TRANSMISSION DEVICE, TRANSMISSION SYSTEM AND TRANSMISSION METHOD

Abstract

A transmission device (40) comprising: a first transmission unit (41) having a first port (41a) and a second port (41b), the first transmission unit (41) controlling whether a packet acquired from one of the ports is output from the other port or output to a connected device; a second transmission unit (42) having a third port (42a) and a fourth port (42b), the second transmission unit (42) controlling whether a packet acquired from one of the ports is output from the other port or output to the connected device;a bypass control unit (43) that performs bypass control to provide bypasses between the terminals of the first transmission unit (41) and between the terminals of the second transmission unit (42) when power-off failures occur 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) in a case where the bypass control is performed in an adjacent connected transmission device (40);

Description

Area

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

[0002] Trains conventionally have networks formed across a plurality of their cars so as to control devices, etc., installed in each car through communications with them. For the network formed by a single transmission line, a failure at any point in the transmission line will cause a network disconnection, so that the train cannot control the devices. To address such a problem, Patent Literature 1 discloses a method providing a redundant network including a plurality of retransmission devices designed to bypass a trunk transmission path when some retransmission devices fail, so that a packet in the trunk transmission path bypasses the failed retransmission device. Citation listPatent literature

[0003] Patent Literature 1: Japanese Patent Application Laid-Open No. 2006-117024 Summary of the inventionProblem to be solved by the invention

[0004] For the conventional method described above, the failed retransmission device allows the passage of all packets in the remote transmission path. This means that the failed retransmission device, which itself allows the passage of a packet addressed to a device connected to it, cannot accept such a packet. Thus, a problem with the conventional method described above is that the packet addressed to the device connected to the failed retransmission device flows into the network, which can cause congestion, communication failure, etc., in the network.

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

[0006] To solve the above problem and achieve the object, the present disclosure provides a transmission device in a transmission system including a plurality of transmission devices forming a redundant ring network. The transmission device comprises: a first transmission unit having a first port and a second port, the first transmission unit controlling whether a packet acquired from one of the ports is output from the other port or output to a connected device; a second transmission unit having a third port and a fourth port, the second transmission unit controlling whether a packet acquired from one of the ports is output from the other port or output to the connected device;a bypass control unit for performing bypass control to provide bypasses between the terminals of the first transmission unit and between the terminals of the second transmission unit when power-off failures occur in the first transmission unit and the second transmission unit; and a packet control unit for controlling output of packets acquired by the first transmission unit and the second transmission unit in a case where the bypass control is performed in an adjacent transmission device connected via the first terminal and the third terminal or via the second terminal and the fourth terminal. Effects of the invention

[0007] The transmission device of the present disclosure has the effect of improving redundancy in the transmission system including the plurality of transmission devices. Short description of the drawings Fig. 1 is a diagram illustrating an exemplary configuration of a transmission system according to a first embodiment. Fig. 2 is a diagram illustrating, as a comparative example, an exemplary transmission system including transmission devices each having two ports and forwarding packets. Fig. Figure 3 is a diagram illustrating the transmission system according to the Fig. 1 illustrated first embodiment, which has been simplified in accordance with the transmission system of the comparative example shown in Fig. 2 is specified. Fig. 4 is a block diagram illustrating an exemplary configuration of a transmission device according to the first embodiment. Fig. 5 is a first diagram showing an example in which a transmission device performs live monitoring or vital monitoring in the transmission system according to the first embodiment. Fig. 6 is a second diagram showing the example in which the transmission device performs live monitoring in the transmission system according to the first embodiment. Fig. 7 is a diagram illustrating a transmission device that performs bypass control in the transmission system according to the first embodiment. Fig. 8 is a flowchart illustrating an operation in which the transmission apparatus according to the first embodiment performs bypass control. Fig. 9 is a flowchart illustrating an operation in which the transmission apparatus according to the first embodiment performs packet control. Fig. 10 is a diagram illustrating an exemplary configuration of a processing circuit of the transmission device according to the first embodiment, the processing circuit being implemented by a processor and a memory. Fig. 11 is a diagram illustrating an exemplary configuration of a processing circuit of the transmission device according to the first embodiment, the processing circuit being implemented by dedicated hardware. Fig. 12 is a block diagram illustrating an exemplary configuration of a transmission device according to a third embodiment. Description of embodiments

[0008] Transmission devices, transmission systems, and transmission methods according to embodiments of the present disclosure will be described in detail below with reference to the drawings. First embodiment.

[0009] Fig. 1 is a diagram illustrating an exemplary configuration of a transmission system 80 according to a first embodiment. The transmission system 80 is a system to be installed in a train 11, which is defined by a plurality of cars 10-1, 10-2, ..., and 10-N. In the following description, the cars 10-1, 10-2, ..., and 10-N may be referred to collectively as cars 10 if they are not differentiated from each other. In the example of Fig. 1, train 11 comprises N cars 10. Note that N is an integer greater than or equal to 2. For simplicity, the following description assumes that car 10-1 is a first car and that car 10-N is a last car. However, car 10-1 could be defined as a last car, and car 10-N could be defined as a first car.

[0010] The transmission system 80 includes transmission devices 40-1a, 40-1b, 40-2, ..., 40-Na, and 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, and 40-Nb are connected to the train bus 70 to form a redundant ring network. The assumption is that, when the transmission system 80 is operating normally, for example, a packet generated by a central control unit (CCU) 20-1 or CCU 20-N is transmitted clockwise through the train bus 70. The train bus 70 performs communication using, for example, 100BASE-TX, i.e., Ethernet (registered trademark).

[0011] The transmission device 40-1a is connected to an end device (ED) 60-1a through a car bus 50-1, the transmission device 40-1b is connected to an ED 60-1b through the car bus 50-1, the transmission device 40-2 is connected to an ED 60-2 through a car bus 50-2, ..., the transmission device 40-Na is connected to an ED 60-Na through a car bus 50-N, and the transmission device 40-Nb is connected to an ED 60-Nb through the car bus 50-N. Furthermore, the transmission device 40-1a and the transmission device 40-1b in the first car, or car 10-1, are connected to each other through the train bus 70 and the car bus 50-1. The transmission device 40-Na and the transmission device 40-Nb in the last car, or in car 10-N, are connected to each other by the train bus 70 and the car bus 50-N.

[0012] In the following description, the transmission devices 40-1a, 40-1b, 40-2, ..., 40-Na, and 40-Nb could be collectively referred to as transmission devices 40 if they are not distinguished from one another. Furthermore, the railcars 50-1, 50-2, ..., and 50-N could be collectively referred to as railcars 50 if they are not distinguished from one another. Furthermore, the EDs 60-1a, 60-1b, 60-2, ..., 60-Na, and 60-Nb could be collectively referred to as EDs 60 if they are not distinguished from one another. For example, a virtual local area network (VLAN) is established for the railcars 50 and the train bus 70, through which packets are transmitted and received between the transmission devices 40.

[0013] In the example of Fig. 1, a single ED 60 is connected to each transmission device 40, but the configuration of the transmission system 80 according to the present embodiment is not limited thereto. Two or more EDs 60, ie, a plurality of EDs 60, could be connected to each of the transmission devices 40. Examples of the ED 60 include, but are not limited to, a brake, an air conditioning unit, and a door. In the example of Fig. 1, each of the car 10-1, which is the first car, and the car 10-N, which is the last car, includes two transmission devices 40, and middle cars including the car 10-2 each include a single transmission device 40, but the configuration of the transmission system 80 according to the present embodiment is not limited thereto. In general, among the cars 10 included in the train 11, the car 10-1, which is the first car, and the car 10-N, which is the last car, have the larger number of EDs 60 installed therein than a middle car, such as the car 10-2. For this reason, in the example, the Fig. 1, both the wagon 10-1, which is the first wagon, and the wagon 10-N, which is the last wagon, each have two transmission devices 40 for the purpose of reducing a load of monitoring the ED 60 from each transmission device 40.

[0014] Car 10-1, which is the first car, includes CCU 20-1. CCU 20-1 is connected to transmission devices 40-1a and 40-1b via a train bus 30-1. Furthermore, car 10-N, which is the last car, includes CCU 20-N. CCU 20-N is connected to transmission devices 40-Na and 40-Nb via a train bus 30-N. CCUs 20-1 and 20-N each have the same configuration, and only one of CCUs 20-1 and 20-N needs to be operating in train 11 at a time. The operation of CCU 20-1 will be described below. In the following description, CCUs 20-1 and 20-N may be referred to collectively as CCUs 20 if they are not distinguished from each other. Furthermore, train buses 30-1 and 30-N could be collectively referred to as train buses 30 if they are not differentiated from each other. Train buses 30 communicate using, for example, 100BASE-TX, ie, Ethernet.

[0015] The CCU 20-1 controls the operation of the EDs 60, etc., installed in the train 11. When controlling the operation of a specific ED 60, the CCU 20-1 generates a packet addressed to a control target ED 60 and outputs the generated packet to the transmission devices 40-1a and 40-1b via the train bus 30-1. The car 10-1 enables redundancy because the car 10-1 includes the transmission devices 40-1a and 40-1b, i.e., the two transmission devices 40, which are the destinations of the packet output from the CCU 20-1. For example, in a case where a packet acquired by the CCU 20-1 is addressed to the ED 60-Na, the transmission device 40-1b outputs the acquired packet to the transmission device 40-2 of the adjacent car 10-2. The transmission device 40-1a outputs an acquired packet to the adjacent transmission device 40-1b.If the packet that the transmission device 40-1b has acquired from the transmission device 40-1a is the same as the packet already acquired, the transmission device 40-1b discards the packet acquired from the transmission device 40-1a instead of outputting the packet to the transmission device 40-2 of the adjacent car 10-2. Furthermore, in a case where a packet acquired from the CCU 20-1 is addressed to the ED 60-1b, the transmission device 40-1b does not output the acquired packet to the transmission device 40-2 of the adjacent car 10-2, but outputs the packet to the ED 60-1b via the car bus 50-1.

[0016] In the first embodiment, the transmission device 40 functions like two general transmission devices corresponding to the retransmission device described in the prior art literature described above. Fig. 2 is a diagram illustrating, as a comparative example, an exemplary transmission system 800 including transmission devices 400, each having two ports and forwarding packets. In the transmission system 800 of the comparative example, each transmission device 400 is connected to a train bus 700 at its two ports. In the transmission system 800 of the comparative example, the remaining transmission devices 400 can continue communication via the train bus 700 even if one of the transmission devices 400 fails.

[0017] Fig. Fig. 3 is a diagram illustrating the transmission system 80 according to the first embodiment shown in Fig. 1, in a simple form corresponding to 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 at its four terminals. When a general transmission function occurs, the transmission device 40 functions like two of the Fig. 2 illustrated transmission devices 400. In the transmission system 80, the remaining transmission device 40, when the transmission device 40 located in the middle of the Fig. 3, for example, fails and cannot forward packets, may become unable to continue communication via the train bus 70. To address this, the transmission device 40 of the first embodiment provides inter-terminal bypassing at the time of a power-down failure, whereby a packet acquired by one of the transmission devices 40 is output to the other transmission device 40.

[0018] The transmission device 40 with a shutdown failure outputs all packets via the bypass, including a packet addressed to the ED 60 connected to that transmission device 40 itself. In this case, the packet addressed to the ED 60 connected to the transmission device 40 with the shutdown failure continues to flow through the train bus 70 unless another transmission device 40 takes action, such as accepting or discarding the packet. To address this, in the first embodiment, the transmission device 40 adjacent to the transmission device 40 with the shutdown failure performs control such that the packet addressed to the ED 60 connected to the transmission device 40 with the shutdown failure is discarded.

[0019] The configuration and operation of the transmission device 40 will be described in detail. Fig. Figure 4 is a block diagram illustrating an exemplary 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.

[0020] 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 of the ports is output from the other port or output to the ED 60, which is a connected device. This means that during normal operation of the transmission device 40, the first transmission unit 41 accepts a packet acquired from one of the ports and outputs the acquired packet to the connected ED 60 if the packet is addressed to the connected ED 60; the first transmission unit 41 outputs the acquired packet from the other port if the acquired packet is not addressed to the connected ED 60. The first transmission unit 41 in the normal operating state operates in the same way as a single transmission device 400 used in Fig. 2 is illustrated.

[0021] 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 of the ports is output from the other port or output to the ED 60, which is the connected device. This means that during normal operation of the transmission device 40, the second transmission unit 42 accepts a packet acquired from one of the ports and outputs the acquired packet to the connected ED 60 if the packet is addressed to the connected ED 60; and the second transmission unit 42 outputs the acquired packet from the other port if the acquired packet is not addressed to the connected ED 60. The second transmission unit 42 operates in a normal operating state in the same manner as a single transmission device 400 operating in Fig. 2 is illustrated.

[0022] The bypass control unit 43 performs bypass control to provide bypasses between the terminals of the first transmission unit 41 and between the terminals of the second transmission unit 42 when shutdown failures occur in the first transmission unit 41 and the second transmission unit 42.More specifically, when power-off failures occur in the first transmission unit 41 and the second transmission unit 42, the bypass control unit 43 performs the above-described bypass control such that the bypass control unit 43 bypasses the first port 41a and the second port 41b in the first transmission unit 41 to allow a packet acquired from one of the ports to be output to the other port, and bypasses the third port 42a and the fourth port 42b in the second transmission unit 42 to allow a packet acquired from one of the ports to be output from the other port.

[0023] The bypass control unit 43 has a function of turning on a b-contact in the first transmission unit 41 and a function of turning on a b-contact in the second transmission unit 42 when shutdown failures occur in the first transmission unit 41 and the second transmission unit 42. Thus, the transmission device 40 could include two bypass control units 43, i.e., the bypass control unit 43 dedicated to the first transmission unit 41 and the bypass control unit 43 dedicated to the second transmission unit 42.In a case where the transmission device 40 includes the two bypass control units 43, the two bypass control units 43 may cooperate with each other by a method such as periodically performing communication therebetween, and may perform bypass control only when shutdown failures occur in both the first transmission unit 41 and the second transmission unit 42. Note that if a shutdown failure occurs in only the first transmission unit 41 or the second transmission unit 42 while the other transmission unit is operating normally, the bypass control unit 43 may optionally perform bypass control on the transmission unit experiencing the shutdown failure.

[0024] The packet control unit 44 controls the output of packets acquired by the first transmission unit 41 and the second transmission unit 42 when the neighboring transmission device 40 connected via the first terminal 41a and the third terminal 42a or via the second terminal 41b and the fourth terminal 42b performs the bypass control. The transmission device 40-1b connected in Fig. 1 is taken by way of example. In this case, the neighboring transmission device 40 connected to the transmission device 40-1b via the first port 41a and the third port 42a of the transmission device 40-1b is the transmission device 40-1a; the neighboring transmission device 40 connected to the transmission device 40-1b via the second port 41b and the fourth port 42b of the transmission device 40-1b is the transmission device 40-2. The packet control unit 44 discards a packet acquired by the first transmission unit 41 and / or the second transmission unit 42 during the bypass control in the neighboring transmission in a case where the packet is addressed to the ED 60, which is a device connected to the neighboring transmission device 40.

[0025] A case will be specifically described where, upon a power-off failure occurring in the transmission device 40-1b in the transmission system 80, 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 in which the transmission device 40 performs live monitoring in the transmission system 80 according to the first embodiment. Fig. Figure 5 shows a situation in which the transmission device 40-1b periodically transmits a Hello packet to the transmission device 40-2. It should be noted that, although Fig. 5, a Hello packet is transmitted and received between the other transmission devices 40. When a Hello packet is periodically received by the transmission device 40-1b, the transmission device 40-2 determines that the transmission device 40-1b is operating normally. Fig. 6 is a second diagram showing an example in which the transmission device 40 performs live monitoring in the transmission system 80 according to the first embodiment. When the transmission device 40-2 does not receive a Hello packet from the transmission device 40-1b, the transmission device 40-2 determines that the transmission device 40-1b is not operating normally. This means that when no Hello packet periodically transmitted from the neighboring transmission device 40 is received, the packet control unit 44 determines that shutdown failures have occurred in the first transmission unit 41 and the second transmission unit 42 of the neighboring transmission device 40, and bypass control is performed in the neighboring transmission device 40.

[0026] Fig. 7 is a diagram illustrating the transmission device 40-1b performing bypass control in the transmission system 80 according to the first embodiment. Under the control of the bypass control unit 43, the transmission device 40-1b bypasses a packet acquired from the transmission device 40-1a and outputs the packet to the transmission device 40-2. In this case, the transmission device 40-1b itself bypasses a packet addressed to the ED 60-1b and outputs the packet to the transmission device 40-2. To address this, the transmission device 40-2, which has determined that the transmission device 40-1b is not operating normally, discards a packet acquired from the transmission device 40-1b if the packet is addressed to the ED 60-1b connected to the transmission device 40-1b.In this transmission device 40-2, a packet addressed to the ED 60-1b, which is an unimportant packet for the transmission device 40 in a subsequent stage, does not flow to the subsequent transmission device 40.

[0027] The packet control unit 44 of the transmission device 40-2 includes, for example, two VLAN tables. Depending on whether the adjacent transmission device 40-1b is operating normally, the packet control unit 44 of the transmission device 40-2 switches between the VLAN tables and controls whether to output an acquired packet to the subsequent transmission device 40, output the acquired packet to the ED 60-2, or discard the acquired packet.More specifically, 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 specifies that: a packet addressed to the ED 60 connected to a transmission device 40 in a subsequent stage is output to a next transmission device 40-3 (not illustrated); and that a packet addressed to the ED 60-2 is output to the ED 60-2.When the transmission device 40-1b is not operating normally, the packet control unit 44 of the transmission device 40-2 uses a VLAN table that specifies that: a packet addressed to the ED 60 connected to the transmission device 40 in a subsequent stage is output to a next transmission device 40-3 (not illustrated); that a packet addressed to the ED 60-2 is output to the ED 60-2; and that a packet addressed to the ED 60-1b is discarded.

[0028] It should be noted that in the transmission system 80, it is also conceivable that power-down failures could occur in a plurality of transmission devices 40. Therefore, the packet control unit 44 of the transmission device 40 could store a VLAN table that specifies that not only a packet addressed to the ED 60 connected to the adjacent transmission device 40, but also packets addressed to the EDs 60 connected to a plurality of transmission devices 40 on an upstream side where the CCU 20 is located as a packet transmission source, are discarded. It should be noted that VLAN tables of the packet control unit 44 of the transmission device 40 could be set by an installer or the like of the transmission system 80, but they could also be set by another person.

[0029] An operation of the transmission device 40 will be described with reference to the flowcharts. Fig. 8 is a flowchart illustrating an operation in which the transmission device 40 according to the first embodiment performs bypass control. In the transmission device 40, the bypass control unit 43 determines whether shutdown failures have occurred in the first transmission unit 41 and the second transmission unit 42 (step S1). For example, the bypass control unit 43 may determine whether the shutdown failures have occurred in the first transmission unit 41 and the second transmission unit 42 by periodically communicating with the first transmission unit 41 and the second transmission unit 42. Alternatively, by checking whether the first transmission unit 41 and the second transmission unit 42 periodically transmit Hello packets, the bypass control unit 43 may determine whether the shutdown failures have occurred in the first transmission unit 41 and the second transmission unit 42.If no shutdown failure has occurred in the first transmission unit 41 and the second transmission unit 42 (step S1: No), the bypass control unit 43 continues to determine whether shutdown failures have occurred in the first transmission unit 41 and the second transmission unit 42 (step S1). If the shutdown failures have occurred in the first transmission unit 41 and the second transmission unit 42 (step S1: Yes), the bypass control unit 43 performs the bypass control as described above (step S2).

[0030] Fig. 9 is a flowchart illustrating an operation in which the transmission device 40 according to the first embodiment performs packet control. In the transmission device 40, the packet control unit 44 determines whether the bypass control is being performed in the neighboring transmission device 40 (step S11). As described above, depending on whether the transmission device 40 receives a Hello packet from the neighboring transmission device 40, the packet control unit 44 can determine whether the bypass control is being performed in the neighboring transmission device 40. If the bypass control is not being performed in the neighboring transmission device 40 (step S11: No), the packet control unit 44 proceeds to determine whether the bypass control is being performed in the neighboring transmission device 40 (step S11).When the bypass control is performed in the neighboring transmission device 40 (step S11: Yes), the packet control unit 44 performs the above-described packet control to discard a packet addressed to the ED 60 connected to the neighboring transmission device 40 (step S12).

[0031] 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 implemented by a processing circuit. The processing circuit may be a memory that stores programs and a processor that executes the programs stored in the memory. Alternatively, the processing circuit may be dedicated hardware. The processing circuit is also referred to as a control circuit.

[0032] Fig. Fig. 10 is a diagram illustrating an exemplary configuration of a processing circuit 90 of the transmission device 40 according to the first embodiment, wherein the processing circuit 90 is implemented as a processor 91 and a memory 92. The Fig. The processing circuit 90 illustrated in FIG. 10 is a control circuit and includes the processor 91 and the memory 92. In a case where the processing circuit 90 includes the processor 91 and the memory 92, each function of the processing circuit 90 is implemented by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 92. In the processing circuit 90, the processor 91 reads the program stored in the memory 92 and executes it to implement each function. This means that the processing circuit 90 includes the memory 92 for storing the program. As a result of executing the program, the transmission device 40 is caused to perform processing.It can also be said that this program is a program for causing the transmission device 40 to perform each function to be implemented by the processing circuit 90. This program could be provided by means of a storage medium in which the program has been stored, or could be provided by other means, such as a communications medium.

[0033] It can also be said that the program described above is a program for causing the transmission device 40 to perform: a first step in which the first transmission unit 41, which has the first port 41a and the second port 41b, performs control as to whether a packet acquired from one of the ports is output from the other port or output to the ED 60, which is a connected device; a second step in which the second transmission unit 42, which has the third port 42a and the fourth port 42b, performs control as to whether a packet acquired from one of the ports is output from the other port or output to the ED 60, which is the connected device;a third step in which the bypass control unit 43 performs bypass control to provide bypasses between the terminals of the first transmission unit 41 and between the terminals of the second transmission unit 42 when power-off failures occur in the first transmission unit 41 and the second transmission unit 42; and a fourth step in which the packet control unit 44 controls output of packets acquired by the first transmission unit 41 and the second transmission unit 42 in a case where the bypass control is performed in the adjacent transmission device 40 connected via the first terminal 41a and the third terminal 42a or via the second terminal 41b and the fourth terminal 42b.

[0034] Here, the processor 91 is, for example, a central processing unit (CPU), a processing device, an arithmetic device, a microprocessor, a microcomputer, or a digital signal processor (DSP). Further, examples of the memory 92 include non-volatile or volatile semiconductor memories such as random access memory (RAM), read-only memory (ROM), flash memory, erasable programmable ROM (EPROM), and electronic EPROM (EEPROM (registered trademark)), a magnetic disk, a floppy disk, an optical disk, a compact disk, a mini disk, and a DVD (digital versatile disc).

[0035] Fig. 11 is a diagram illustrating an exemplary configuration of a processing circuit 93 of the transmission device 40 according to the first embodiment, wherein the processing circuit 93 is implemented by dedicated hardware. Fig. The processing circuit 93 illustrated in Figure 11 corresponds, for example, to a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof. A portion of the processing circuit 93 may be implemented by dedicated hardware, and another portion of the processing circuit 93 may be implemented by software or firmware. Thus, the processing circuit 93 may implement any of the functions described above using dedicated hardware, software, firmware, or a combination thereof.

[0036] As described above, in the transmission device 40 according to the present embodiment, the bypass control unit 43 performs bypass control to provide bypasses between the terminals of the first transmission unit 41 and between the terminals of the second transmission unit 42 when power failures occur in the first transmission unit 41 and the second transmission unit 42. Furthermore, when the bypass control is performed in the adjacent transmission device 40, the packet control unit 44 performs packet control to discard a packet 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 the power failure occurs in any of the transmission devices 40 in the transmission system 80.The transmission device 40 can improve redundancy in the transmission system 80 including the plurality of transmission devices 40.

[0038] Since it is possible to reduce the number of transmission devices 40 used in the transmission system 80 compared to the transmission device 400 as shown in FIG. Fig. 2, it is also possible to improve feasibility in installing the transmission system 80 in the car 10 and also to reduce the number of maintenance target devices that are regularly inspected.

[0039] Second embodiment.

[0037] In the first embodiment, when bypass control is performed in the neighboring transmission device 40 due to the shutdown failures of the first transmission unit 41 and the second transmission unit 42, the transmission device 40 performs packet control to discard a packet addressed to the ED 60 connected to the neighboring transmission device 40. In this case, the CCU 20, which is a transmission source of packets, does not recognize the existence of the transmission device 40 performing bypass control. For this reason, the CCU 20 continues to output packets addressed to the ED 60 connected to the transmission device 40 performing bypass control.

[0038] To address this, the transmission device 40 performing packet control could instruct the CCU 20 to stop transmitting packets addressed to the ED 60 connected to the neighboring transmission device 40 performing bypass control. This means that in the transmission device 40 performing packet control to discard a packet transmitted from a transmission source device, the packet control unit 44 instructs the transmission source device to stop transmitting packets addressed to the same destination as the discarded packet.

[0039] As a result, the transmission device 40 performing packet control does not receive packets addressed to the ED 60 connected to the neighboring transmission device 40 performing bypass control. The transmission device 40 performing packet control can thus reduce the processing load for discarding packets. Third embodiment.

[0040] In the first embodiment, the transmission device 40 includes the bypass control unit 43 separately from the first transmission unit 41 and the second transmission unit 42. Meanwhile, the first transmission unit 41 and the second transmission unit 42 may have the function of the bypass control unit 43.

[0041] Fig. 12 is a block diagram illustrating an exemplary configuration of the transmission device 40 according to a third embodiment. The transmission device 40 includes a first transmission unit 45, a second transmission unit 46, and the 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 Fig. In the transmission device 40 illustrated in Fig. 12, the bypass control unit 43a included in the first transmission unit 45 and the bypass control unit 43b of the second transmission unit 46 have the same function as the bypass control unit 43 of the first embodiment.

[0042] In the third embodiment, when the power-down failure occurs in the first transmission unit 45, the bypass control unit 43a of the first transmission unit 45 may perform bypass control such that the bypass control unit 43a bypasses the first port 41a and the second port 41b in the first transmission unit 45, whereby a packet acquired from one of the ports can be output from the other port. Similarly, when the power-down failure occurs in the second transmission unit 46, the bypass control unit 43b of the second transmission unit 46 may perform bypass control such that the bypass control unit 43b bypasses the third port 42a and the fourth port 42b in the second transmission unit 46, whereby a packet acquired from one of the ports can be output from the other port.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 a method such as periodically performing communication therebetween, and perform the same bypass control as that in the first embodiment only when shutdown failures occur in both the first transmission unit 45 and the second transmission unit 46. Note that if the shutdown failure occurs in only the first transmission unit 45 or the second transmission unit 46 while the other transmission unit is operating normally, the bypass control units 43a and 43b may optionally perform bypass control on the transmission unit experiencing a shutdown failure.In this case, too, the transmission device 40 can achieve the same effect as in the first embodiment.

[0043] The configurations set forth in the embodiments above show examples, and it is possible to combine the configurations with another known technique or to combine the embodiments with each other, and it is also possible to partially omit or change the configurations without departing from the scope of the present disclosure. List of reference symbols

[0044] 10, 10-1, 10-2 to 10-N wagon; 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 terminal; 41b second terminal; 42, 46 second transmission unit; 42a third terminal; 42b fourth terminal; 43, 43a, 43b bypass control unit; 44 packet control unit; 50-1, 50-2 to 50-N wagon 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. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2006-117024

[0003]

Claims

[1] A transmission device in a transmission system comprising a plurality of transmission devices forming a redundant ring-shaped network, the transmission device comprising: a first transmission unit having a first port and a second port, the first transmission unit controlling whether a packet acquired from one of the ports is output from the other port or output to a connected device; a second transmission unit having a third port and a fourth port, the second transmission unit controlling whether a packet acquired from one of the ports is output from the other port or output to the connected device; a bypass control unit for performing bypass control to provide bypasses between the terminals of the first transmission unit and between the terminals of the second transmission unit when shutdown failures occur in the first transmission unit and in the second transmission unit; and a packet control unit for controlling an output of packets acquired by the first transmission unit and the second transmission unit in a case where the bypass control is performed in an adjacent transmission device connected via the first terminal and the third terminal or via the second terminal and the fourth terminal. [2] The transmission device according to claim 1, wherein the packet control unit discards a packet acquired by the first transmission unit and / or the second transmission unit during the bypass control in the neighboring transmission device in a case where the acquired packet is addressed to a device connected to the neighboring transmission device. [3] The transmission apparatus according to claim 2, wherein the packet control unit instructs a device to stop transmitting a packet addressed to a same destination as the discarded packet, the device being a transmission source of the discarded packet. [4] The transmission device according to any one of claims 1 to 3, wherein, when the transmission device does not receive a hello packet periodically transmitted from the neighboring transmission device, the packet control unit determines that power-off failures have occurred in the first transmission unit and in the second transmission unit of the neighboring transmission device, and that the bypass control is performed in the neighboring transmission device. [5] The transmission device according to any one of claims 1 to 4, wherein, when power-off failures occur in the first transmission unit and the second transmission unit, the bypass control unit performs bypass control such that the bypass control unit bypasses the first port and the second port in the first transmission unit to allow a packet acquired from one of the ports to be output from the other port, and bypasses the third port and the fourth port in the second transmission unit to allow a packet acquired from one of the ports to be output from the other port. [6] A transmission system comprising a plurality of transmission devices according to any one of claims 1 to 5, wherein a redundant ring-shaped network is formed by the transmission devices. [7] A transmission method to be used by a transmission device in a transmission system including a plurality of transmission devices to form a redundant ring-shaped network, the transmission method comprising: a first step in which a first transmission unit having a first terminal and a second terminal performs control as to whether a packet acquired from one of the terminals is output from the other terminal or output to a connected device; a second step in which a second transmission unit having a third terminal and a fourth terminal performs control as to whether a packet acquired from one of the terminals is output from the other terminal or output to the connected device; a third step in which a bypass control unit performs bypass control to provide bypasses between the terminals of the first transmission unit and between the terminals of the second transmission unit when shutdown failures occur in the first transmission unit and the second transmission unit; and a fourth step in which a packet control unit controls output of packets acquired by the first transmission unit and the second transmission unit in a case where the bypass control is performed in an adjacent transmission device connected via the first port and the third port or via the second port and the fourth port. [8] The transmission method according to claim 7, wherein in the fourth step, the packet control unit discards a packet acquired by the first transmission unit and / or the second transmission unit during the bypass control in the neighboring transmission device in a case where the acquired packet is addressed to a device connected to the neighboring transmission device. [9] The transmission method according to claim 8, wherein in the fourth step, the packet control unit instructs a device to stop transmitting a packet addressed to a same destination as the discarded packet, the device being a transmission source of the discarded packet. [10] The transmission method according to any one of claims 7 to 9, wherein, when the transmission device does not receive a hello packet periodically transmitted from the neighboring transmission device, the packet control unit determines in the fourth step that power-off failures have occurred in the first transmission unit and in the second transmission unit of the neighboring transmission device, and that the bypass control is performed in the neighboring transmission device. [11] A transmission method according to any one of claims 7 to 10, wherein, when power-off failures occur in the first transmission unit and the second transmission unit, the bypass control unit performs the bypass control in the third step such that the bypass control unit bypasses the first port and the second port in the first transmission unit to allow a packet acquired from one of the ports to be output from the other port, and bypasses the third port and the fourth port in the second transmission unit to allow a packet acquired from one of the ports to be output from the other port.

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