JP2020065299A - Communication system - Google Patents

Abstract

To provide a communication system capable of suppressing a load increase caused by the issue of an ARP command, with the suppression of the increase of cost and a labor.SOLUTION: The communication system includes: a server device; a plurality of terminal devices to which communication data is transmitted from the server device in broadcast; an electronic device; and a layer-3 network device which connects the above devices to an identical LAN. The layer-3 network device includes an ARP table storage unit. Each terminal control unit of the plurality of terminal devices answers to the server device and the electronic device, in response to communication which at least includes a content destined to the self-device from the server device. The electronic device includes a processing device including: a list storage unit which stores an IP address list of the terminal devices; and a processing control unit which performs predetermined communication with the plurality of terminal devices at mutually different timings before the lapse of an invalidated period of the ARP table.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a communication system related to signal control between a plurality of electronic devices.

  Signal control communication between electronic devices including a terminal device for driving and controlling a large number of on-site facilities related to railway operation such as traffic lights and turning devices, and a server device for performing overall control according to an operation schedule and operation information There is a system. In this signal control communication system, a signal related to operation control of field equipment is periodically transmitted from the server device to the terminal device. In addition, a response signal is transmitted from the terminal device that receives the signal to the server device. Abnormalities such as non-delivery and delay in the transmission and reception of these signals have a serious influence on railway operation. Therefore, in this signal control communication system, the transmission and reception of signals are constantly monitored (for example, Patent Document 1).

  In this signal control communication system, an IP address is set for each device based on the Internet Protocol (IP), and a command signal output from a server device or a response signal output from a terminal device is transmitted to a layer 3 switch (L3SW) or Some routers transmit the signal to a destination device corresponding to the destination IP address of the signal.

  As IP-based communication, currently, communication using highly reliable TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) communication that does not ensure integrity but has low overhead and high speed are widely used. It is used. In TCP, a MAC (Media Access Control) address or port of a specific communication destination device indicated by an IP address is specified, a transmission route to the transmission destination device is determined, and a communication connection between the transmission and reception devices is established. After that, one-to-one communication is performed. On the other hand, in UDP, data is simply transmitted based on the IP address and port. In addition, UDP is not limited to one-to-one unicast communication, but broadcast or multicast communication in which output data is transmitted to a plurality of destinations at a time is possible.

  Here, in IP communication between electronic devices having different IP addresses, transmission data is transmitted with a header including the IP address of the transmission destination and a header including the MAC address of the transmission destination. If the MAC address corresponding to the IP address is not known, an ARP (Address Resolution Protocol) command containing the IP address of the destination is issued by broadcast from the L3SW or router, and the MAC address is set by the electronic device to which the IP address is set. By returning the address, the correspondence between the IP address and the MAC address is acquired. This correspondence is held in the ARP table in the L3SW until a predetermined expiration time elapses, and if communication is again made to this electronic device before the expiration time elapses, the ARP table is referred to. Communication data is immediately transmitted to the electronic device by the obtained MAC address, the expiration time is extended, the ARP table is maintained in the latest state, and the frequency of issuing unnecessary ARP commands is suppressed. .

  However, when a failure occurs in the communication of the L3SW or the router and the switching or routing operation is transferred to the backup L3SW, or when the operation returns to the main L3SW restored from the backup system, etc. , This ARP table is not held or has been erased, and a new APR command is issued corresponding to all communication destinations and the IP address of the electronic device of the communication destination is added to the ARP table. It is necessary to re-store the correspondence between the MAC address and the MAC address. Therefore, it is necessary to transmit / receive the ARP command for all the required correspondences, and there is a problem that communication is delayed due to the transmission / reception of the ARP command until the ARP table is regenerated.

  On the other hand, in Patent Document 2, a backup of the ARP table generated by the L3SW is maintained in the memory during the failure of the main system, and at the time of restoration, the backup is referred to and communication of the main ARP is sequentially performed while referring to the backup. A technique for preventing communication delay and increase in communication load by updating the table and switching to the latest information is disclosed.

Japanese Patent No. 4948247 Patent No. 5525373

  However, in order to store the backup of the ARP table separately and to update the main ARP table while using the backup, it is necessary to change the configuration and operation of the L3SW, the router, etc., from the conventional one, resulting in cost and labor. There is a problem that it costs.

  An object of the present invention is to provide a communication system capable of suppressing an increase in load caused by issuing an ARP command while suppressing an increase in cost and labor.

In order to achieve the above object, the present invention provides a server device, a plurality of terminal devices that receive communication data transmitted by broadcast from the server device, the server device and the plurality of terminal devices in the same LAN. A communication system comprising: a layer 3 network device to be connected; and one or a plurality of electronic devices connected to the same LAN via the layer 3 network device, wherein the layer 3 network device has an IP address. And a table storage unit that stores correspondence data between the MAC address and the MAC address, and store the newly acquired correspondence data in the table storage unit, and store the correspondence data after the predetermined expiration time has elapsed. A connection control unit that erases the corresponding data, and the plurality of terminal devices are At least an operation control unit that sends back a response to communication data including contents addressed to the own device to the at least one of the electronic devices and the server device, and the electronic device includes a plurality of terminal devices. A list storage unit that stores a list of IP addresses and a plurality of terminal devices based on the list of the list storage unit before the expiration time of the corresponding data related to the plurality of terminal devices has elapsed. And a processing control unit that performs predetermined communication at different timings.
This allows a large number of ARPs to be communicated at one time when communication between the server device and the terminal device requires direct notification to a plurality of terminal devices due to a failure of an electronic device such as a processing device that is not related to the communication itself. Since it is not necessary to send a command, it is possible to prevent an increase in the processing load of the layer 3 network device and an increase in the communication amount of the network. Further, since the command relating to the storage and maintenance of the correspondence data of the IP address and the MAC address in the table storage unit is transmitted from the processing device to each terminal device with the timing shifted from each other, similarly, the processing load of the layer 3 network device is increased. It is possible to suppress an increase in the communication amount of the network, and as a result, it is possible to maintain the communication speed between the server device and the plurality of terminal devices. Since the load can be suppressed and the communication speed can be maintained without changing the configuration and operation of the layer 3 network device, it is possible to suppress an increase in cost and labor.

  Further, the predetermined communication by the processing control unit is issuance of a command related to ICMP_ECHO. That is, the processing control unit uses a basic command for IP connection such as an echo request (request for reachability confirmation) related to ICMP (Internet Control Message Protocol). Therefore, the amount of communication per command is small, and the amount of processing by the terminal device for making a reply is small.

  Further, the processing device is the same as at least one of the electronic devices. Therefore, since the server device and the terminal device are not caused to perform such an operation, it is not necessary to suppress the increase in the processing load of these and it is not necessary to increase the number of unnecessary electronic devices connected, and the cost and the labor for maintenance are not increased. .

  Further, at least one of the electronic devices is a monitoring device for performing processing relating to monitoring of communication abnormality between the server device and the plurality of terminal devices. Therefore, communication safety and reliability can be maintained without significantly increasing the communication load.

Further, the server device is an interlocking device related to on-site equipment including a traffic signal and a turning device in a station, and the operation control unit is connected to the own device based on the communication data addressed to the own device. It was decided to control the operation of the on-site equipment.
Therefore, when the non-delivery notification is sent from the layer 3 network device to each terminal device due to the failure of the third electronic device which is not related to the operation of the on-site facility such as the monitoring device, the layer 3 network device is previously notified. By storing the correspondence data of the MAC address and the IP address of each terminal device in the ARP table storage unit, a large number of ARP commands are not issued at one time, so that a traffic signal or a switch that requires prompt processing can be generated. It does not cause a problem such as delay in the operation of the lever.

  According to the present invention, there is an effect that an increase in load due to the issuance of the ARP command can be suppressed while suppressing an increase in cost and labor.

It is a block diagram showing an embodiment of a communication system of the present invention. It is a chart which shows the issuing timing of the ping command by a monitoring apparatus.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing an overall configuration of a signal control communication system P in a station which is an embodiment of a communication system of the present invention.

  The signal control communication system P (communication system) includes a station device 11, an interlocking device 12 (server device), a monitoring device 13 (electronic device, processing device), a maintenance device 14, and an L3SW 15 (layer 3 network device). , A plurality of terminal devices 16 and a traffic signal 17 and a switch 18 connected to each terminal device 16, respectively.

  The station device 11 includes a control unit 111, and a traffic signal for entering or departing a train (vehicle) at a target station, which is output from a central device (not shown) related to CTC (Centralized Traffic Control) according to operation timetable information or the like. The operation command of 17 and the rolling device 18 is acquired and output to the interlocking device 12.

  The interlocking device 12 includes a control unit 121, and each operation command input from the station device 11 satisfies the logical condition of each of the traffic signals 17 and the switch 18 so that each train or vehicle can travel safely. After determining that it is possible, the operation command is output to the terminal device 16 via the L3SW 15. Further, the interlocking device 12 prohibits an operation that does not satisfy the condition according to various conditions such as the end of the operation corresponding to the output operation command, the lapse of a predetermined time from the operation, and / or the position of the train or the vehicle. Do a lock.

  The terminal device 16 determines whether or not each operation command input from the interlocking device 12 via the L3SW 15 is a command addressed to the device itself, and according to the command addressed to the device itself, the connected traffic signal 17 or rolling signal. An operation controller 161 for operating the container 18 is provided. Further, the terminal device 16 outputs a response signal indicating that the command addressed to the own device has been acquired (or indicates that the acquired command has been further executed) to the interlocking device 12 via the L3SW 15.

  The monitoring device 13 monitors the communication contents between the interlocking device 12 and the terminal device 16, and all the operation commands output from the interlocking device 12 are normally received by the appropriate terminal device 16 and the operation is executed. A predetermined process for determining whether or not there is performed. The monitoring device 13 includes a control unit 131 (processing control unit) and a terminal list 132 (list storage unit). The terminal list 132 stores and holds the IP addresses of all the terminal devices 16 connected to the interlocking device 12 and the monitoring device 13 via the L3SW 15.

  The maintenance device 14 includes a control unit 141, is connected to the L3SW 15 as necessary, and is used for work such as updating of processing software installed in the terminal device 16.

  Each of the station device 11, the interlocking device 12, the monitoring device 13, the maintenance device 14, and the terminal device 16 includes a communication unit including a NIC (Network Interface Card) and the like. A MAC address is defined for each NIC. Further, the IP address is set and held by the control unit of each of these configurations.

  The L3SW 15 relays communication exchanged among the interlocking device 12, the monitoring device 13, the maintenance device 14, and the terminal device 16 on the IP network (network layer), and outputs it to an appropriate destination. The L3SW15 includes an ARP table 151 (ARP table storage unit) that stores the correspondence data between the IP address and the MAC address, and the control unit 152 (connection control unit) of the L3SW15 receives a request for data transmission by unicast communication. In this case, the MAC address corresponding to the IP address of the data transmission destination is confirmed by referring to the ARP table 151. If the MAC address is stored, the header information is rewritten and output, and the MAC address is the ARP table 151. If not stored in, the ARP command for acquiring the MAC address corresponding to the IP address of the data transmission destination is broadcast by UDP. Further, when the control unit 152 receives a request for data transmission by broadcast communication, the control unit 152 outputs the data to all connected devices except the transmission source of the data. Corresponding data of the IP address and the MAC address acquired by the ARP command is stored in the ARP table 151, and if the stored corresponding data is not referenced again within a predetermined expiration time after being acquired. , Will be deleted after the expiration of the expiration time.

  The traffic signal 17 is arranged inside the station and indicates whether or not the train or vehicle can proceed and speed limits (deceleration, speed reduction, etc.). The turning device 18 is installed in the station yard and operates a branching device (point) for switching the traveling direction of a train or a vehicle. Each of the traffic signal 17 and the switch 18 is connected to the corresponding terminal device 16, and the operating state according to the command input from the terminal device 16 is maintained.

  The interlocking device 12 includes other premises equipment (field equipment) related to traveling of a train or a vehicle via the L3SW 15, for example, various equipment related to a railroad crossing, a display control device for a driver or a train user, and the like. Can be connected. Further, the interlocking device 12 is provided with various equipments for acquiring the position of the train, for example, ATS (Automatic Train Stop), ATC (Automatic Train Control) data (such as data from the ground) input and track circuits. It is connected and used for determining logical conditions and locking.

  Next, data transmission / reception between the components in the signal control communication system P of the present embodiment will be described.

  In the signal control communication system P of the present embodiment, as described above, a unique IP address is assigned to each configuration, and signals are exchanged by IP connection within the broadcast domain (same LAN) via the L3SW15. Be seen. Among the exchanged signals, the signal (communication data) transmitted from the interlocking device 12 to each terminal device 16 and the monitoring device 13 during normal operation, that is, the operation command signal is broadcast by UDP without specifying the transmission destination. Is transmitted periodically, for example, every 50 ms.

  The NIC of the terminal device 16 that has received the operation command signal captures each operation command signal and sends it to the control unit, and each control unit causes the operation command signal to operate to the traffic signal 17 or the switch 18 related to the device itself. Determine if it is an instruction. When it is determined to be addressed to the own device, the operation command is executed and the UDP communication related to the operation command signal is answered and transmitted to the interlocking device 12 and the monitoring device 13.

  On the other hand, when communication relating to maintenance work such as updating is performed from the maintenance device 14 to the specific terminal device 16, a TCP connection is established between the specific terminal device 16 and the unicast communication. Is done.

In the signal control communication system P of the present embodiment, the monitoring device 13 refers to the terminal list 132, and at a predetermined interval (for example, every 2 seconds), one device for all the terminal devices 16 in turn (in sequence). A command related to ICMP_ECHO, for example, a ping command is transmitted at different timings. A unicast command is transmitted by ICMP (Internet Control Message Protocol), which is a higher-level protocol of IP, so that the L3SW 15 between the monitoring device 13 and the terminal device 16 that is the transmission target of the ping command is the ping command. When it receives, the ARP table 151 for acquiring the MAC address of the terminal device 16 according to the IP address in the IP packet of the ping command is referred to. When the MAC address is not stored in the ARP table, the L3SW 15 issues the ARP command by broadcast by UDP, and the terminal device 16 makes a reply to acquire the MAC address of the terminal device 16. The L3SW 15 transmits the MAC frame data related to the ping command addressed to the acquired MAC address to the terminal device 16 and also registers the correspondence between the IP address and the MAC address of the terminal device 16 in the ARP table 151.
At this time, by setting the transmission interval such that the ping transmission interval for the predetermined terminal device 16 is equal to or less than the expiration time of the ARP table 151, the MAC address once stored in the ARP table 151 is not erased, so that It is not necessary to issue the ARP command for the second time and thereafter.

FIG. 2 is a chart showing the issuing timing of the ping command by the monitoring device 13.
The monitoring device 13 sequentially transmits the ping command to each terminal device 16 so that the state in which the correspondence between the IP address and the MAC address of all the terminal devices 16 is stored in the ARP table 151 is maintained. That is, the ping command issuance interval by the monitoring device 13 is set to be a time obtained by dividing the expiration time of the ARP table 151 in the L3SW 15 by a predetermined margin by the number of terminal devices 16, and thus the ping command is issued. The correspondence between the IP addresses and the MAC addresses of all the terminal devices 16 continues to be stored in the ARP table 151 while minimizing the increase of traffic in the network and the load of the L3SW 15. Therefore, the ping command is immediately transmitted to each terminal device 16 according to the ARP table 151, and the ARP command is not issued.

  If the number of terminal devices 16 is sufficiently small with respect to the expiration time of the ARP table 151, the ping command does not necessarily need to be issued at equal time intervals, and traffic and load on the L3SW 15 increase. After issuing the ping command to all the terminal devices 16 at a time interval that does not adversely affect, the next ping command is issued to each terminal device 16 until a predetermined time equal to or less than the expiration time of the ARP table 151 elapses. You may cancel.

  In this situation, if an abnormality occurs in the communication path between the monitoring device 13 or the L3SW 15 and the monitoring device 13 and the response of the input command from each terminal device 16 does not reach the monitoring device 13, the L3SW 15 determines that each terminal device 16 To the respective destinations, the ICMP notification relating to the undelivered destination is performed. At this time, since the correspondence relationship between the MAC address and the IP address of each terminal device 16 is all stored in the ARP table 151, the control unit 152 of the L3SW 15 refers to the ARP table 151 without issuing an ARP command. The destination MAC address and the destination IP address in the header are set to the terminal device 16 and the ICMP notification is transmitted.

As described above, the signal control communication system P according to the present embodiment includes the interlocking device 12, the plurality of terminal devices 16 that receive the communication data broadcast from the interlocking device 12, the interlocking device 12, and the plurality of terminal devices. Signal control communication including L3SW15 connecting 16 in the same LAN, and one or a plurality of electronic devices such as monitoring device 13 connected in the same LAN as interlocking device 12 and terminal device 16 via L3SW15 In the system P, the L3SW 15 stores the corresponding data of the IP address and the MAC address in the ARP table 151, the newly acquired corresponding data in the ARP table 151, and after the corresponding data is stored. And a control unit 152 that erases the corresponding data after a lapse of a predetermined expiration time. The device 16 includes an operation control unit 161 that sends a reply to the interlocking device 12 and the monitoring device 13 for communication data including at least the contents addressed to itself from the interlocking device 12, and the electronic device includes a plurality of terminals. The terminal list 132 that stores the list of IP addresses of the devices 16 and the terminal devices that are stored in the terminal list 132 before the expiration time of the corresponding data of the IP address and the MAC address of the plurality of terminal devices 16 respectively elapses. The monitoring device 13 includes a control unit 131 that transmits a ping command to the plurality of terminal devices 16 based on the list of 16 at different timings.
That is, in contrast to the communication between the interlocking device 12 and the terminal device 16 which are being communicated by UDP in order to maintain high-speed communication, a plurality of terminals are damaged due to a failure of the monitoring device 13 not related to the communication itself. By generating and maintaining the ARP table 151 in advance when direct notification to the device 16 is required, it is not necessary to send an ARP command, and the processing load of the L3SW 15 due to unintended mass issue of ARP and network communication. The increase in quantity can be prevented. Further, since commands relating to the generation and maintenance of the ARP table 151 are managed so as to be transmitted from the monitoring device 13 to the respective terminal devices 16 at timings different from each other, the L3SW 15 is also controlled at the time of generation and maintenance of the ARP table 151. It is possible to suppress an increase in processing load and communication amount of the network, and as a result, it is possible to maintain the communication speed between the interlocking device 12 and the plurality of terminal devices 16. Moreover, since the ping is transmitted from one monitoring device 13 to each terminal device 16, it is possible to easily perform the operation management for shifting the transmission timing. Since the load can be suppressed and the communication speed can be maintained without changing the configuration and the processing of the L3SW 15, it is possible to suppress the increase in cost and labor.

  Further, since the monitoring device 13 transmits a command related to ICMP_ECHO, particularly ping, the communication amount per command is small, and the processing of the terminal device 16 for making a reply is small, so that a large load does not occur.

Also, since the ping is transmitted from the monitoring device 13 to each terminal device 16 in a batch, the best command transmission is performed so that the processing load of the L3SW 15 and the network load between the interlocking device 12 and each terminal device 16 do not increase. The interval can be easily set.
Further, since the interlocking device 12 is not allowed to perform such an operation, the interlocking device 12 does not increase the processing load of the interlocking device 12, and the interlocking device 12 can more reliably output the operation command related to the signal control at an appropriate timing. I can.
Further, conventionally, since the device used as the monitoring device 13 is made to perform both the ping transmission operation and its timing control, it is not necessary to increase the number of unnecessary electronic devices connected, and the cost and maintenance work are not increased.

  Further, since the monitoring device 13 is connected to the inside of the LAN including the interlocking device 12 and the plurality of terminal devices 16, the load on the monitoring device 13 due to the communication abnormality can be suppressed, so that the communication load can be greatly increased. It is possible to maintain the safety and reliability of communication without having to do so. In particular, it is possible to easily achieve both the reduction of communication overhead due to the use of UDP communication and the countermeasure against the deterioration of communication safety.

  In addition, in particular, a signal is transmitted between the interlocking device 12 related to the operation control of the on-site equipment including the traffic signal 17 and the switch 18 in the station yard, and the terminal device 16 that actually controls the operation of the on-site equipment. In the case where the non-delivery notification is sent from the L3SW 15 to each terminal device 16 due to the failure of the third electronic device that is not related to the operation of the on-site facility such as the monitoring device 13, the L3SW 15 is previously notified of the ARP table. By keeping the correspondence between the MAC address and the IP address of each terminal device 16 in large numbers, it is possible to avoid issuing a large number of ARP commands at one time. It does not cause a problem such as a delay in the operation of the lever 18 or the like.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above embodiment, ping is described as a command related to ICMP_ECHO, but other commands such as tracer (traceroute) may be used, and other unicast commands that require address resolution for transmission may be used. Other commands may be used as long as the processing load is sufficiently small.

  Further, the L3SW 15 may be a router as long as all the components are provided in the same LAN, that is, within a range where the broadcast message can reach.

  Further, in the above-described embodiment, both the signal non-delivery target and the ping command are issued from the monitoring device 13, but it is possible to store a list of IP addresses of the terminal device 16. If there is a computer connected to the L3SW 15 for a time that does not affect the issuance of the ping command to all the terminal devices 16, the ping command may be issued from the computer.

  Further, the device to which the response is input from each terminal device 16 is not limited to the monitoring device 13. It may be another information processing device or the like that sorts input response data and processes it. Further, the number of monitoring devices 13 and information processing devices provided in the same LAN is not limited to one, and may be multiple. In this case, the device to which a reply is input from each terminal device 16 and the device that sends a ping to each terminal device 16 may be different.

Further, in the above-described embodiment, the signal control communication system P related to the operation control of the traffic signal 17 and the switch 18 in the station is described, but the signal control system related to the crossing between stations, the switch and the block signal. The present invention may be applied to, for example, and may be applied to any system that performs similar communication control.
In addition, the specific details such as the configuration, the arrangement, the circuit, and the processing procedure shown in the above-described embodiment can be appropriately changed without departing from the spirit of the present invention.

11 station device 111 control unit 12 interlocking device 121 control unit 13 monitoring device 131 control unit 132 terminal list 14 maintenance device 141 control unit 15 L3SW
151 ARP table 152 control unit 16 terminal device 161 operation control unit 17 traffic signal 18 switch P signal control communication system

In order to achieve the above object, the present invention receives communication data transmitted from a server device and the server device by broadcasting at predetermined time intervals regarding the operation of the on-site equipment related to railway operation, and stores the on- site equipment. A plurality of terminal devices to be operated , a layer 3 network device connecting the server device and the plurality of terminal devices in the same LAN, and one or more connected in the same LAN via the layer 3 network device A communication system including a plurality of electronic devices, wherein the layer 3 network device stores a table storage unit that stores correspondence data between IP addresses and MAC addresses, and stores the newly obtained correspondence data in the table storage unit. Of the correspondence data, and after the corresponding expiration date has passed since the correspondence data was stored, A connection control unit for erasing data, wherein the plurality of terminal devices are connected to at least one of the electronic devices and the server device for communication data including contents addressed to at least the own device from the server device. The electronic device includes an operation control unit that replies to the electronic device, the electronic device includes a list storage unit that stores a list of IP addresses of the plurality of terminal devices, and the expiration time of the correspondence data related to the plurality of terminal devices. for a period shorter respectively, and it may include the processing device and a processing control unit for each at different timings performing predetermined communication with respect to the plurality of terminal devices based on the list of the list storage unit.
This allows a large number of ARPs to be communicated at one time when communication between the server device and the terminal device requires direct notification to a plurality of terminal devices due to a failure of an electronic device such as a processing device that is not related to the communication itself. Since it is not necessary to send a command, it is possible to prevent an increase in the processing load of the layer 3 network device and an increase in the communication amount of the network. Further, since the command relating to the storage and maintenance of the correspondence data of the IP address and the MAC address in the table storage unit is transmitted from the processing device to each terminal device with the timing shifted from each other, similarly, the processing load of the layer 3 network device is increased. It is possible to suppress an increase in the communication amount of the network, and as a result, it is possible to maintain the communication speed between the server device and the plurality of terminal devices. Since the load can be suppressed and the communication speed can be maintained without changing the configuration and operation of the layer 3 network device, it is possible to suppress an increase in cost and labor.
Also, the processing control unit performs the predetermined communication with the plurality of terminal devices at a time interval obtained by dividing a time obtained by subtracting a predetermined margin from the expiration time by the number of the plurality of terminal devices.
Further, the processing control unit performs the predetermined communication with the plurality of terminal devices at transmission intervals set to perform communication at the different timings.

Claims (5)

A server device,
A plurality of terminal devices that receive communication data transmitted by broadcast from the server device,
A layer 3 network device that connects the server device and the plurality of terminal devices in the same LAN;
One or more electronic devices connected to the same LAN via the layer 3 network device;
A communication system comprising:
The layer 3 network device is
A table storage unit that stores correspondence data between IP addresses and MAC addresses;
A connection control unit that stores the newly acquired correspondence data in the table storage unit, and that deletes the correspondence data after a predetermined expiration time has elapsed after storing the correspondence data,
Equipped with
Each of the plurality of terminal devices includes an operation control unit that replies to at least one of the electronic devices and the server device with respect to communication data including contents addressed to at least the own device from the server device,
The electronic device includes
A list storage unit that stores a list of IP addresses of the plurality of terminal devices;
A process control for performing predetermined communication with the plurality of terminal devices at different timings based on the list of the list storage unit before the expiration time of the corresponding data of the plurality of terminal devices respectively elapses. Department,
A communication system including a processing device including:   The communication system according to claim 1, wherein the predetermined communication by the processing control unit is issuance of a command related to ICMP_ECHO.   The communication system according to claim 1, wherein the processing device is the same as at least one of the electronic devices.   The at least one of the electronic devices is a monitoring device for performing processing relating to monitoring of communication abnormality between the server device and the plurality of terminal devices. The communication system according to any one of claims. The server device is an interlocking device related to a field facility including a traffic signal and a turning device in a station,
The operation control unit controls the operation of the on-site facility connected to the self-device based on the communication data addressed to the self-device. The operation control unit according to claim 1, wherein Communications system.

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