COMMUNICATION DEVICE, COMMUNICATION DEVICE CONTROL METHOD, COMMUNICATION SYSTEM, AND PROGRAM

Abstract

To make communication work in a network regardless of the state of a communication device connected to the network.SOLUTION: A communication device has: a first communication interface for a first transmission line; a second communication interface for a second transmission line; a control unit that controls a communication path of a signal received by the first communication interface in the communication device; and a processing unit that executes predetermined processing on the received signal. When the communication device is in a first state, the control unit outputs the received signal to the second communication interface through the processing unit, and when the communication device is in a second state, outputs the received signal to the second communication interface not through the processing unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a control technique for a communication device connected to a network. [Background technology]

[0002] A star topology is known as a typical connection form (topology) in a communication network. However, depending on the installation environment and operating conditions, a daisy chain topology such as a ring topology or a line topology may be used for connection. For example, Patent Document 1 discloses a railway vehicle information transmission device equipped with multiple terminal devices, in which the terminal devices are connected using a line topology. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-103588 Summary of the Invention [Problem to be solved by the invention]

[0004] In a line topology network such as that disclosed in Patent Document 1, all connected communication devices must be operational. Therefore, if some of the connected communication devices go into a standby state (failure state / sleep state) and some of their functions are restricted, other communication devices connected beyond the communication device may be unable to communicate. This may significantly reduce the availability of the entire network system.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to enable communication in a network to function even when a communication device connected to the network is in a standby state (failure state / sleep state). [Means for solving the problem]

[0006] As one means for achieving the above object, a communication device of the present invention has the following configuration: A communication device including a first communication interface for a first transmission path, a second communication interface for a second transmission path, a control unit for controlling a communication path in the communication device for a signal received by the first communication interface, and a control unit for controlling a state of the communication device by: No. State 1 and No. a state control unit that controls the communication device to transition to one of a plurality of states including state 2, and when the communication device is in the second state and a magic packet is received by the first communication interface, switches the communication path within the communication device to transition the state of the communication device to the first state; and a processing unit that performs predetermined processing on the received signal, wherein the control unit controls the communication device to output the received signal to the second communication interface via the processing unit when the communication device is in the first state, and to output the received signal to the second communication interface without going through the processing unit when the communication device is in the second state. [Effects of the Invention]

[0007] According to the present invention, it is possible to make communication on a network function regardless of the state of a communication device connected to the network. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 shows an example of the configuration of a network system according to an embodiment. [Figure 2] FIG. 2 shows an example of the configuration of a node (communication device) according to the embodiment. [Figure 3] FIG. 3 is a conceptual diagram illustrating the state transition of a node according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating a communication path of a signal in a node in an active state. [Figure 5] FIG. 5 is a diagram illustrating a communication path of a signal in a node in a standby state. [Figure 6] FIG. 6 is a conceptual diagram illustrating the connection state between a plurality of nodes. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, with reference to the accompanying drawings, a detailed description will be given of an embodiment for carrying out the present invention. Note that the embodiment described below is an example of a means for realizing the present invention, and should be appropriately modified or changed depending on the configuration of the device to which the present invention is applied and various conditions. The present invention is not limited to the following embodiment. Furthermore, not all of the combinations of features described in the present embodiment are necessarily essential to the solution of the present invention.

[0010] [Network system configuration] 1 shows an example of the configuration of a network system (communication system) according to this embodiment. This network system includes nodes (communication devices) 101-1 to 101-n (n>1) connected in a line, a server device 102, a system controller device 103, and a switch device 104. In the following description, the nodes 101-1 to 101-n may be collectively referred to as node 101.

[0011] 1, the side of the node 101 that is closer to the switch device 104 is called the root side, and the side that is farther from the switch device 104 is called the leaf side. As will be described later with reference to FIG. 2, the node 101 has two PHY units 202 and 205 as input / output units, and can be connected to other nodes 101. This makes it possible to arrange and connect any number of nodes 101 in a line. The node 101-1 closest to the root is connected to the switch device 104. The node 101-n closest to the leaf is connected only to the node immediately before it, and therefore only needs to be provided with one input / output unit.

[0012] The switch device 104 has a function of switching the network by connecting to the server device 102, thereby enabling each of the nodes 101 to communicate with the server device 102. In addition, the system controller device 103 manages and monitors the nodes 101. As will be described later with reference to FIG. 2, the node 101 includes a sensor unit 213 and a state control unit 212, which the system controller device 103 can control.

[0013] [Node Configuration] 2 shows an example of the configuration of a node (communication device) 101 according to this embodiment. The node 101 shown in FIG. 2 is connected to a first transmission path 201 on the root side and a second transmission path 204 on the leaf side. The node 101 has two PHY units, a first PHY unit 202 and a second PHY unit 205, as input / output units. The first PHY unit 202 and the second PHY unit 205 are configured to perform transmission and reception processing corresponding to the physical layer of the OSI (Open System Interconnection) reference model. For example, the first PHY unit 202 and the second PHY unit 205 are configured to perform transmission and reception processing corresponding to the physical layer of Ethernet (registered trademark). The first PHY unit 202 and the second PHY unit 205 are connected to a system control unit 216 via a first I / F unit 203 and a second I / F unit 206, respectively. The system control unit 216 is configured using an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The first I / F unit 203 and the second I / F unit 206 are configured to transmit and receive data to and from the first PHY unit 202 and the second PHY unit 205, respectively. In this embodiment, the first PHY unit 202 and the first I / F unit 203 are referred to as a first communication interface for the first transmission path 201, and the second PHY unit 205 and the second I / F unit 206 are referred to as a second communication interface for the second transmission path 204. The configuration of the first communication interface and the second communication interface is not limited to this, and may be any configuration that functions as an input / output unit for each transmission path and is connectable to a processing unit 211, which will be described later.

[0014] The bypass control unit 207 controls the communication path of signals in the node 101. Specifically, the bypass control unit 207 performs control to switch between the first path and the second path. The first path is a path (detour path) that directly connects the first communication interface (the first PHY unit 202 and the first I / F unit 203 in this embodiment) and the second communication interface (the second PHY unit 205 and the second I / F unit 206 in this embodiment). The second path is a path that connects the first communication interface to the second communication interface at least via the processing unit 211. In this embodiment, the second path connects the first communication interface to the first MAC unit 208 and connects the second communication interface to the second MAC unit 209, thereby enabling connection to the state control unit 112 and the processing unit 211 via the interconnect unit (210). Since the processing unit 211 performs protocol processing (processing by an upper layer), the first route is a route that does not go through the processing unit 211, and the second route is a route that goes through the processing unit 211. The bypass control unit 207 can switch the path in this way under the control of the state control unit 212. The state control unit 212 may be disposed outside the system control unit 216.

[0015] When connected to the first I / F unit 203, the first MAC unit 208 is configured to execute processing corresponding to the MAC sublayer of the data link layer of the OSI reference model for the first transmission path 201. When connected to the second I / F unit 206, the second MAC unit 209 is configured to execute processing corresponding to the MAC sublayer of the data link layer of the OSI reference model for the second transmission path 204.

[0016] Interconnect unit 210 is configured to be able to interconnect first MAC unit 208, second MAC unit 209, processing unit 211, and state control unit 212. The processing unit 211 is configured, for example, with one or more CPUs (Central Processing Units), and performs various controls of the node 101. The processing unit 211 can execute various control programs to perform the controls. The processing unit 211 can also perform predetermined protocol processing (processing by an upper layer) on signals received via the interconnect unit 110. Some or all of the digital domain processing in the system control unit 216 may be performed by the processing unit 211 executing software (programs).

[0017] The state control unit 212 controls and manages state transitions of the node 101. Possible states of the node 101 will be described later with reference to FIG. 3. The state control unit 212 can control and manage state transitions of the node 101 based on input information from the sensor unit 213 and the first PHY unit 102. Although not shown in FIG. 2, the second PHY unit 205 may be connected to the state control unit 212, and the state control unit 212 may control and manage state transitions of the node 101 based on input information from the second PHY unit 205. Furthermore, the state control unit 212 can control the bypass control unit 207 and the power control unit 214 depending on the state of the node 101.

[0018] The sensor unit 213 performs various monitoring processes such as system monitoring and environmental monitoring for the node 101. For example, the sensor unit 213 has a watchdog function and can monitor whether the processing unit 211 and the system control unit 216 are operating normally (system monitoring). The sensor unit 213 can also monitor the ambient temperature and the voltage of the power supply 215 (environment monitoring). The sensor unit 213 can detect an abnormality in the node 101 through such monitoring processing. Furthermore, in this embodiment, when the sensor unit 213 detects an abnormality, it can determine whether the abnormality is an abnormality that makes communication impossible via the second path, or an abnormality that makes communication impossible via both the first and second paths. An abnormality that makes communication impossible via the second path is, for example, an abnormality in which a hardware error occurs in the system control unit 216, causing the processing unit 211 to not operate normally. An abnormality that makes communication impossible via the first and second paths is an abnormality in which the system control unit 216 suspects that an electronic component or the like has failed due to a temperature rise or impact, and it is necessary to immediately shut off the power supply. When the sensor 213 detects an abnormality, it notifies the state control unit 212 of the determination result as to whether the abnormality is such that communication is impossible on the second path or such that communication is impossible on both the first and second paths.

[0019] The power control unit 214 supplies power to each unit in the node 101 using power supplied from the power supply 215 or the like. The power control unit 214 supplies power to each unit in the node 101, including the system control unit 216, under the control of the state control unit 212. Note that although the power supply 215 is shown in FIG. 2, power may be supplied from outside the node 101. Furthermore, although not shown in FIG. 2, a clock is also supplied to each unit in the node 101 while the power control unit 214 is supplying power to each unit in the node 101.

[0020] [State transition of node 101] Next, the state transition of the node 101 will be described with reference to Fig. 3. Fig. 3 is a conceptual diagram illustrating the state transition of the node 101 according to this embodiment. As described above, the states of the node 101 are the power-off state S0, the startup state S1, the standby state S2, and the abnormality detection state S3.

[0021] The power-off state S0 is a power-off state in which power is not supplied (stopped) to the node 101 by the power control unit 214. In the power-off state S0, when power is supplied to the node 101 by the power control unit 214 and startup is completed, the state of the node 101 transitions to the startup state S1 (transition 302). In the startup state S1, power and a clock are supplied to each unit within the node 101.

[0022] The communication path of a signal in the node 101 in the active state S1 will be described with reference to Fig. 4. Fig. 4 is a diagram illustrating the communication path of a signal in the node 101 in the active state S1. 4, in the startup state S1, a signal received by the first PHY unit 202 from the first transmission path 201 is processed by the first MAC unit 208 via the bypass control unit 207. The signal processed by the first MAC unit 208 is further transported to the processor 212 or the state control unit 212 via the interconnect unit 210 and processed there. Furthermore, the signal processed by the second MAC unit 209 is transmitted by the bypass control unit 207 to another node 101 on the leaf side via the second PHY unit 205 and the second transmission path 204. The same applies when the second PHY unit 205 receives a signal from the second transmission path 204, and the received signal is processed via the second MAC unit 209 and the first MAC unit 208.

[0023] The node 101, which is in the active state S1, does not receive a signal from the first transmission path 201 or the second transmission path 204 for a predetermined period of time. Alternatively, the processing unit 211 or the state control unit 212 instructs the node 101 to transition to the standby state S2 (transition 303). The state control unit 212 may transition the node 101 to the standby state S2 when it receives a signal to transition to the standby state S2 via the first PHY unit 202 or the second PHY unit 205. The state control unit 212 may also transition the node 101 to the standby state S2 when no processing operation by the processor 111 is confirmed for a predetermined period of time. In this way, the trigger for transitioning the node 101 to the standby state S2 is not limited to a specific trigger. Furthermore, the state control unit 212 can transition the state of the node 101 from the standby state S2 to the power-off state S0 (transition 302) when it receives a signal for transitioning to the power-off state S0 via, for example, the first PHY unit 202 or the second PHY unit 205. This transition is also not limited to a specific trigger. Furthermore, as will be described later, in response to the node 101 in the startup state S1 detecting an abnormality, the state control unit 212 transitions the state of the node 101 to the abnormality detection state S3 (transition 308). The abnormality is detected by the sensor unit 213. In the abnormality detection state S3, it is determined whether the abnormality is an abnormality that makes communication impossible over the second path, or an abnormality that makes communication impossible over both the first and second paths. If it is determined that the abnormality makes communication impossible over the second path, the state transitions to the standby state S2 (transition 307). If it is determined that the abnormality makes communication impossible over the first and second paths, the state transitions to the power-off state S0 (transition 306).

[0024] In the standby state S2, the node 101 is in a state in which the functions of the processing unit 211 and some of the communication functions are restricted. The communication path of signals in the node 101 in the standby state S2 will be described with reference to Fig. 5. Fig. 5 is a diagram illustrating the communication path of signals in the node 101 in the standby state S2.

[0025] In the standby state S2, the state control unit 212 controls the bypass control unit 207 as follows: The state control unit 212 controls the bypass control unit 207 to transfer signals received by the first PHY unit 202 from the first transmission path 201 to the second PHY unit 205, and to transfer signals received by the second PHY unit 205 from the second transmission path 204 to the first PHY unit 202. In this embodiment, this type of operation of node 101 is referred to as a repeater operating state. When node 101 enters the repeater operating state, first MAC unit 208, second MAC unit 209, interconnect unit 210, and processing unit 211 no longer need to operate. That is, a signal received by first PHY unit 202 is output to second PHY unit 205 without passing through processing unit 211, and a signal received by second PHY unit 205 is output to first PHY unit 203 without passing through processing unit 211. This enables node 101 to transmit a signal received on one transmission path to the other transmission path.

[0026] Next, the transition of the node 101 from the standby state S2 to the active state S1 will be described. In the node 101 in the standby state S2, a signal received by the first PHY unit 202 or the second PHY unit 205 is not conveyed to the processing unit 211, and therefore the content of the signal is not analyzed. On the other hand, the first PHY unit 202 or the second PHY unit 205 can receive (detect) the signal. In this embodiment, when the first PHY unit 202 or the second PHY unit 205 receives (detects) a predetermined signal, it notifies the state control unit 212 that the signal has been received. This causes the state control unit 212 to transition the state of the node 101 from the standby state S2 to the active state S1 (transition 304).

[0027] An example of the predetermined signal is a Magic Packet (registered trademark). The Magic Packet is a packet for remotely activating a device that supports Wake On LAN (registered trademark) (has a Wake On LAN function). If the node 101 is a Wake On LAN-compatible device, receiving this Magic Packet allows the node 101 to transition from a standby state S2 to an activated state S1. Referring to FIG. 1, the magic packet can be transmitted by the server device 102, the system controller device 103, or another node 101 connected to the first PHY unit 202. In this way, the node 101 in the standby state S2 is in a repeater operating state, and therefore cannot perform protocol processing by the processing unit 211. However, when a predetermined signal is received (detected), the state control unit 212 can transition the state of the node 101 from the standby state S2 to the active state S1. The processing unit 211 may control the node 101 to transition from the standby state S2 to the active state S1 at any timing.

[0028] In the startup state S1, the state control unit 212 can transition the state of the node 101 from the startup state S1 to the power-off state S0 (transition 301) when it receives a signal for transitioning to the power-off state S0 via, for example, the first PHY unit 202 or the second PHY unit 205. Note that the state of the node 101 may be transitioned from the startup state S1 to the power-off state S0 at any timing under the control of the processing unit 211.

[0029] Next, we will explain the state control of node 101 when the sensor unit 213 detects an abnormality in node 101 in startup state S1. As described above, the sensor unit 213 performs various monitoring processes such as system monitoring and environmental monitoring for node 101, and detects an abnormality. Upon receiving a notification of abnormality detection from the sensor unit 213, the state control unit 212 transitions to abnormality detection state S3 (transition 308).

[0030] The abnormality detection state S3 is a state in which it is determined what type of abnormality has been detected by the sensor unit 213. It is determined whether the abnormality is an abnormality that makes communication impossible via the second path, or an abnormality that makes communication impossible via both the first and second paths. If it is determined that an abnormality has occurred that makes communication impossible over the second path, the state transitions to standby state S2 (transition 307). On the other hand, if it is determined that an abnormality has occurred that makes communication impossible over the first and second paths, the state transitions to power-off state S0. At this time, the state control unit 212 determines whether the sensor unit 213 has detected an abnormality. When the node 101 transitions to the standby state S2 (transition 307), the node 101 operates as a repeater, so that the function of the network system is maintained. In this case, the system controller device 103 may perform control so as to restart the network system including the node 101. On the other hand, when the node 101 transitions to the power-off state S0 (transition 306), the state control unit 212 forcibly cuts off the power supply to the node 101 to stop its function. In this case, communication with other nodes 101 connected to the leaf side of the node 101 is also stopped.

[0031] Next, the connection state of nodes 101-1 to 101-n according to this embodiment, which operate by configuring a line-shaped network, will be described with reference to Fig. 6. Fig. 6 is a conceptual diagram illustrating the connection state between a plurality of nodes according to this embodiment. Fig. 6 shows a conceptual diagram of the connection state when node 101-3 in the network system shown in Fig. 1 is in one of the three states described with reference to Figs. 3 to 5, and the other nodes (nodes 101-1 to 101-2, 101-4 to 101-n) are in the active state S1. Figs. 6(a) to 6(c) correspond to the connection states when node 101-3 is in the active state S1, the power-off state S0, and the standby state S2, respectively.

[0032] 6(a) shows a connection state when all of the nodes 101 (nodes 101-1 to 101-n) including node 101-3 are in the startup state S1. Since all of the nodes 101 are in the startup state S1, connections are possible for communications between all of the nodes 101 and between the server device 102 and the nodes 101. The communication path of signals in node 101-3 is the path shown in FIG. 4, and signals received by the first PHY unit 202 of node 101-3 are processed by the processing unit 211 and the like and transferred to the subsequent node 101-4 via the second PHY unit 205.

[0033] 6(b) shows the connection state when node 101-3 is in power-off state S0. In this case, in node 101-3, power supply to processing unit 211, interconnect unit 210, first MAC unit 208, and second MAC unit 209 is cut off, and communication processing within node 101-3 is stopped. As a result, signals are not transmitted to nodes 1101-4 to 1101-n connected to the leaf side of node 101-3.

[0034] 6(c) shows the connection state when node 101-3 is in standby state S2. In this case, bypass control unit 207 conveys the signal received by first PHY unit 202 to second PHY unit 205, causing node 101-3 to enter a repeater operating state. That is, although protocol processing by processing unit 211 is not possible in node 101-3, node 101-3 entering the repeater operating state enables communication relay. As a result, nodes 101-4 to 101-n connected to the leaf side of node 101-3 can continue communication.

[0035] Thus, according to this embodiment, in a network system in which multiple nodes (communication devices) are arranged in a line, a node in a standby state transitions to repeater operation. This allows nodes connected further away from the node (nodes on the leaf side of the node) to continue communication in the network, providing a network system with improved availability. Note that, although this embodiment has been described with respect to nodes connected in a line, the same description can also be applied to nodes connected in a ring (loop) shape.

[0036] While the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications and changes are possible within the scope of the present invention. For example, the present invention can be embodied as a system, an apparatus, a method, a program, a recording medium (storage medium), etc.

[0037] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions. [Explanation of symbols]

[0038] 101 (101-1 to 101-n): Node (communication device), 102: Server device, 103: System controller device, 104: Switch device

Claims

1. A communication device, a first communication interface for the first transmission line; a second communication interface for the second transmission line; a control unit that controls a communication path in the communication device for a signal received by the first communication interface; a processing unit that performs predetermined processing on the received signal; Controlling the state of the communication device to transition to one of a plurality of states including a first state and a second state; a state control unit that, when the communication device is in the second state and a magic packet is received by the first communication interface, transitions the state of the communication device to the first state by switching a communication path within the communication device; and A communication device characterized in that the control unit controls the communication device to output the received signal to the second communication interface via the processing unit when the communication device is in the first state, and to output the received signal to the second communication interface without going through the processing unit when the communication device is in the second state.

2. a sensor unit that detects an abnormality in the communication device; The communication device according to claim 1 , wherein the state control unit controls the state of the communication device based on an abnormality detected by the sensor unit.

3. When the communication device is in an activated state, the sensor unit determines whether the abnormality is an abnormality within the communication device; 3. The communication device according to claim 2, wherein when the sensor unit detects an abnormality inside the communication device, the state control unit transitions the state of the communication device to the second state.

4. The communication device according to claim 2 or 3, characterized in that when the sensor unit detects an irrecoverable abnormality, the state control unit transitions the state of the communication device to a third state in which power supply to the communication device is stopped.

5. 5. The communication device according to claim 2, wherein the state control unit controls the state of the communication device based on a signal received by the first communication interface.

6. A communication system having a plurality of communication devices connected in a line or ring configuration, A communication system, wherein each of the plurality of communication devices is a communication device according to any one of claims 1 to 5.

7. 6. The communication device according to claim 1, wherein the first state is a running state, and the second state is a standby state.

8. 1. A method for controlling a communication device having a first communication interface for a first transmission path and a second communication interface for a second transmission path, comprising: a state control unit controls the state of the communication device to transition to one of a plurality of states including a first state and a second state; a state control unit step of, when the communication device is in the second state and a magic packet is received by the first communication interface, switching a communication path within the communication device to transition the state of the communication device to the first state; a first control step in which the state control unit performs predetermined protocol processing on a signal received by the first communication interface when the communication device is in the first state, and controls the signal after the predetermined protocol processing to be output to the second communication interface; a second control step in which the state control unit controls the received signal to be output to the second communication interface without performing the specified protocol processing on the received signal when the communication device is in the second state.

9. A computer program for causing a computer to execute the communication device control method according to claim 8.

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