit 42 has a third port 42a and a fourth port 42b. The second transmission unit 42 controls whether a packet acquired from one port is output from the other port or output to the ED60, which is a connected device. That is, when the transmission device 40 is operating normally, the second transmission unit 42 acquires a packet from one port, and outputs the packet addressed to the connected ED60 to the connected ED60, and outputs the packet addressed to the connected ED60 from the other port when the packet is not addressed to the connected ED60. When the second transmission unit 42 is operating normally, it performs the same operation as one transmission device 400 shown in FIG. 2.

[0023] The bypass control unit 43, when there is a power-off failure of the first transmission unit 41 and the second transmission unit 42, performs bypass control to bypass the respective ports of the first transmission unit 41 and the second transmission unit 42. Specifically, when there is a power-off failure of the first transmission unit 41 and the second transmission unit 42, the bypass control unit 43 performs the above-mentioned bypass control by bypassing the first port 41a and the second port 41b in the first transmission unit 41 to output a packet acquired from one port from the other port, and by bypassing the third port 42a and the fourth port 42b in the second transmission unit 42 to output a packet acquired from one port from the other port.

[0024] The bypass control unit 43 has a function of turning on the B contact in the first transmission unit 41 and turning on the B contact in the second transmission unit 42 when the first transmission unit 41 and the second transmission unit 42 have a power off failure. Therefore, the transmission device 40 may be configured to include a bypass control unit 43 for the first transmission unit 41 and a bypass control unit 43 for the second transmission unit 42, that is, to include two bypass control units 43. When the transmission device 40 has two bypass control units 43, the two bypass control units 43 may cooperate with each other by a method such as periodically communicating with each other, and may perform bypass control only when both the first transmission unit 41 and the second transmission unit 42 have a power off failure. Note that, when only one of the first transmission unit 41 and the second transmission unit 42 has a power off failure and the other is operating normally, the bypass control unit 43 may or may not perform bypass control on the transmission unit with the power off failure.

[0025] When bypass control is being performed in the adjacent transmission device 40 connected via the first port 41a and the third port 42a or the second port 41b and the fourth port 42b, the packet control unit 44 controls the output of the packet acquired by the first transmission unit 41 and the second transmission unit 42. For example, in the case of the transmission device 40-1b shown in FIG. 1, the adjacent transmission device 40 connected via the first port 41a and the third port 42a is the transmission device 40-1a, and the adjacent transmission device 40 connected via the second port 41b and the fourth port 42b is the transmission device 40-2. When bypass control is being performed in the adjacent transmission device 40, if a packet acquired by at least one of the first transmission unit 41 and the second transmission unit 42 is a packet addressed to the ED 60, which is a device connected to the adjacent transmission device 40, the packet control unit 44 discards the packet.

[0026] Specifically, a case will be described in which the transmission device 40-1b in the transmission system 80 has a power-off failure, the transmission device 40-1b performs bypass control, and the transmission device 40-2 performs packet control. FIG. 5 is a first diagram showing an example of alive monitoring performed by the transmission device 40 in the transmission system 80 according to the first embodiment. In the example of FIG. 5, a situation is shown in which the transmission device 40-1b periodically transmits a hello packet to the transmission device 40-2. Although not shown in FIG. 5, it is assumed that hello packets are also transmitted and received between the other transmission devices 40. The transmission device 40-2 periodically receives a hello packet from the transmission device 40-1b, thereby determining that the transmission device 40-1b is operating normally. FIG. 6 is a second diagram showing an example of alive monitoring performed by the transmission device 40 in the transmission system 80 according to the first embodiment. The transmission device 40-2 determines that the transmission device 40-1b is not operating normally because it has stopped receiving a hello packet from the transmission device 40-1b. In other words, when the packet control unit 44 no longer receives hello packets that are periodically transmitted from the adjacent transmission device 40, it determines that the first transmission unit 41 and the second transmission unit 42 of the adjacent transmission device 40 have experienced a power-off failure and that bypass control is being performed in the adjacent transmission device 40.

[0027] 7 is a diagram showing a state in which the transmission device 40-1b performs bypass control in the transmission system 80 according to the first embodiment. The transmission device 40-1b bypasses the packet acquired from the transmission device 40-1a and outputs it to the transmission device 40-2 under the control of the bypass control unit 43. In this case, the transmission device 40-1b also bypasses the packet addressed to the ED 60-1b and outputs it to the transmission device 40-2. Therefore, the transmission device 40-2 that has determined that the transmission device 40-1b is not operating normally discards the packet addressed to the ED 60-1b connected to the transmission device 40-1b among the packets acquired from the transmission device 40-1b. This allows the transmission device 40-2 to avoid the outflow of the packet addressed to the ED 60-1b, which is an unnecessary packet for the transmission device 40 at the subsequent stage, to the transmission device 40 at the subsequent stage.

[0028] The packet control unit 44 of the transmission device 40-2 has, for example, two VLAN tables, and switches the VLAN table depending on whether the adjacent transmission device 40-1b is operating normally, and controls whether the acquired packet is output to the downstream transmission device 40, output to ED60-2, or discarded. Specifically, the packet control unit 44 of the transmission device 40-2 uses a VLAN table that is defined to output packets addressed to ED60 connected to the downstream transmission device 40 to the next transmission device 40-3 (not shown) and to output packets addressed to ED60-2 to ED60-2 when the transmission device 40-1b is operating normally. The packet control unit 44 of the transmission device 40-2 uses a VLAN table that is defined to output packets addressed to ED60 connected to the downstream transmission device 40 to the next transmission device 40-3 (not shown), output packets addressed to ED60-2 to ED60-2, and discard packets addressed to ED60-1b when the transmission device 40-1b is not operating normally.

[0029] In the transmission system 80, it is assumed that a power-off failure occurs in a plurality of transmission devices 40. Therefore, the packet control unit 44 of the transmission device 40 may hold a VLAN table that not only discards packets addressed to the ED 60 connected to the adjacent transmission device 40, but also discards packets addressed to the ED 60 connected to a plurality of upstream transmission devices 40 with the CCU 20, which is the source of the packet, as the upstream side. The VLAN table provided in the packet control unit 44 of the transmission device 40 can be set by the installer of the transmission system 80, or may be set by another person.

[0030] The operation of the transmission device 40 will be described using a flowchart. FIG. 8 is a flowchart showing the operation of the transmission device 40 according to the first embodiment performing bypass control. In the transmission device 40, the bypass control unit 43 judges whether the first transmission unit 41 and the second transmission unit 42 have a power-off failure (step S1). For example, the bypass control unit 43 may periodically communicate with the first transmission unit 41 and the second transmission unit 42 to judge whether the first transmission unit 41 and the second transmission unit 42 have a power-off failure, or may judge whether the first transmission unit 41 and the second transmission unit 42 have a power-off failure by checking whether the first transmission unit 41 and the second transmission unit 42 periodically transmit hello packets. If the first transmission unit 41 and the second transmission unit 42 do not have a power-off failure (step S1: No), the bypass control unit 43 continues to judge whether the first transmission unit 41 and the second transmission unit 42 have a power-off failure (step S1). If the first transmission unit 41 and the second transmission unit 42 have a power-off failure (step S1: Yes), the bypass control unit 43 performs the bypass control as described above (step S2).

[0031] 9 is a flowchart showing an operation of the transmission device 40 according to the first embodiment to perform packet control. In the transmission device 40, the packet control unit 44 judges whether or not the bypass control is being performed in the adjacent transmission device 40 (step S11). As described above, the packet control unit 44 can judge whether or not the bypass control is being performed in the adjacent transmission device 40 depending on whether or not a hello packet is received from the adjacent transmission device 40. If the bypass control is not being performed in the adjacent transmission device 40 (step S11: No), the packet control unit 44 continues to judge whether or not the bypass control is being performed in the adjacent transmission device 40 (step S11). If the bypass control is being performed in the adjacent transmission device 40 (step S11: Yes), the packet control unit 44 performs the above-mentioned packet control to discard packets addressed to the ED 60 connected to the adjacent transmission device 40 (step S12).

[0032] Next, a hardware configuration of the transmission device 40 according to the first embodiment will be described. In the transmission device 40, the first transmission unit 41, the second transmission unit 42, the bypass control unit 43, and the packet control unit 44 are realized by processing circuits. The processing circuit may be a memory that stores a program and a processor that executes the program stored in the memory, or may be dedicated hardware. The processing circuit is also called a control circuit.

[0033] FIG. 10 is a diagram showing an example of the configuration of the processing circuit 90 in the case where the processing circuit of the transmission device 40 according to the first embodiment is realized by a processor 91 and a memory 92. The processing circuit 90 shown in FIG. 10 is a control circuit and includes a processor 91 and a memory 92. When the processing circuit 90 is configured with the processor 91 and the memory 92, each function of the processing circuit 90 is realized by software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 92. In the processing circuit 90, each function is realized by the processor 91 reading and executing the program stored in the memory 92. That is, the processing circuit 90 includes a memory 92 for storing a program that results in the processing of the transmission device 40 being executed. This program can also be said to be a program for causing the transmission device 40 to execute each function realized by the processing circuit 90. This program may be provided by a storage medium in which the program is stored, or may be provided by other means such as a communication medium.

[0034] The program includes a first step in which a first transmission unit 41 has a first port 41a and a second port 41b, and controls whether a packet acquired from one of the ports is output from the other port or to an ED 60, which is a connected device; a second step in which a second transmission unit 42 has a third port 42a and a fourth port 42b, and controls whether a packet acquired from one of the ports is output from the other port or to an ED 60, which is a connected device; and a bypass control unit 43 controls the first transmission unit 41 and the second port 42b to output a packet acquired from one of the ports from the other port or to an ED 60, which is a connected device. It can also be said that the program causes the transmission device 40 to execute a third step of performing bypass control to bypass each port of the first transmission unit 41 and the second transmission unit 42 when a power-off failure occurs in the second transmission unit 42, and a fourth step of controlling the output of packets acquired by the first transmission unit 41 and the second transmission unit 42 when bypass control is being performed in an adjacent transmission device 40 connected to the packet control unit 44 via the first port 41a and the third port 42a or the second port 41b and the fourth port 42b.

[0035] Here, the processor 91 is, for example, a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor), etc. Also, the memory 92 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc), etc.

[0036] FIG. 11 is a diagram showing an example of the configuration of the processing circuit 93 in the transmission device 40 according to the first embodiment when the processing circuit is realized by dedicated hardware. The processing circuit 93 shown in FIG. 11 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these. The processing circuit 93 may be partially realized by dedicated hardware and partially realized by software or firmware. In this way, the processing circuit 93 can realize each of the above-mentioned functions by dedicated hardware, software, firmware, or a combination of these.

[0037] As described above, according to the present embodiment, in the transmission device 40, when the first transmission unit 41 and the second transmission unit 42 experience a power-off failure, the bypass control unit 43 performs bypass control to bypass the ports of the first transmission unit 41 and the second transmission unit 42. In addition, when the bypass control is performed in the adjacent transmission device 40, the packet control unit 44 performs packet control to discard packets addressed to the ED 60 connected to the adjacent transmission device 40. As a result, the transmission device 40 can continue communication in the transmission system 80 even if any of the transmission devices 40 in the transmission system 80 experiences a power-off failure. The transmission device 40 can improve redundancy in the transmission system 80 including a plurality of transmission devices 40.

[0038] Furthermore, compared with the transmission device 400 shown in FIG. 2, the transmission device 40 can reduce the number of transmission devices 40 used in the transmission system 80, thereby improving the workability when installing the transmission device 40 in the vehicle 10 and reducing the amount of equipment that requires periodic maintenance.

[0039] Embodiment 2 In the first embodiment, when the first transmission unit 41 and the second transmission unit 42 in the adjacent transmission device 40 have a power-off failure and bypass control is being performed, the transmission device 40 performs packet control to discard packets addressed to the ED 60 connected to the adjacent transmission device 40. Here, the CCU 20 that is the source of the packets does not recognize the existence of the transmission device 40 performing bypass control, and therefore continues to output packets addressed to the ED 60 connected to the transmission device 40 performing bypass control.

[0040] Therefore, the transmission device 40 performing packet control may instruct the CCU 20 to stop transmitting packets addressed to the ED 60 connected to the adjacent transmission device 40 performing bypass control. That is, in the transmission device 40 performing packet control, the packet control unit 44 instructs the device that is the sender of the discarded packet to stop transmitting packets addressed to the same destination as the destination of the discarded packet.

[0041] As a result, the transmission device 40 performing packet control will no longer receive packets addressed to the ED 60 connected to the adjacent transmission device 40 performing bypass control, thereby reducing the processing load for discarding packets.

[0042] Embodiment 3 In embodiment 1, the transmission device 40 had a bypass control unit 43 separate from the first transmission unit 41 and the second transmission unit 42, but the first transmission unit 41 and the second transmission unit 42 may have the functions of the bypass control unit 43.

[0043] 12 is a block diagram showing a configuration example of a transmission device 40 according to the third embodiment. The transmission device 40 includes a first transmission unit 45, a second transmission unit 46, and a packet control unit 44. The first transmission unit 45 includes a bypass control unit 43a. Similarly, the second transmission unit 46 includes a bypass control unit 43b. In the transmission device 40 shown in FIG. 12, the bypass control unit 43a included in the first transmission unit 45 and the bypass control unit 43b included in the second transmission unit 46 have the same functions as the bypass control unit 43 of the first embodiment.

[0044] In the third embodiment, the bypass control unit 43a of the first transmission unit 45 may, as a bypass control, bypass the first port 41a and the second port 41b in the first transmission unit 45 and output a packet acquired from one port from the other port when the first transmission unit 45 has a power-off failure. Similarly, the bypass control unit 43b of the second transmission unit 46 may, as a bypass control, bypass the third port 42a and the fourth port 42b in the second transmission unit 46 and output a packet acquired from one port from the other port when the second transmission unit 46 has a power-off failure. The transmission device 40 may be configured such that the bypass control unit 43a of the first transmission unit 45 and the bypass control unit 43b of the second transmission unit 46 cooperate with each other by periodically communicating with each other, and the same bypass control as in the first embodiment may be performed only when both the first transmission unit 45 and the second transmission unit 46 have a power-off failure. When only one of the first transmitting unit 45 and the second transmitting unit 46 has a power-off failure and the other is operating normally, the bypass control units 43a and 43b may or may not perform bypass control on the transmitting unit with the power-off failure. Even in this case, the transmitting device 40 can obtain the same effects as in the first embodiment.

[0045] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. Also, parts of the configurations may be omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0046] 10, 10-1, 10-2 to 10-N Vehicle, 11 Train, 20-1, 20-N CCU, 30-1, 30-N, 70, 700 Train bus, 40, 40-1a, 40-1b, 40-2 to 40-Na, 40-Nb, 400 Transmission device, 41, 45 First transmission unit, 41a First port, 41b Second port, 42, 46 Second transmission unit, 42a Third port, 42b Fourth port, 43, 43a, 43b Bypass control unit, 44 Packet control unit, 50-1, 50-2 to 50-N Vehicle bus, 60-1a, 60-1b, 60-2 to 60-Na, 60-Nb ED, 80, 800 Transmission system, 90, 93 Processing circuit, 91 Processor, 92 Memory.

Claims

1. A transmission device in a transmission system that forms a redundant ring-shaped network using a plurality of transmission devices, a first transmission unit having a first port and a second port, and controlling whether a packet acquired from one port is output from the other port or output to a device connected to the transmission device; a second transmission unit having a third port and a fourth port, and controlling whether a packet acquired from one of the ports is output from the other port or output to the device connected to the transmission device; a bypass control unit that performs bypass control for bypassing between each port of the first transmission unit and the second transmission unit when a power-off failure occurs in the first transmission unit and the second transmission unit; a packet control unit that controls output of packets acquired by the first transmission unit and the second transmission unit when the bypass control is being performed in an adjacent transmission device connected via the first port and the third port or the second port and the fourth port; Equipped with the packet control unit, when the bypass control is being performed in the adjacent transmission device, discards a packet acquired by at least one of the first transmission unit and the second transmission unit if the packet is addressed to a device connected to the adjacent transmission device; A transmission device comprising:

2. the packet control unit instructs a device that is a transmission source of the discarded packet to stop transmitting packets having the same destination as the discarded packet; 2. The transmission device according to claim 1 .

3. when the packet control unit does not receive a hello packet periodically transmitted from the adjacent transmission device, the packet control unit determines that a power-off failure has occurred in the first transmission unit and the second transmission unit of the adjacent transmission device, and that the bypass control is being performed in the adjacent transmission device.

3. The transmission device according to claim 1, wherein the first and second inputs are connected to the first and second inputs.

4. the bypass control unit, when a power off failure occurs in the first transmission unit and the second transmission unit, performs the bypass control by bypassing the first port and the second port in the first transmission unit to output a packet acquired from one port from the other port, and by bypassing the third port and the fourth port in the second transmission unit to output a packet acquired from one port from the other port.

3. The transmission device according to claim 1, wherein the first and second inputs are connected to the first and second inputs.

5. 3. A transmission system comprising a plurality of transmission devices according to claim 1 or 2, forming a redundant ring network.

6. A transmission method for a transmission device in a transmission system that forms a redundant ring-shaped network using a plurality of transmission devices, comprising: a first step of controlling whether a packet acquired from one of the first and second ports is output from the other port or output to a device connected to the transmission device, the first transmission unit having a first port and a second port; a second step of controlling whether a packet acquired from one of the ports is output from the other port or output to the device connected to the transmission device, the second transmission unit having a third port and a fourth port; a third step of a bypass control unit performing bypass control for bypassing between each port of the first transmission unit and the second transmission unit when a power-off failure occurs in the first transmission unit and the second transmission unit; a fourth step of controlling, by a packet control unit, output of packets acquired by the first transmission unit and the second transmission unit when the bypass control is being performed in an adjacent transmission device connected via the first port and the third port or the second port and the fourth port; Including, In the fourth step, when the bypass control is being performed in the adjacent transmission device, the packet control unit discards a packet acquired by at least one of the first transmission unit and the second transmission unit if the packet is a packet addressed to a device connected to the adjacent transmission device. A transmission method comprising:

7. In the fourth step, the packet control unit instructs a device that is a transmission source of the discarded packet to stop transmitting packets having the same destination as that of the discarded packet.

7. The transmission method according to claim 6.

8. In the fourth step, when the packet control unit does not receive a hello packet periodically transmitted from the adjacent transmission device, the packet control unit determines that the first transmission unit and the second transmission unit of the adjacent transmission device have a power-off failure and that the bypass control is being performed in the adjacent transmission device.

8. A transmission method according to claim 6 or 7.

9. In the third step, when a power-off failure occurs in the first transmission unit and the second transmission unit, the bypass control unit causes the first transmission unit to bypass the first port and the second port and outputs a packet acquired from one port from the other port, and causes the second transmission unit to bypass the third port and the fourth port and outputs a packet acquired from one port from the other port, as the bypass control.

8. A transmission method according to claim 6 or 7.

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