JP5651878B2 - Fault monitoring system - Google Patents

Description

  The present invention relates to a failure monitoring system suitable for application to monitoring a failure of a network relay device that relays a frame transmitted and received by a computer device (hereinafter abbreviated as “computer”) to a network.

  Conventionally, in a control system that requires high reliability such as a network between stations, in order to realize the high-reliability control, the control computer is duplicated, and there is also a network that connects the control computer. Sometimes it was doubled. In general, data used in the network layer is referred to as a packet, and data used in the data link layer is referred to as a frame. However, in the following description, a packet and a frame have the same meaning and are treated as “frame” in a unified manner.

  If the networks are duplicated, even if a failure occurs in one network and data cannot be transmitted / received, the operation of the control system can be continued by switching to the other network and transmitting / receiving data. Such a duplex network system is composed of a duplex network, a network connection device connected to each duplex network and performing data input / output, and a network connection device connected to the network connection device. The network relay device relays the frame to the connected computer.

  The duplex network system performs the following operations. That is, the network relay apparatus connected to the transmission source computer that transmits the frame transmits two identical frames to the duplexed network connection apparatus. Each of the duplexed network connection devices transmits the same frame to the duplex network.

  When the duplex destination network connection apparatus receives a frame from the duplex network, it transmits the frame to the destination network relay apparatus. Here, the destination network relay apparatus relays the earliest arrived frame to the destination computer, attaches the same communication number as the frame already relayed to the destination computer, and discards the later arrived frame. As described above, the network relay device performs control so that the destination computer does not receive a duplicate frame by selecting whether the frame arrived from another device is to be relayed or discarded.

  The duplex network system is employed in the construction of an industry that requires high reliability, for example, a plant control system, in addition to the above-described inter-station network. And in order to implement | achieve a duplex network system, the technique as disclosed in the following patent documents 1 has been examined.

  Patent Document 1 discloses a technique for monitoring a failure in data communication in a communication system based on whether or not a check response message is returned in response to a check request message transmitted to a slave line switching device.

JP 2003-273930 A

  By the way, when a failure occurs in one of the duplicated computers, it is required to switch to the other computer to transmit / receive frames. Here, when only one network relay device is set and a failure occurs in this network relay device, the computer cannot transmit / receive frames to / from other computers via the network. For this reason, it has been studied to duplicate the network relay device. However, as described above, when receiving the same frame from the duplicated network, the network relay device relays the first-arrived frame and discards the later-arrived frame. Therefore, if the duplicated network relay devices operate independently, the frames relayed by each network relay device may be the same, and the computer may receive the same plurality of frames.

  In order to avoid such a situation, the duplicated network relay apparatus sets a master-slave relationship in which one is a master and the other is a slave. However, simply maintaining the master-slave relationship of the network relay device may take time to take over the processing to the slave network relay device when a failure occurs in the master network relay device. It was.

  The present invention has been made in view of such a situation, and monitors a failure of a duplexed network relay device so that a failure occurring in the network relay device does not affect frame transmission / reception. Objective.

  The present invention is connected to a duplex computer device for transmitting and receiving frames and a duplex computer device, respectively, and transmits a frame received from the computer device by branching to a plurality of routes. A duplexed two-branch connection device that transmits a received frame to a computer device, and another duplexed network connected to a duplexed network by relaying a frame received from the two-branch connection device A duplex network relay device that relays a frame transmitted to another relay device and received from another duplex network relay device via the network to a two-branch connection device, and a network relay device connected to the network Frames received from the network are sent to the network, and frames received from the network are duplicated. A duplex network connection device that transmits to the work relay device, and each of the duplexed two-branch connection devices monitors a failure of the duplexed network relay device and serves as a master. When a failure occurs in one of the network relay apparatuses, the other network relay apparatus that is a slave is switched to the master.

  According to the present invention, the duplexed two-branch connection device monitors a failure of the network relay device, and when a failure occurs in the network relay device, the master-slave relationship of the network relay device is quickly switched. For this reason, the relay of the frame by the network relay device as the master can be continued, and the availability in the transmission / reception of the frame using the duplexed network can be increased.

1 is a network connection diagram showing a configuration example of a duplex network system in an embodiment of the present invention. It is explanatory drawing which shows the outline | summary of each apparatus which comprises the duplex network system in one embodiment of this invention. It is a block diagram which shows the example of an internal structure of the network relay apparatus in one embodiment of this invention. FIG. 2 is a diagram illustrating an example of a transmission path of a frame configured between an active computer and a 1-system network and a 2-system network in a network relay device according to an embodiment of the present invention. It is a block diagram which shows the detailed structural example of the network switch and 2 branch connection apparatus in one embodiment of this invention. It is explanatory drawing which shows the example of the frame format in one embodiment of this invention. It is a block diagram which shows the example which the duplication computer of one embodiment of this invention monitors operation | movement of the network relay apparatus in a branch line using the monitoring program in a branch line. It is a flowchart which shows the example which the operation | movement of the network relay apparatus in a branch line monitors the operation | movement of the duplex computer of one embodiment of this invention using the monitoring program in a branch line. It is a block diagram which shows the example of a connection structure of the network relay apparatus in the 1st station of the example of 1 embodiment of this invention. It is a flowchart which shows the example of the stop process of a function when the 1st network relay apparatus of one embodiment of this invention detects a failure. It is a block diagram which shows the outline | summary of the network monitoring apparatus of one embodiment of this invention. It is a flowchart which shows the example of the network monitoring process of one embodiment of this invention. It is explanatory drawing which shows the example of the path | route which the network monitoring apparatus of one embodiment of this invention monitors between a duplex network connection apparatus and a duplex network relay apparatus. It is explanatory drawing which shows the example which monitors the network relay apparatus made into the standby system of the example of 1 embodiment of this invention.

  Hereinafter, an embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described with reference to the accompanying drawings. In this embodiment, an example will be described in which the present invention is applied to a duplex network system 7 in which the reliability of frame transmission processing performed using a duplex network is improved. The duplex network system 7 is also used as a failure monitoring system that realizes a failure monitoring method that is performed in cooperation with internal blocks (to be described later) by a computer executing a program.

FIG. 1 is a network connection diagram showing a configuration example of the duplex network system 7.
The duplex network system 7 includes a duplex network (hereinafter collectively referred to as “duplex network 5”), which is a 1-system network 5a and a 2-system network 5b. The duplex network 5 is, for example, a wide-band trunk transmission line provided by optical fibers, and can transfer frames at high speed.

  The duplex network system 7 includes a 1-system network relay device 2a determined as a master and a 2-system network relay device 2b determined as a slave (hereinafter collectively referred to as “duplex network relay device 2”). Prepare. In the following description, the network and the device determined as the master among the duplexed two-system network and the duplexed device actually process the frame as “active system”. On the other hand, it is assumed that the network and the device determined as slaves assist the active system as a “standby system” or perform frame processing instead when a failure occurs in the active system.

  Hereinafter, the configuration and operation of the active system will be described, but the standby system performs the same configuration and operation as the active system. The active system is the 1-system network relay device 1a, the 2-branch connection device 10a (see FIG. 2), and the 1-system computer 1a. The standby system is the 2-system network relay device 2b, the 2-branch connection device 10b ( This is a 2 system computer 1b (see FIG. 2).

  The duplex network relay device 2 is connected to a duplex computer device (hereinafter collectively referred to as “duplex computer 1”), which is a 1-system computer 1a and a 2-system computer 1b, respectively. Send and receive. Two-branch connection devices 10a and 10b are connected to the duplex computer 1 (see FIG. 2 described later), and the 1-system computer 1a and the 2-system computer 1b operate independently. The two-branch connection devices 10a and 10b branch paths through which the first-system computer 1a and second-system computer 1b transmit and receive, and operate independently.

  A 1-system network relay device 2a, which is a transmission source of a frame received from the 1-system computer 1a, relays a frame transmitted by the duplex computer 1 and is installed at another station connected to the network. Send to device 2a. On the other hand, the 1-system network relay device 2a installed at another station that is the destination of the frame sends the frame received from the 1-system network relay device 2a as the transmission source via the duplex network 5 to the duplex computer 1. Relaying. The frame is assigned a communication number for each frame relayed by the transmission source network relay device, together with a code for identifying the destination computer and the destination network relay device (for example, MAC address, IP address). Therefore, even if the destination network relay device receives two identical frames from the duplicated network, it can determine whether the frame has already been relayed based on the communication number attached to the frame.

  The duplex network 5 shown in FIG. 1 includes duplex network connection devices (hereinafter referred to as “duplex network connection device 3”), which are a 1-system network connection device 3a and a 2-system network connection device 3b, respectively. The dual network relay device 2 is installed via a generic name). The duplex network connection device 3 is connected to the duplex network 5, transmits the frame received from the duplex network relay device 2 to the duplex network 5, and receives the frame received from the duplex network 5 as 2. It transmits to the redundant network relay device 2. Further, since the duplex network relay device 2 is installed at each station, frame communication between the stations is performed via the duplex network 5. The 1-system network connection device 3a and the 2-system network connection device 3b operate independently of each other.

  Here, the 1-system network connection device 3a installed at the first station is connected to the 1-system network 5a, and the 2-system network connection device 3b is connected to the 2-system network 5b. Further, the 1-system computer 1a and the 2-system computer 1b are connected to the duplex network relay device 2 installed in the first station, respectively.

  The duplex network system 7 includes a network monitoring device 6 that monitors the operation of the duplex network relay device 2 installed at the first and second stations. The network monitoring device 6 is installed in a monitoring center that monitors the frame transmission / reception status of each device connected to the duplex network 5, and performs centralized monitoring control. Then, the network monitoring device 6 activates a network monitoring program to be described later, remotely monitors the operation of each device connected to the duplex network 5, and detects the failure of the duplex network relay device 2, and then master- We are reviewing slave relationships.

  The duplex computer 1 and the duplex network relay device 2 employ a so-called hot standby duplex system. The 1-system computer 1a operates as an active system that executes a predetermined application program, and the 1-system network relay device 2a relays the frame to the duplex network 5 as the active system. The 2 system computer 1b operates as a standby system waiting for execution of the application program, and the 2 system network relay device 2b operates as a standby system when the operation of the 1 system network relay device 2a becomes abnormal. The frame is relayed to the duplex network 5.

  The hot standby duplex computer 1 is used when the normal function of the active system 1 computer 1a is lost or when a communication failure occurs between the system 1a and the duplex network connection device 3. The following operations are performed. That is, in such a case, the active 1-system computer 1a becomes the standby system, and the standby 2-system computer 1b until then becomes the active system, and a predetermined application is continuously executed.

  In addition, although the 2nd computer, the 2nd network relay apparatus 2, and the 2nd network connection apparatus 3 are each installed also about a 2nd station, the overlapping description is abbreviate | omitted. Further, a branch line transmission line connecting the duplex network relay device 2 and the duplex network connection device 3 and a branch line transmission line connecting the duplex network relay device 2 and the duplex computer 1 are abbreviated as “branch line”. Sometimes said. The branch line can be increased or decreased according to the system configuration. Each device connected in the branch line is called a “network node”. In addition, for example, when a cable or the like is erroneously connected, a frame received by the duplex computer 1 or the duplex network relay device 2 is discarded.

Next, an outline of the configuration of the duplex network system 7 will be described.
FIG. 2 is an explanatory diagram showing an outline of each device constituting the duplex network system 7.
The duplex network relay device 2 installed at the first station is connected to the duplex network 5 via the duplex network connection device 3 as described above. The duplex network relay device 2 is duplexed by two sets of network switches 20a and 20b and two branch connection devices 10a and 10b, respectively. The duplex network relay device 2 relays the frame received from the two-branch connection device 10a and sends the frame to the duplex network relay device 2 installed at another station connected to the duplex network 5. Send. In addition, a frame received from another duplex network relay device 2 via the duplex network 5 is relayed to the two-branch connection devices 10a and 10b. Here, the two-branch connection devices 10a and 10b perform frame transmission / reception preferentially with respect to the 1-system network relay device 2a as a master.

  The duplexed network switch 20a is represented as network switches 20a-1 and 20a-2, and the duplexed two-branch connection device 10a is represented as two-branch connection devices 10a-1 and 10a-2. Similarly, the duplexed network switch 20b is represented as network switches 20b-1 and 20b-2, and the duplexed two-branch connection device 10b is represented as two-branch connection devices 10b-1 and 10b-2. . However, in the drawings after FIG. 3, for the sake of brevity, the network switches 20a and 20b are represented as the two-branch connection devices 10a and 10b.

  An active two-branch connection device 10a is connected to the first-system computer 1a, and a standby two-branch connection device 10b is connected to the second-system computer 1b. When the active system transmits a frame, the two-branch connection device 10a branches the frame received from the first-system computer 1a into a plurality of paths (for example, two paths) to the network switches 20a and 20b, and transmits them. The standby two-branch connection device 10b branches the frame received from the second-system computer 1b to a plurality of paths (for example, two paths) to the network switches 20a and 20b, respectively, and transmits them.

  The active 1-system network relay device 2a is connected to the 1-system network connection device 3a and the 2-system network connection device 3b. The standby system 2 network relay device 2b is connected to the system 1 network connection device 3a and system 2 network connection device 3b. However, the 1-system network relay device 2a and the 2-system network relay device 2b are configured to monitor each other's operation status.

  When receiving a frame in the active system, the 1-system network relay device 2a receives the frame from the active 1-system network 5a via the 1-system network connection device 3a. The received frame is sent to the two-branch connection device 10a via the network switch 20a. The two-branch connection device 10a transmits a frame received from a plurality of paths (for example, two paths) to the 1-system computer 1a, and the 1-system computer 1a receives the frame.

Here, an overview of the following first to fourth monitoring processes will be described for the monitoring process for detecting a failure according to the present embodiment. Details of these monitoring processes will be described later.
(1) First monitoring processing The first-system network relay device 2a and the second-system network relay device 2b perform fault monitoring of each part in the own device. Note that failure monitoring (timer check, parity check, etc.) of the own device is a process that has been performed conventionally, and thus detailed description thereof is omitted.
(2) Second monitoring processing The duplex computer 1 equipped with the branch line monitoring program monitors the failure between the 1-system network relay device 2a, 2-system network relay device 2b and the 2-branch connection devices 10a, 10b. I do. When a failure occurs in the master (active system) 1-system network relay device 2a, the slave (standby system) 2-system network relay device 2b is switched to the master.

(3) Third monitoring processing The 1-system network relay device 2a and the 2-system network relay device 2b perform fault monitoring on each other. Here, when the 1-system network relay device 2a and the 2-system network relay device 2b send the monitoring frame to each other and cannot receive the response frame from the other system, it is determined that the other-system network relay device is stopped.
(4) Fourth monitoring processing The network monitoring device 6 performs fault monitoring of the duplex network relay device 2 at the first or second station via the duplex network 5, and duplexes when a failure occurs. Controls switching of the master and slave of the network relay device 2. At this time, the network monitoring device 6 sends a path diagnosis command (hereinafter referred to as a “ping command”) to the duplex computer 1 installed at the first station, and confirms that the duplex computer 1 is operating. Monitoring. In addition, the network monitoring device 6 monitors the operation of the duplex network connection device 3 and periodically collects logs of the duplex network relay device 2 to check for failures occurring in the duplex network relay device 2. Detect signs.

Next, a detailed configuration example of the duplex network relay device 2 will be described.
FIG. 3 is a block diagram showing an example of the internal configuration of the duplex network relay device 2. 3 to 5, the configurations and operations of the two-branch connection devices 10a and 10b and the network switches 20a and 20b shown in FIG. 2 are simplified and described.

  The duplex network 5 is configured as a ring network, and the 1-system network 5a and the 2-system network 5b operate independently of each other. Therefore, the frame transmitted from the duplex computer 1 installed at the first station is separated into two identical frames by the duplex network relay device 2. The separated frames are separately transmitted via the duplex network 5 to, for example, the duplex computer 1 serving as a destination installed at the second station. However, the duplex computer 1 actually installed at the second station receives only the frame that arrives first, and the frame that arrives later is discarded by the duplex network relay device 2 of the destination. .

  The network switch 20 provided in the duplex network relay device 2 can be configured using, for example, a general switching hub. The basic function is to take out a frame addressed to the duplex computer 1 connected to the duplex network relay device 2 from the frame communicated in the duplex network 5 and transfer the fetched frame to the duplex computer 1. There is to send.

  The network switch 20 is a transmission path that a general switching hub does not have, such as a function of returning a predetermined response frame in response to a monitoring frame transmitted from the 1-system network 5a installed at another station. It also has a function of diagnosing.

  The two-branch connection device 10 has a function of branching one transmission path into two transmission paths and merging the two transmission paths into one transmission path. That is, the two-branch connection device 10 branches the transmission path connected to the duplex computer 1 into a transmission path that reaches the 1-system network 5a and a transmission path that reaches the 2-system network 5b. Further, the transmission path from the 1-system network 5 a and the transmission path from the 2-system network 5 b are merged with the transmission path connected to the duplex computer 1.

  FIG. 4 is a diagram illustrating an example of a transmission path of a frame configured between the active computer and the duplex network 5 in the duplex network relay device 2. FIG. 4A shows an operating transmission line when the 1-system computer 1a is the active system, and FIG. 4B shows an operating transmission line when the 2-system computer 1b is the active system. In FIG. 4, a thick solid line represents an active transmission path, and a broken line represents a standby transmission path.

  As shown in FIG. 4A, when the 1-system computer 1a is the active system, the 1-system computer 1a is connected via the 2-branch connection device 10a, the network switch 20a, and the 1-system network connection device 3a by the transmission line in operation. It is connected to the system 1 network 5a. Furthermore, the 1-system computer 1a is connected to the 2-system network 5b via the 2-branch connection device 10a, the network switch 20b, and the 2-system network connection device 3b.

  Further, as shown in FIG. 4B, when the second system computer 1b is the active system, the second system computer 1b connects the two branch connection device 10b, the network switch 20a, and the first system network connection device 3a with the transmission line in operation. To the 1-system network 5a. Further, the 2-system computer 1b is connected to the 2-system network 5b via the 2-branch connection device 10b, the network switch 20b, and the 2-system network connection device 3b.

  As described above, the basic functions of the network switch 20 and the two-branch connection device 10 are to switch the transmission path between the duplex computer 1 and the duplex network connection device 3.

Next, a more detailed configuration and function of the duplex network relay device 2 will be described with reference to FIG.
FIG. 5 is a block diagram illustrating a detailed configuration example of the network switch 20 and the two-branch connection device 10.

  As described above, in the two-branch connection device 10, the transmission path 11 connected to the duplex computer 1 is divided into the transmission path 12 leading to the 1-system network 5a and the transmission path 13 reaching the 2-system network 5b. Branch off.

  In general, a transmission path is configured by a pair of a transmission transmission path and a reception transmission path, but frame transmission / reception processing in the two-branch connection device 10 is partially different between the transmission transmission path and the reception transmission path. Since it is, it supplements below.

  In the two-branch connection device 10, for the transmission transmission line on the side where the frame is transmitted from the duplex computer 1, the transmission line 11 is simply branched into the transmission line 12 and the transmission line 13. I just need it. Then, the same frame is output to the transmission path 12 on the 1-system network 5a side and the transmission path 13 on the 2-system network 5b side by the 2-branch connection device 10 from the frame output from the active 1-system computer 1a. Will be sent out. It should be noted that a frame that reaches the 1-system network 5a or the 2-system network 5b is not sent from the standby-system 2 computer 1b.

  On the other hand, for the transmission path on the side where the duplex computer 1 receives a frame, the transmission paths 11 to 13 are separated as a hardware configuration. This is intended to avoid a collision between a frame from the transmission path 12 and a frame from the transmission path 13. Accordingly, the two-branch connection device 10 is provided with a reception frame transmission control unit 14 that performs transmission control for adjusting the collision of frames.

  That is, the reception frame transmission control unit 14 is provided with, for example, a buffer memory 15 that temporarily stores reception frames. The received frame from the 1-system network 5 a and the received frame from the 2 system network 5 b are temporarily stored in the buffer memory 15, and then sequentially transmitted to the transmission path 11 connected to the duplex computer 1.

Next, a detailed configuration and function of the network switch 20 will be described.
The network switch 20 includes a frame transmission control unit 21, a path switching unit 22, a monitoring frame transmission control unit 23, an active connection switch control unit 24, a duplicate frame discard processing unit 25, a reception management table 26, a transmission management table 27, and a buffer memory. 28.

  The frame transmission control unit 21 has a configuration and a function corresponding to a so-called general switching hub itself, and constitutes a part of a trunk transmission line of the 1-system network 5a or the 2-system network 5b.

  That is, the frame transmission control unit 21 is provided with a plurality of communication ports (not shown). Each communication port has a connection terminal for an input transmission path and an output transmission path. The frame transmission control unit 21 appropriately determines a communication port that outputs the frame according to a destination address (MAC address or the like) included in the frame input from the input transmission path of a certain communication port. Then, the frame transmission control unit 21 sends the input frame to the output transmission path connected to the determined communication port. At this time, the frame transmission control unit 21 transmits the frame with a communication number indicating the transmission order of the frames.

  On the other hand, when a frame arrives from the duplex network 5 by a one-to-many communication method (for example, broadcast), the frame transmission control unit 21 sets the communication number acquired from the frame for each duplex network relay device 2 of the transmission source. To the reception management table 26. When a frame arrives from the duplex network 5 in a one-to-one communication method (for example, unicast), a duplex network relay device that transmits the communication number acquired from the frame and the identification code for identifying the computer 2 is written in the reception management table 26 to manage the arrival order of frames for each communication method.

  In this manner, the communication number of the frame received by the destination duplex network relay device 2 from the duplex network 5 is managed for each communication method. For this reason, the duplex network relay device 2 of the transmission source manages the transmission communication number of the frame transmitted by broadcast. On the other hand, the destination duplex network relay device 2 manages the reception communication number of the frame received by unicast and the MAC address of the duplex computer 1, and identifies the duplex computer 1 that relays the frame. Yes. For this reason, even when a frame in which unicast and broadcast are mixed arrives, the destination duplex network relay device 2 can identify that the frame has been received correctly.

  The path switching unit 22 changes the transmission path to be connected to the transmission path 21a connected to the frame transmission control unit 21 from the transmission path 22a to the first computer 1a and the transmission path 22b to the second computer 1b. This is a device that selects and switches the connection relationship. A switch SWa is installed on the transmission path 22a, and a switch SWb is installed on the transmission path 22b, one of which is turned on and the other is turned off. In FIG. 5, the switch SWa is on and the switch SWb is off.

  The on / off control of the switches SWa and SWb is performed by an active system instruction signal supplied from the active system connection switch control unit 24. Here, the working system instruction signal is a signal that instructs either the 1-system computer 1a or the 2-system computer 1b as the working system. As for the switches SWa and SWb, the switches on the transmission lines 22a and 22b connected to the 1-system computer 1a or the 2-system computer 1b which are the active systems are turned on, and the other is turned off.

  Accordingly, the network switches 20a and 20b connect a transmission path to the first-system computer 1a or the second-system computer 1b that is the active system. Then, the transmission path to the second system computer 1b or the first system computer 1a serving as the standby system is disconnected.

  Note that these switches SWa and SWb are not limited to those that cut the transmission line in hardware. For example, when a microprocessor is installed in the network switch 20, the switch SWa depends on whether the microprocessor transmits / receives a frame to / from the duplex computer 1 under program control or stops transmission / reception. , SWb may be turned on or off.

  When the monitoring frame transmission control unit 23 receives the monitoring frame transmitted from the duplex computer 1 to the own device (network switch 20), if the own device is operating normally at that time, A response frame including information indicating normality is returned to each of the duplex computers 1 of the transmission source.

  Here, the monitoring frame transmitted from the duplex computer 1 includes information indicating its own operation state, that is, information indicating whether it is an active system or a standby system. The active connection switch control unit 24 extracts information indicating whether it is the active system or the standby system from the monitoring frame received by the monitoring frame transmission control unit 23, and sends the information to the path switching unit 22 based on the information. On the other hand, an active system instruction signal is output. The active system instruction signal is, for example, a 1-bit flag signal. When it is “0”, the 1-system computer 1a is determined as the active system, and when it is “1”, the 2-system computer 1b is determined as the standby system.

  As described above, the duplex network 5 transmits frames independently of each other. Here, the frame transmitted from the active 1-system computer 1a is delivered to the active 1-system computer 1a as the destination via both the 1-system network 5a and the 2-system network 5b. In this case, the destination active system 1 computer 1a has received the same frame twice, and it is necessary to discard one of the frames.

  Duplicate frame discard processing can be performed by the active 1-system computer 1a itself. Therefore, a duplicate frame discard processing unit 25 is provided in each of the network switches 20a and 20b included in the duplex network relay device 2, and one of the duplicate frames is discarded by the duplicate frame discard processing unit 25. The duplicate frame discard processing unit 25 arrives first from the network among the frames delivered from the frame transmission control unit 21 when the source duplex network relay device 2 transmits the same frame in the duplex network 5. The frame is received and returned to the frame transmission control unit 21. Then, the same communication number as that of the first-arrived frame is attached, and the later-arrived frame from the network is subjected to a discarding process.

  Specifically, the duplicate frame discard processing unit 25 of the network switch 20a extracts a frame addressed to the active system 1 computer 1a from the frame received by the frame transmission control unit 21. Then, the duplicated frame discard processing unit 25 of the other network switch 20b in the same duplex network relay device 2 compares with the frame extracted in the same manner. In this comparison, a communication number attached to the frame is referred to as described later.

  For example, if the same frame as the received frame has already been taken out by the duplicate frame discard processing unit 25 of the other network switch 20b, that is, if there is a first-arrival frame, the later-arrived frame is discarded. To do. As a result, the active system 1 computer 1a does not need to receive duplicate frames.

  The above processing is similarly performed when the 1-system computer 1a is a standby system and the 2-system computer 1b is an active system. At this time, the processing blocks described as the active system and the standby system in the above process may be reversed.

  The communication numbers attached to the frames are managed using the reception management table 26 in the order in which the frames arrived at the duplex network relay device 2. The duplex network relay device 2 creates a reception management table 26 for every duplex network relay device 2 connected to the duplex network 5 via the duplex network connection device 3. This reception management table 26 manages the arrival order of frames arriving from the duplex network 5, and also indicates a communication number indicating the order in which frames are transmitted by the duplex network relay device 2 of the transmission source. Management is performed for each duplex network relay device 2. The reception management table 26 is provided for each of the network switches 20 a and 20 b, and there are a plurality of reception management tables 26 for each duplex network relay device 2 of each station connected to the duplex network 5. Therefore, the communication number of the frame can be individually managed for the duplex network relay device 2 that is the transmission source of the frame received from the duplex network 5.

  When the network switch 20a is set to the active system, the frame transmission control unit 21 appropriately synchronizes the content written in the active system reception management table 26 with the standby system reception management table 26. As a result, even when the network switch 20a is changed to the standby system and the network switch 20b is changed to the active system, the network switch 20b takes over management of the reception status of the frame by the reception management table 26 held by itself. be able to.

  Further, the communication numbers attached to the frames transmitted by the duplex computer 1 are managed using the transmission management table 27 in the order in which the duplex network relay device 2 transmits. The transmission management table 27 is provided for each of the network switches 20a and 20b, and there are a plurality of transmission management tables 27 for each duplex network relay device 2 of each station connected to the duplex network 5.

  When the network switch 20a is set to the active system, the frame transmission control unit 21 appropriately synchronizes the contents written in the active system transmission management table 27 with the standby system transmission management table 27. As a result, even when the network switch 20a is changed to the standby system and the network switch 20b is changed to the active system, the network switch 20b takes over management of the reception status of the frame by the transmission management table 27 held by itself. be able to.

Next, a configuration example of the frame will be described.
FIG. 6 is an explanatory diagram showing an example of a frame format. 6A shows an example of a frame format of a frame relayed by the duplex network relay device 2, and FIG. 6B is an explanatory diagram showing an example of a frame format of a frame communicated between the duplex network relay devices 2. .

  The frame format shown in FIG. 6A is applied to a frame relayed by the duplex network relay device 2. This frame format includes a MAC address field, an IP address field, a user information field, and a transmission / reception number field. Note that information other than these fields may be included, but description thereof is omitted here.

In the MAC address field, a MAC address for specifying a destination computer when unicast communication is performed is written.
An IP address assigned to the network relay device is written in the IP address field.
In the user information field, it is written which communication method the unicast communication or broadcast communication transmitted. This communication method information is given as an example of user information, and includes various other information.
In the transmission communication number field, the communication number of the frame to be transmitted is written.
In the reception communication number field, the communication number of the received frame is written.
The number of transmission / reception number fields can be increased or decreased according to the number of communication methods used in the duplex network system 7, and is also referred to as “trailer”.

  When transmitting and receiving a frame using broadcast, for example, Internet Control Message Protocol (ICMP) and User Datagram Protocol (UDP) are used. Further, when transmitting and receiving frames using unicast, for example, ICMP, UDP, and TCP (Transmission Control Protocol) are used.

  When the duplex network relay device 2 receives a frame from the duplex computer 1 in the branch line, it adds a transmission / reception communication number field and relays the frame to the duplex network 5 via the duplex network connection device 3. To do. Processing for adding a transmission / reception communication number field to a frame in this way is called “encapsulation processing”. On the contrary, the duplex network relay device 2 reads the content of the transmission / reception communication number field from the frame received from the duplex network 5 via the duplex network connection device 3, and then transmits the transmission / reception communication number field. Excluding the frame, the frame is relayed to the duplex computer 1 in the branch line. Processing for removing the transmission / reception communication number field from the frame in this way is called “decapsulation processing”.

  Here, it is desirable to add the transmission / reception communication number field to the end of the frame. For example, when a network failure occurs during frame transmission, an analyzer is inserted in the middle of the duplex network 5 to analyze the contents of the frame and the communication status of the duplex network 5. This analyzer generally confirms the contents extracted from the frame in the order of the MAC address field, IP address field, and user information field, and analyzes the protocol. For this reason, it is necessary to examine the location where the transmission / reception communication number field is arranged so that the analysis by the analyzer is easy. In the frame according to the present embodiment, by providing a transmission / reception communication number field after the user information field, the analysis range of the analyzer is not affected without affecting the analysis and the journal function performed by a conventional analyzer. Can be followed in a general field sequence.

  The frame format shown in FIG. 6B is applied to a frame used when communicating between the 1-system network relay device 2a and the 2-system network relay device 2b. This frame format includes a destination address field, a source address field, a type / data length field (MAC header up to here), a communication number field, a network relay device information field, a padding field, and a communication number inversion field (data section up to here) , A CRC (Cyclic Redundancy Check) field is included.

The destination address field contains the address of the destination network relay device. For example, a multicast address is used as this address, and is discarded when a device other than the destination network relay device receives the frame.
The transmission source address field includes information indicating the distinction between the 1st system and the 2nd system. As a result, the destination network relay device can determine from which system the frame has been received.
The type / data length field includes the data length of the data portion together with a value indicating the type of frame.

The communication number field includes the frame communication number as described above. As a result, the destination network relay device can determine first-frame reception of the frame.
The network relay device information field includes various monitoring commands, responses, and the like performed on the destination network relay device.
A predetermined value is filled in the padding field in order to make the data length uniform.
The communication number inversion field includes a pattern in which the communication number of the frame included in the communication number field is inverted. A consistency check with the communication number is performed based on the inverted pattern.
The CRC field includes an error detection code used as a frame checksum.

[Example of second monitoring process]
Next, communication monitoring processing in the duplex network system 7 will be described with reference to FIGS.
FIG. 7 is a block diagram illustrating an example in which the duplex computer 1 monitors the operation of the duplex network relay device 2 in the branch line using the branch line monitoring program.
The in-branch monitoring program is used in the second monitoring process described above to control the two-branch connection devices 10a and 10b and monitor the paths of the respective devices in the branch line. Both the 1-system computer 1a and the 2-system computer 1b execute the branch line monitoring program.

  The 1-system computer 1a is connected to the 2-branch connection device 10a-1, the 1-system network relay device 2a, and the 2-system network relay device 2b via the 1-system LAN. The 1-system computer 1a is connected to the 2-branch connection device 10a-2, the 1-system network relay device 2a, and the 2-system network relay device 2b via the 2-system LAN. Similarly, the 2-system computer 1b is connected to the 2-branch connection device 10b-1, the 1-system network relay device 2a, and the 2-system network relay device 2b via the 1-system LAN. The 2 system computer 1b is connected to the 2 branch connection device 10b-2, the 1 system network relay device 2a and the 2 system network relay device 2b via the 2 system LAN. The two-branch connection devices 10a and 10b monitor the failure of the duplex network relay device 2 respectively, and when a failure occurs in the 1-system network relay device 2a serving as a master, the 2-system connected as a slave Control is performed to switch the network relay device 2b to the master.

  Here, the route search between the duplex computer 1 and the duplex network relay device 2 and the configuration management of the duplex network relay device 2 can be performed by a network monitoring program to be described later. However, since the wiring of the LAN cable or the like is shorter in the branch line than through the trunk line, the monitoring command can be transmitted and received earlier in the branch line and the failure can be detected earlier. Moreover, if the branch line monitoring program is used, monitoring for the purpose of managing the master-slave of the duplex network relay device 2 can be performed. The path diagnosis between the duplex network relay device 2 and the duplex network connection device 3 is performed by a network monitoring program described later.

  FIG. 8 is a flowchart showing an example in which the duplex computer 1 monitors the operation of the duplex network relay device 2 in the branch line using the branch line monitoring program.

  First, the 2-branch connection device 10a monitors the operations of the 1-system LAN and the 2-system LAN, the active-system 1-system network relay device 2a, and the standby-system 2-system network relay device 2b according to instructions from the system 1 computer 1a. In response to an instruction from the 2-system computer 1b, the 2-branch connection device 10b monitors the operations of the 1-system LAN and 2-system LAN, the active-system 1-system network relay device 2a, and the standby-system 2-system network relay device 2b. Through these monitoring, the two-branch connection devices 10a and 10b determine the operating state of the duplex network relay device 2 in the branch line, and determine which of the 1-system LAN and the 2-system LAN is operating as the active system. (Step S1).

  Here, the two branch connection devices 10a and 10b send the monitoring frame received from the duplex computer 1 to the duplex network relay device 2, and the response message from the duplex network relay device 2 is several seconds (for example, 2 seconds). ) If it is not received even after a while, a monitoring frame is sent again. For example, if a response message cannot be received from the duplex network relay device 2 even if the monitoring frame is retransmitted up to three times, it is determined that a communication error has occurred.

Next, in response to an instruction from the duplex computer 1, the two-branch connection devices 10a and 10b determine a communication path between the active system 1 network relay device 2a and the duplex computer 1. In addition, the operating state of the active 1-system network relay device 2a is determined . Further, it is determined which of the 1-system network relay device 2a and the 2-system network relay device 2b is operating as the active system (step S2).

  Next, the duplex computer 1 makes the following determination. That is, when the duplex computer 1 determines that all of the 1-system network relay device 2a and the 2-system network relay device 2b are in communication abnormality, the 2-branch connection devices 10a and 10b output an error message (step S3). .

  When the duplex computer 1 determines that there is an abnormality in the path of the active 1-system network relay device 2a and the standby system 2-system network relay device 2b has a normal path, the duplex computer 1 It is determined that a certain 2-system network relay device 2b is operating. At this time, the two-branch connection devices 10a and 10b instruct the standby second-system network relay device 2b to switch the second-system network relay device 2b that was a slave to the master, and the second-system network relay device 2b The system is switched from the slave to the master (step S4).

The duplex computer 1 determines that the standby system 2 network relay device 2b is in a stopped state when an abnormality occurs in the path of the standby system 2 network relay device 2b. At this time, the duplex computer 1 instructs the active system 1 network relay apparatus 2a to stop the standby system 2 network relay apparatus 2b. As a result, the operation of the standby system 2 network relay device 2b is stopped (step S5).
Note that the processes up to steps S1 and S32 and the determination processes of S33 to S35 are repeated, for example, every second. Thereby, it is possible to always monitor the operating state of each device.

[Example of third monitoring process]
Next, an example in which the first-system network relay device 2a and the second-system network relay device 2b perform fault monitoring in the third monitoring process described above will be described with reference to FIGS.
FIG. 9 is a block diagram illustrating a connection configuration example of the 1-system network relay device 2a and the 2-system network relay device 2b in the first station.

  The 1-system network relay device 2a and the 2-system network relay device 2b are connected to each other by a redundant inter-relay device LAN 4a and a single control line 4b. The inter-relay device LAN 4a is constructed by, for example, 100BASE-TX, and monitoring frames for monitoring the operation state of the first-system network relay device 2a and the second-system network relay device 2b are transmitted and received. Therefore, the system 1 network relay device 2a monitors the failure of the system 2 network relay device 2b, and the system 2 network relay device 2b monitors the failure of the system 1 network relay device 2a. Here, when a failure occurs in the 1-system network relay device 2a as the master, the 2-system network relay device 2b as the slave is switched to the master and the processing is continued. In the following description, the 1-system network relay device 2a that is the subject of the monitoring operation is referred to as “own system”, and the 2-system network relay device 2b that is the monitoring target is referred to as “other system”. The system is a relative concept.

  As described above, the duplexed 1-system network relay device 2a and 2-system network relay device 2b perform operation monitoring by monitoring frame transmission / reception using the inter-relay device LAN 4a and status monitoring of the control line 4b. The monitoring using the inter-relay device LAN 4a and the control line 4b is performed, for example, about every 200 milliseconds. In monitoring using the inter-relay device LAN 4a, for example, even if 1 second (200 milliseconds × 5 times) elapses, the own system does not receive a monitoring frame from the other system in both the inter-relay device LAN 4a. It is determined that the other system is stopped.

  In the state monitoring using the control line 4b, the own system is connected to the own system, the control line 4b is connected to the other system, the other system is connected to the control line 4b, and the other system is in the power state (powered on). Monitoring). Then, the own system determines whether the own system is the first system or the second system when the own system power is turned on. Here, when both the own system and another system are operating, the first system is determined as the master. However, if the power of system 1 is turned off, the other system that is system 2 is determined as the master.

Here, an example of operation of the own system performed in the state monitoring using the control line 4b and determination conditions will be described.
(1) When the control line 4b is not connected to the own system, the own system turns on a warning lamp (not shown) and stops the operation of the own system.
(2) When the control line 4b is connected to the own system but the control line 4b is not connected to the other system, the link of the inter-relay device LAN 4a is confirmed and the monitoring frame transmitted from the other system is received. wait. If the monitoring frame cannot be received from another system, the local system is determined as the master.
(3) The determination as to whether or not the power supply of the other system is off is made by checking that the state of the control line 4b is “There is other system connection” and the state of the other system found from the control line 4b is “Power off”; The link between both of the LANs 4a between the relay apparatuses is disconnected.
(4) When the own system detects an abnormality in the other system, it is determined whether or not to stop the other system.

Then, when switching the master-slave relationship from the own system to another system, the following control items are required. Here, description will be made assuming that the own system is determined as the master.
(1) Stopping the switching function in the master When the local network switch 20a determined as the master and the other network switch 20b determined as the slave operate together as switching hubs, the 1-system computers 1a in the branch line are the same. Frame is received twice. Therefore, when the own system detects a failure of the network switch 20a, the own system stops the network switch 20a and switches the system to the network switch 20b of the other system.
(2) Stop of functions that affect other devices When an abnormality occurs in the second system network connection device 3b, the second system network relay device 2b is placed in another station if the second network connection device 3b continues to operate. This affects the duplex network relay device 2 that has been made. For this reason, the own system stops the operation in which the other system connects to the second system network connection apparatus 3b.

Next, an example of processing at the time of failure of the own system will be described.
FIG. 10 is a flowchart illustrating an example of a function stop process when the first-system network relay device 2a detects a failure. Here, the 1-system network relay device 2a is a master and the 2-system network relay device 2b is a slave.

  First, when the 1-system network relay device 2a detects its own hardware failure (step S11), the network switch 20a of the 1-system network relay device 2a is stopped (step S12), and reset such as hardware initialization is performed. It performs (step S13). Then, after the stop factor (contents of failure), trace data, and the like are stored in a memory (not shown), the function of the 1-system network relay device 2a itself is stopped (step S14).

  In step S13, the second-system network relay device 2b stops receiving the monitoring frame that the first-system network relay device 2a is supposed to transmit because the first-system network relay device 2a stops the network switch 20a. Is detected (step S15). At this time, the second-system network relay device 2b checks whether the power of the first-system network relay device 2a is turned on (step S16), and tests the second-system network relay device 2b itself using the inter-relay device LAN 4a. To confirm that the second-system network relay device 2b is operating normally (step S17).

  Thereafter, the second-system network relay device 2b outputs a reset signal to the first-system network relay device 2a (step S18). This reset signal is used to switch the second-system network relay device 2b set as the slave to the master.

  Here, when the 1-system network relay device 2a receives a reset signal from the 2nd-system network relay device 2b, the 1-system network relay device stores the stop factor (contents of the failure), trace data, and the like in a memory (not shown), The function of 2a itself is stopped (step S19). Thereafter, the main power supply is turned off by the user in order to replace the 1-system network relay device 2a (step S20).

  On the other hand, when the second-system network relay device 2b has been determined as the master from before, the second-system network relay device 2b operates as a single master as it is. On the other hand, if the second-system network relay device 2b has been determined as a slave before, the second-system network relay device 2b shifts to operate as a single master (step S21). Then, after confirming that the power of the 1-system network relay device 2a is turned off in step S20, the reset signal output to the 1-system 1-system network relay device 2a is turned off (step S22).

[Example of fourth monitoring process]
Next, an operation example of the network monitoring device 6 will be described with reference to FIGS. First, an example in which the network monitoring device 6 performs failure monitoring in the above-described fourth monitoring process will be described.
FIG. 11 is a block diagram showing an outline of the network monitoring device 6.

  The network monitoring device 6 is connected to the duplex network 5 and monitors the failure of the duplex network relay device 2 via the duplex network 5 and the duplex network connection device 3. When a failure occurs in the 1-system network relay device 2a that is the master, control is performed to switch the 2-system network relay device 2b that is the slave to the master.

  In the network monitoring device 6, a network monitoring program is operating and sends a monitoring frame to the duplex network connection device 3 installed at the first station (arrow indicated by (1) in the figure). Then, when there is no failure in the duplex network connection device 3, the network monitoring device 6 further sends a monitoring frame to the duplex network relay device 2 (arrow indicated by (2) in the figure). . At this time, if a failure occurs in the active system 1 network relay device 2a, the network monitoring device 6 performs processing such as switching the standby system 2 network relay device 2b from the slave to the master. The network monitoring device 6 sends a ping command to the duplex computer 1 (arrow indicated by (3) in the figure). Thereby, the route to the duplex computer 1 can be diagnosed.

  FIG. 12 is a flowchart illustrating an example of network monitoring processing performed by the network monitoring device 6. This process is performed for the duplex network relay device 2 and the duplex network connection device 3 of all stations connected to the duplex network 5.

  First, the network monitoring device 6 monitors the operations of the first-system network connection device 3a and the second-system network connection device 3b installed at the first station (step S31), and outputs an alarm when an abnormality is detected (step S31). S32).

  Next, the network monitoring device 6 monitors the operations of the 1-system network relay device 2a and the 2-system network relay device 2b installed at the first station (step S33), and the active 1-system network relay device 2a. Is switched to the standby system, and it is determined whether it is necessary to switch the master-slave relationship to switch the standby system 2 network relay device 2b to the active system (step S34). If it is not necessary to switch the master-slave relationship, it is determined whether or not the standby system 2 network relay device 2b needs to be stopped (step S35).

  If it is not necessary to stop the standby 2 system network relay device 2b, the network monitoring device 6 issues a ping command to the 1 system computer 1a and the 2 system computer 1b installed at the first station to double The route to the computer 1 is diagnosed (step S36). Upon receiving the path diagnosis result, the network monitoring device 6 determines again whether or not it is necessary to switch the master-slave relationship of the duplex network relay device 2 (step S37). In this case, if the path to the duplex computer 1 that should be connected to the active 1-system network relay device 2a is disconnected, it is necessary to switch the slave 2-system network relay device 2b to the master for operation. Because. If it is not necessary to switch the master-slave relationship, the process is terminated while maintaining the system.

  If it is determined in steps S34 and S27 that the master-slave relationship of the duplex network relay device 2 needs to be switched, the network monitoring device 6 gives an instruction to switch the slave 2-system network relay device 2b to the master. The second-system network relay device 2b is switched to the master (step S38). On the other hand, if it is determined in step S35 that the standby system 2 network relay device 2b need not be stopped, the network monitoring device 6 instructs the active system 1 network relay device 2a to Processing for stopping the second-system network relay device 2b is performed (step S39).

FIG. 13 is an explanatory diagram illustrating an example of a route monitored by the network monitoring device 6 between the duplex network connection device 3 and the duplex network relay device 2.
As described above, the network monitoring device 6 operates the network monitoring program to monitor the operation of the duplex network relay device 2 at each station connected to the duplex network 5. Here, it is assumed that the network monitoring device 6 sends a monitoring frame to the system 1 network connection device 3a via the system 1 network 5a. This monitoring frame is branched into two at the 1-system network connection device 3a and sent to the 1-system network relay device 2a and the 2-system network relay device 2b, respectively (arrows indicated by (1) and (2) in the figure). .

  The network monitoring device 6 sends a monitoring frame to the second system network connection device 3b via the second system network 5b. This monitoring frame is branched into two in the system 2 network connection device 3b and sent to the system 1 network relay device 2a and system 2 network relay device 2b, respectively (arrows indicated by (3) and (4) in the figure). .

  In this way, the network monitoring device 6 sends the monitoring frame to the duplex network relay device 2 at another station via the duplex network 5, and the duplex network connection device 3 and the duplex network relay. It is possible to monitor all paths of the device 2.

[Modification]
Note that it is also possible to monitor the standby system 2 network relay apparatus 2b installed in another station, regardless of the network monitoring apparatus 6 installed in the monitoring center.
FIG. 14 shows an example of a path for monitoring the operation of the standby system 2 network relay device 2 b connected to the system 1 computer 1 a via the duplex network 5.

  The second-system computer 1b that executes the network monitoring program can monitor the operation of the standby second-system network relay device 2b installed at another station via the duplex network 5. Here, the second-system computer 1b installed at the second station sends a monitoring frame to the first-system network 5a via the two-branch connection device 10a. At this time, the monitoring frame reaches the second-system network relay device 2b installed at the first station via the first-system network connection device 3a installed at the first station, and performs route diagnosis ((1) in the figure). Arrow).

  Further, the second-system computer 1b installed at the second station sends a monitoring frame to the second-system network 5b via the two-branch connection device 10b. At this time, the monitoring frame arrives at the second-system network relay device 2b installed at the first station via the second-system network connection device 3b installed at the first station, and performs route diagnosis ((2) in the figure). Arrow).

  The slave second system computer 1b monitors the network in this way because the standby system of the duplex network relay device 2 and the duplex network connection device 3 that cannot be monitored by the network monitoring program of the first system computer 1a. This is for monitoring the route to and from.

  According to the duplex network system 7 according to the embodiment described above, the duplex network connection device 3 causes a failure of the duplexed 1-system network relay device 2a and 2-system network relay device 2b. To monitor. Then, when a failure occurs in the 1-system network relay device 2a as the master, the duplex network connection device 3 gives an instruction to switch the 2-system network relay device 2b as the slave to the master, The processing can be quickly taken over from the 1-system 1-system network relay device 2a to the 2-system network relay device 2b.

  The duplexed 1-system network relay device 2a and 2-system network relay device 2b monitor each other for faults via the inter-relay device LAN 4a and the control line 4b. Also in this case, when a failure occurs in the 1-system network relay device 2a as the master, the 2-system network relay device 2b as the slave can switch itself to the master.

  Further, the network monitoring device 6 monitors the occurrence of a failure in the duplexed 1-system network relay device 2a and 2-system network relay device 2b via the duplex network 5 and the duplex network connection device 3. When a failure occurs in the 1-system network relay device 2a that is the master, the network monitoring device 6 instructs the 2-system network relay device 2b that is the slave to switch itself to the master.

  Then, by combining the monitoring by the duplex network connection device 3 and the monitoring between the duplexed 1-system network relay device 2a and the 2-system network relay device 2b and the monitoring by the network monitoring device 6, 2 It is possible to reliably detect a cable failure such as the redundant network relay device 2 and the LAN and respond quickly. For this reason, the availability in the duplex network system 7 can be increased.

  Also, the duplex network relay device 2 creates a reception management table 26 for every duplex network relay device 2 connected to the duplex network 5 via the duplex network connection device 3. . Therefore, the communication number of the frame can be individually managed for the duplex network relay device 2 that is the transmission source of the frame received from the duplex network 5.

  The above-described duplex network system 7 is not only used for frame communication between stations, but also when a remote server transmits a frame to a client, or when computers with different processing speeds perform processing together. Is also effective.

  Moreover, although the example applied to broadcast was demonstrated as an example of a one-to-many communication system, you may apply to a multicast and anycast. The network topology of the duplex network 5 is configured as a ring type, but various connection forms such as a mesh type, a duplexed bus network, and a duplexed star type may be employed. it can.

  Further, the encapsulation process and the decapsulation process can be applied not only to the duplex network system 7 but also to various network systems such as a VLAN (Virtual Local Area Network).

  The series of processes in the above-described embodiment can be executed by hardware, but can also be executed by software. When a series of processing is executed by software, it can be executed by a computer in which a program constituting the software is incorporated in dedicated hardware or a computer in which programs for executing various functions are installed. . For example, a program constituting desired software may be installed and executed on a general-purpose personal computer or the like.

  Further, a recording medium that records a program code of software that realizes the functions of the above-described embodiments may be supplied to the system or apparatus. It goes without saying that the same function as that of the present embodiment can also be realized by reading and executing a program code stored in a recording medium by a computer (or a control device such as a CPU) of the system or apparatus. .

  As a recording medium for supplying the program code in this case, for example, a flexible disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, etc. are used. Can do.

  Further, the functions of the above-described embodiment are realized by executing the program code read by the computer. In addition, an OS or the like running on the computer performs part or all of the actual processing based on the instruction of the program code. The case where the function of the above-described embodiment is realized by the processing is also included.

  Further, the present invention is not limited to the above-described embodiments, and various other application examples and modifications can be taken without departing from the gist of the present invention described in the claims.

  DESCRIPTION OF SYMBOLS 1 ... Duplex computer, 1a ... 1 system computer, 1b ... 2 system computer, 2 ... Duplex network relay apparatus, 2a ... 1 system network relay apparatus, 2b ... 2 system network relay apparatus, 3 ... Duplex network Connection device, 3a ... 1 system network connection device, 3b ... 2 system network connection device, 4a ... LAN between relay devices, 4b ... control line, 5 ... duplex network, 5a ... 1 system network, 5b ... 2 system network, DESCRIPTION OF SYMBOLS 6 ... Network monitoring apparatus, 7 ... Duplex network system, 10 ... Two branch connection apparatus, 11-13 ... Transmission path, 14 ... Reception frame transmission control part, 15 ... Buffer memory, 20 ... Network switch, 21 ... Frame transmission Control unit, 21a ... transmission path, 22 ... path switching unit, 22a, 22b ... transmission path, 23 ... monitoring frame transmission control unit 24 ... working system connection switch control unit, 25 ... overlapping frame discard processing unit, 26 ... reception management table, 27 ... transmission management table, 28 ... buffer memory

Claims (4)

A computer apparatus in a network, which is configured by connecting two computer apparatuses, one of which is installed at a plurality of locations and the other of which is a slave, by a duplex network of a 1-system network and a 2-system network. Is a fault monitoring system applied to a network system that transmits and receives frames between
The network system includes:
Two computers are prepared for each computer device, the frame received from the computer device is branched and transmitted to one and the other plural paths, and the frame received from one and the other plural paths is connected to the computer A two-branch connection device transmitting to the device;
A 1-system network relay device that relays a frame sent from the two-branch connection device to one path and sends a frame received from the network side to the connected two-branch connection device;
A two-system network relay device that relays a frame sent from the two-branch connection device to the other path and sends a frame received from the network side to the connected two-branch connection device;
A 1-system network connection device for transmitting a frame received from the 1-system network relay device to the 1-system network and transmitting a frame received from the 1-system network to the 1-system network relay device;
A second-system network connection device for transmitting a frame received from the second-system network relay device to the second-system network and transmitting a frame received from the second-system network to the second-system network relay device;
In the fault monitoring system for a network system in which the one-system network relay device and the second-system network relay device operate as one master and the other as a slave,
Each of the two-branch connection devices monitors the failure of the first-system network relay device and the second-system network relay device, and becomes a slave when a failure occurs in one of the master network relay devices. A fault monitoring system for switching the other network relay device to a master . The first-system network relay device and the second-system network relay device monitor each other for failures, and when a failure occurs in one of the network relay devices serving as a master, the other network relay device serving as a slave serves as a master. The fault monitoring system according to claim 1, wherein the fault monitoring system is switched to . Furthermore, a network monitoring device connected to the system 1 network and the system 2 network is provided,
The network monitoring device monitors a failure of the first-system network relay device and the second-system network relay device via the first-system network or the second-system network, and there is a failure in one of the master network relay devices. 3. The fault monitoring system according to claim 2, wherein when the error occurs, control is performed to switch the other network relay device that is set as a slave to the master . The 1-system network connection device and the 2-system network connection device operate independently for each network connection device, and the 2-branch connection devices also operate independently for each 2-branch connection device. 3. The fault monitoring system according to 3.

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