JP2016213694A - Communication device, communication network, and communication network fault diagnosis method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the cause of a fault occurring on a communication network to be diagnosed automatically.SOLUTION: A communication device (slave station 2) according to one aspect of the present invention relates to a communication device used in a communication network NW adopting a bucket brigade method. The communication device comprises: a relay processing unit 21 capable of passive operation that lets a signal arriving at its station pass without amplifying it and active operation that amplifies and relays a signal arriving at its station; and a control unit 30 capable of forcibly making the relay processing unit 21 perform both first switch from the active operation to the passive operation and second switch from the passive operation to the active operation.SELECTED DRAWING: Figure 2

Description

The present invention relates to a communication device, a communication network including the communication device, and a failure diagnosis method for the communication network.
Specifically, the present invention relates to a technique for automatically diagnosing the cause of a failure in a communication network including a communication device capable of bypassing a signal by passive operation.

In a ring topology optical communication network, a technique for preventing the communication of the entire network from being disabled by providing each communication device with an optical switch that bypasses an optical signal to an adjacent node in the event of a power failure or the like is already known. (See Patent Document 1).
Also, a technique for detecting a bypass node in which a failure has occurred by circulating a test frame indicating the node number of the local station to the slave station every time the local station passes through the ring network is already known (patent) Reference 2).

Japanese Patent Laying-Open No. 2005-210818 JP-A-4-257142

In Patent Document 1, there is no means for diagnosing the cause of the communication node becoming a bypass node. For this reason, even if a communication node becomes a bypass node due to some failure, the network administrator cannot detect which communication node has become the bypass node.
If the communication network is relatively small, the failed communication node may be identified. For example, in the case of a communication network in which the distance of the link is large and the communication nodes are scattered in remote locations, the failed communication node may be identified. It is difficult to identify.

On the other hand, since the communication node that has become the bypass node can be detected in advance in Patent Document 2, there is an advantage that maintenance of the communication network after the occurrence of a failure is easier than in the case of Patent Document 1.
However, since Patent Document 2 only detects a communication node that has changed to a bypass node, the network administrator can explain the cause of a failure that has occurred in the communication network, such as a reception abnormality or transmission abnormality of the communication node, or a transmission path failure. It cannot be detected.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to automatically diagnose the cause of a failure occurring in a communication network.

  (1) A communication apparatus according to an aspect of the present invention is a communication apparatus used in a communication network that employs a bucket relay system, and includes a passive operation that allows a signal that has reached its own station to pass through without being amplified; A relay processing unit capable of performing an active operation of amplifying and relaying a signal that has reached the station, a first switching from the active operation to the passive operation, and a second switching from the passive operation to the active operation A control unit capable of forcibly executing both of them on the relay processing unit.

(4) A communication network according to an aspect of the present invention is a communication network including a communication path in which four or more communication nodes communicating in a bucket relay system are arranged in series, and the communication path includes: Communication adjacent to each other, which is a communication device capable of forcibly executing both the first switching from the active operation to be defined to the passive operation defined below and the second switching from the passive operation to the active operation. Contains nodes.
Active operation: Operation to amplify and relay the signal that has reached its own station Passive operation: Operation to pass the signal that has reached its own station without amplification

  (5) A failure diagnosis method according to an aspect of the present invention is the communication network failure diagnosis method described above, and is defined below as a first step of detecting communication failure of one link included in the communication path. A second step in which another communication node executes communication confirmation while at least one of the second and third nodes among the first to fourth nodes is in the passive operation; and And a third step of determining a cause of communication failure of the link based on a result of the communication confirmation.

First node: A communication node adjacent to the second node and not directly connected to the incommunicable link Second node: One communication node directly connected to the incommunicable link Third node: Directly connected to the incommunicable link The other communication node Fourth node: a communication node that is adjacent to the third node and is not directly connected to an incommunicable link

  According to the present invention, it is possible to automatically diagnose the cause of a failure occurring in a communication network.

It is a figure which shows the connection form of the communication system which concerns on embodiment of this invention. It is a block diagram which shows the internal structure of a master station and a slave station. It is a flowchart of the failure diagnosis process of a communication network. It is a flowchart of the failure diagnosis process of a communication network. It is explanatory drawing of the failure diagnosis process of a communication network. (A) is a table summarizing the processing content of the determination processing Di, (b) is a table summarizing the processing content of the determination processing Di + 1, and (c) is a table summarizing the processing content of the determination processing Dj. (A) is a table summarizing the logic of the first specific process, and (b) is a table summarizing the logic of the second specific process. It is a block diagram which shows the modification of the internal structure of a sub_station | mobile_unit. It is a flowchart of another failure diagnosis process of a communication network.

<Outline of Embodiment of the Present Invention>
Hereinafter, an outline of embodiments of the present invention will be listed and described.
(1) The communication device according to the present embodiment is a communication device used in a communication network that employs a bucket relay system, and performs a passive operation that allows a signal that has reached the local station to pass through without being amplified, and reaches the local station. A relay processing unit capable of performing an active operation for amplifying and relaying the generated signal, a first switching from the active operation to the passive operation, and a second switching from the passive operation to the active operation, A control unit that can be forcibly executed with respect to the relay processing unit.

According to the communication apparatus of the present embodiment, the control unit can forcibly execute both the first switching and the second switching with respect to the relay processing unit.
For this reason, the communication device of this embodiment is adopted as a communication node of a communication network, the communication node directly connected to the incommunicable link is forcibly passively operated, and other communication nodes perform communication confirmation, thereby enabling link communication. The cause of the impossibility can be determined. Therefore, it becomes possible to automatically diagnose the cause of the failure occurring in the communication network.

(2) The communication apparatus according to the present embodiment further includes a timer that locally measures the passage of time of the own station, and the control unit performs the second switching when the count value of the timer reaches a predetermined value. It is preferable to carry out.
In this case, the return means from the passive operation to the active operation can be easily implemented by a regular timer. That is, it is not necessary to provide a special circuit for configuring the return means from the passive operation to the active operation, and the communication device can be manufactured at low cost.

(3) In the communication apparatus according to the present embodiment, the communication device further includes a receiving unit capable of receiving a control signal from the outside during the passive operation of the relay processing unit, and the control unit receives the control signal received by the receiving unit. Based on this, the second switching may be executed.
In this case, the circuit configuration is complicated as much as the reception unit is required. However, since the second switching is performed based on the control signal received during the passive operation, it is possible to reliably return from the passive operation to the active operation. it can.

(4) The communication network of the present embodiment is a communication network including a communication path in which four or more communication nodes communicating in a bucket relay system are arranged in series, and the communication path includes an active defined as follows. Includes communication nodes adjacent to each other, which are communication devices that can forcibly execute both the first switching from the operation to the passive operation defined below and the second switching from the passive operation to the active operation. It is.
Active operation: Operation to amplify and relay the signal that has reached its own station Passive operation: Operation to pass the signal that has reached its own station without amplification

According to the communication network of the present embodiment, the communication device is capable of forcibly executing both the first switching and the second switching on a communication path in which four or more communication nodes are arranged in series. Communication nodes adjacent to each other are included.
For this reason, the cause of the link communication failure can be determined by forcibly passively operating the communication node directly connected to the incommunicable link and confirming communication with other communication nodes. Therefore, it becomes possible to automatically diagnose the cause of the failure occurring in the communication network.

(5) Specifically, if the communication network of the present embodiment is employed, the following failure diagnosis method can be employed.
That is, the failure diagnosis method of the present embodiment is the above-described communication network failure diagnosis method, and includes a first step of detecting communication inability of one link included in the communication path, and first to first defined above. Among the fourth nodes, while at least one of the second and third nodes is in the passive operation, the second step in which another communication node executes communication confirmation, and the communication confirmation of the other communication node. And a third step of determining a cause of communication failure of the link based on the result.

First node: A communication node adjacent to the second node and not directly connected to the incommunicable link Second node: One communication node directly connected to the incommunicable link Third node: Directly connected to the incommunicable link The other communication node Fourth node: a communication node that is adjacent to the third node and is not directly connected to an incommunicable link

  According to the failure diagnosis method of the present embodiment, while at least one of the second and third nodes among the first to fourth nodes is in a passive operation, another communication node performs communication confirmation (second Step) Since the cause of the communication failure of the link is determined based on the result of the communication confirmation of the other communication node, the cause of the failure occurring in the communication network can be automatically diagnosed.

  (6) In the failure diagnosis method of the present embodiment, the second step includes a process in which the second node and the fourth node perform communication confirmation while the third node is in the passive operation. The third step includes a process of determining at least one of reception abnormality and transmission abnormality of the second node based on a result of communication confirmation between the second node and the fourth node. It is preferable that

  In this way, since at least one of the reception abnormality and transmission abnormality of the second node can be determined, a failure relating to the second node can be automatically diagnosed.

  (7) In the failure diagnosis method of the present embodiment, the second step includes a process in which the first node and the third node execute communication confirmation while the second node is in the passive operation. The third step includes a process of determining at least one of reception abnormality and transmission abnormality of the third node based on a result of confirmation of communication between the first node and the third node. It is preferable that

  In this way, since at least one of reception abnormality and transmission abnormality of the third node can be determined, a failure relating to the third node can be automatically diagnosed.

  (8) In the failure diagnosis method of the present embodiment, in the second step, the first node and the fourth node perform communication confirmation while the second node and the third node are in the passive operation. Preferably, a process is included, and the third step preferably includes a process of determining whether or not there is an abnormality in the link based on a result of communication confirmation between the first node and the fourth node.

  In this way, since it is possible to determine the presence or absence of a link abnormality, it is possible to automatically diagnose a failure relating to the link (such as a broken transmission line).

<Details of Embodiment of the Present Invention>
Hereinafter, details of embodiments of the present invention will be described with reference to the drawings. In addition, you may combine arbitrarily at least one part of embodiment described below.
A PDU (Protocol Data Unit) used in layer 2 communication is often referred to as a “frame”, and a PDU used in layer 3 communication is often referred to as a “packet”. However, in the following description, “packet” and “frame” "Is used in the meaning of PDU.

[Overall configuration of communication system]
FIG. 1 is a diagram showing a connection form of a communication system according to an embodiment of the present invention.
As shown in FIG. 1, the communication system of the present embodiment includes a communication network NW including a plurality of communication nodes N0 to Nn provided to implement, for example, distribution network automation, and one communication node N0 (master station). 1) and a central device 4 communicatively connected.

In the following description, when common items of the communication nodes N0 to Nn are described, “N” is used as a representative code of the communication nodes N0 to Nn.
In the communication network NW of FIG. 1, each communication node N is communicably connected to an adjacent node through a transmission path 3. The communication medium constituting the transmission path 3 can employ a transmission line such as a one-core or two-core optical fiber or a metal line. However, it is assumed that the transmission line 3 of this embodiment is a single-core optical fiber.

In the communication network NW of FIG. 1, the communication node N0 indicated by a square mark is “master station 1”, and the other communication nodes N1 to Nn indicated by circles are “slave station 2”.
For the communication node Ni of the slave station 2 with the node number i of 1 to n, the “child station i−1”, “slave station i”, “slave station i + 1” Sometimes referred to as “slave station i + 2”.

The communication node N0 of the master station 1 and the communication nodes N1 to Nn of the slave station 2 are connected in a daisy chain with adjacent nodes by the transmission path 3, and ring topology (N0 → N1 → N2 → N3 →… Ni →… Nn−1 → Nn → N0) communication network NW.
Therefore, the communication path of the communication network NW is made redundant in the clockwise direction and the counterclockwise direction. For example, the communication path from the communication node N3 to the communication node N0 is made redundant into two communication paths of N3 → N4 →... Ni →... Nn → N0 and N3 → N2 → N1 → N0. The

The communication network NW of this embodiment is used for the automation of the power distribution network. That is, the communication network NW is used for, for example, remote control of power distribution devices such as a plurality of high voltage switches 6 managed by an electric power company and remote sensing related to the power distribution devices.
Therefore, each slave station 2 is installed in the vicinity of the switch 6 (for example, the upper end portion of the utility pole) corresponding to the switch 6 of the distribution line 5 constituting the distribution network. Further, the communication node N0 of the master station 1 is installed together with the central device 4 in a substation of the distribution system.

However, the central device 4 and the master station 1 may be installed in different locations, and the master station 1 may be connected to the central device 4 via a higher-level network such as the Internet.
In FIG. 1, for simplification of illustration, only one slave station 2 (communication node N3) is connected to the switch 6, but in reality, all the slave stations 2 (communication nodes N1 to N1) are connected. Nn) is connected to the switch 6.

The slave station 2 controls the switching operation of the switch 6 according to a control signal included in the communication frame of the master station 1 as a transmission source. The slave station 2 also monitors the open / close state and failure of the switch 6, and transmits a communication frame addressed to the master station 1 including the monitoring information to the adjacent node.
The switch 6 has a sensor for measuring the voltage, current, power factor and the like of the distribution line 5. When the slave station 2 acquires the measurement information from the sensor, the slave station 2 transmits a communication frame addressed to the master station 1 including the measurement information to the adjacent node.

The central device 4 is composed of a computer device capable of IP communication such as a server computer or a personal computer. The central device 4 can communicate with a predetermined slave station 2 by IP communication with the master station 1 and communication between the communication nodes N of the communication network NW.
Accordingly, when the central apparatus 4 inputs a control signal addressed to a specific slave station 2 to the master station 1, the master station 1 transmits a communication frame addressed to the specific slave station 2 including the input control signal to the adjacent node. . Thereby, the central apparatus 4 can transmit a control signal to the slave station 2 corresponding to the predetermined switch 6.

When the master station 1 receives a communication frame addressed to itself including at least one of monitoring information and measurement information from the slave station 2, the master station 1 extracts the information from the received communication frame and transfers the extracted information to the central device 4. To do.
Thereby, the central apparatus 4 can collect at least one information of monitoring information and measurement information about each switch 6 from all the slave stations 2 included in the communication network NW.

As described above, the communication network NW according to the present embodiment is used as a communication network in which an administrator who operates the central device 4 remotely controls a plurality of target devices (in the illustrated example, the high-voltage switch 6 of the distribution network). .
Accordingly, when the slave station 2 is installed for each target device, the number of nodes included in the network increases according to the number of target devices. For example, when remotely controlling a plurality of switches 6 managed by one substation, the number of slave stations 2 corresponding to one master station 1 is several hundred.

In the example of FIG. 1, the slave station 2 and the switch 6 correspond one-to-one. However, a connection form in which one slave station 2 and a plurality of switches 6 are associated may be used. A connection configuration in which the slave station 2 and one switch 6 are associated with each other may be used.
Further, the topology of the communication network NW is not limited to the single ring shape shown in FIG. 1, but may be a topology including a plurality of rings, a chain shape or a chain shape having branches (not shown). ).

[Communication method of communication network]
Each communication node N configuring the communication network NW relays the communication frame received from the adjacent node according to a predetermined path control protocol, thereby transferring the communication frame within the communication network NW by the “bucket relay method”.

That is, the communication node N has a routing table (including accompanying information such as the number of hops to the destination and the expiration date of the route) that determines from which transmission port the communication frame received from the adjacent node is transmitted. .
Further, the communication node N may store topology information of the communication network NW for determining the routing table. Then, the communication node N determines the transmission destination of the communication frame received from the adjacent node according to the routing table held by itself.

Specifically, when a communication frame received from an adjacent node (hereinafter referred to as “reception frame”) is a unicast addressed to itself, the communication node N takes in the received frame and relays it to the communication network NW. do not do.
If the received frame is unicast not addressed to itself, the communication node N determines a transmission port corresponding to the destination described in the received frame from the routing table, and transmits the received frame from the determined transmission port.

When the received frame is a multicast addressed to itself, the communication node N takes the received frame into itself, determines a transmission port corresponding to another destination described in the received frame from the routing table, and determines from the determined transmission port. Send the received frame.
When the received frame is a broadcast addressed to itself, the communication node N takes the received frame into itself and transmits the received frame from all the transmission ports.

A communication frame used in the communication network NW defines an area of TTL (Time To Live) information that is incremented every time the communication frame is transferred.
Therefore, the communication node N discards a communication frame whose number of transfers described in the TTL information is a predetermined value or more. As a result, occurrence of a loop frame in the communication network NW is prevented.

The setting of the routing table for the communication node N may be fixedly performed by an operation input from a personal computer or the like or a control frame received from the central device 4 (static routing). However, the communication node N may set the routing table autonomously and dynamically by the learning function (dynamic routing).
Examples of the latter dynamic routing protocol include, for example, AODV (Ad hoc On-demand Distance Vector), RIP (Routing Information Protocol), OSPF (Open Shortest Path First), and OLSR (Optimized Link State Routing). is there.

In the communication network NW of the present embodiment, the communication nodes N1 to Nn of the slave station 2 are driven by power supply from the distribution line 5, but are switched to a passive node that bypasses the optical signal with no power, 24 (see FIG. 2) is provided inside.
That is, when the power supply from the distribution line 5 is interrupted due to a power failure or the like, each slave station 2 switches the optical signal transmission path to the optical fiber (bypass path 26 in FIG. 2) provided in the local station. Optical switches 23 and 24 that can

Thereby, each slave station 2 can be changed to a passive node that passively passes through its own station without amplifying the optical signal.
For this reason, even if a power failure occurs in a part of the distribution network, the slave station 2 located in that area can bypass the optical signal to the adjacent node, and transmission of the optical signal in the communication network NW is ensured. The

[Configuration of slave stations]
FIG. 2 is a block diagram showing an internal configuration of the master station 1 and the slave station 2.
As shown in FIG. 2, the slave station 2 includes a relay processing unit 21 and a power supply unit 22.
The power supply unit 22 includes an AC / DC converter therein. The power supply unit 22 converts alternating current (for example, 100V alternating current) supplied from the distribution line 5 via a transformer into a predetermined direct current, and supplies the converted direct current voltage to the relay processing unit 21.

The relay processing unit 21 includes two optical switches 23 and 24, and a normal path 25 and a bypass path 26 arranged in parallel between the optical switches 23 and 24. The bypass path 26 is made of the same communication medium (optical fiber) as the transmission path 3.
The normal path 25 has a circuit configuration in which a relay unit 29 is connected in series to two optical interfaces 27 and 28. A control unit 30 is connected to the relay unit 29, and a timer 31 is connected to the control unit 30.

  Although FIG. 2 illustrates the case where the control unit 30 is mounted inside the relay processing unit 21, the control unit 30 and the timer 31 may be configured by a control circuit different from the relay processing unit 21. Good.

The optical switches 23 and 24 are each composed of a 1-input × 2-output MEMS (Micro Electro Mechanical Systems) type optical switch or a mechanical optical switch.
The communication side ports P1 of the optical switches 23 and 24 are connected to optical fibers connected to the optical input / output terminals of the optical interfaces 27 and 28 constituting the normal path 25, respectively. Each end of the bypass path 26 is connected to the bypass side port P2 of the optical switches 23 and 24, respectively.

The optical switches 23 and 24 switch the output port to the bypass side port P2 when power is not supplied from the power supply unit 22 due to a power failure or a failure of the power supply unit 22.
In this case, the optical signal that has reached the bypass side port P2 of the optical switch 23 from one adjacent node (for example, the left side in FIG. 2) passes through the bypass path 26 as it is, and passes from the bypass side port P2 of the optical switch 24 to the other ( For example, it is transmitted to the adjacent node on the right side in FIG.

Conversely, an optical signal that has reached the bypass-side port P2 of the optical switch 24 from the other adjacent node (for example, the right side in FIG. 2) passes through the bypass path 26 as it is and passes through the bypass-side port P2 of the optical switch 23 ( For example, it is transmitted to the adjacent node on the left side of FIG.
Accordingly, the relay processing unit 21 of the slave station 2 can perform a passive operation of bypassing the optical signal to the adjacent node by allowing the optical signal reaching the local station to pass therethrough without being amplified by the relay unit 29.

The optical interfaces 27 and 28 are optical transceivers capable of mutual conversion between optical signals and electrical signals.
The optical interfaces 27 and 28 convert the optical signal input from the communication side port P <b> 1 into an electrical signal, and send the converted electrical signal to the relay unit 29. The optical interfaces 27 and 28 convert the electrical signal input from the relay unit 29 into an optical signal, and send the converted optical signal to the transmission line 3 connected to the communication side port P1.

The relay unit 29 reproduces a communication frame from the electrical signals acquired from the optical interfaces 27 and 28, and performs a predetermined relay process according to the above-described path control protocol on the reproduced communication frame. In addition, the optical interfaces 27 and 28 set as transmission destinations by the relay processing transmit optical signals with a light amount that can reach the adjacent nodes.
Therefore, the relay processing unit 21 of the slave station can perform an active operation of amplifying the optical signal reaching the local station and relaying it according to a predetermined path control protocol.

When the reproduced communication frame is a control frame for requesting a failure determination for which the master station 1 is the transmission source (determination request R in FIG. 5; hereinafter, also referred to as “determination request frame”), The reproduced determination request frame is transferred to the control unit 30.
The control unit 30 can control the switching of the output ports of the optical switches 23 and 24 according to the instruction content in the determination request frame.

Specifically, when the current time reaches the passive switching time specified by the determination request frame, the control unit 30 forcibly switches the output port of the optical switches 23 and 24 to the bypass side port P2 (hereinafter referred to as “first” Also called “switch”.)
Further, the control unit 30 forcibly switches the output ports of the optical switches 23 and 24 to the communication side port P1 when the current time becomes the active switching time specified by the determination request frame (hereinafter referred to as “second switching”). Say.).

As described above, the control unit 30 forcibly operates the local station as a passive node by switching the output ports of the optical switches 23 and 24 of the local station to the bypass side port P1 at the time designated by the master station 1. (Forced bypass function).
In addition, the control unit 30 forcibly returns the local station to the active node in normal operation by switching the output ports of the optical switches 23 and 24 of the local station to the communication side port P2 at the time designated by the master station 1. (Forced return function).

The timer 31 includes a clock counter that synchronizes time with a timer (not shown) held by the master station 1.
The control unit 30 activates or passively activates the local station depending on whether the count value measured locally by the timer 31 of the local station has passed a predetermined value (for example, the passive switching time or the active switching time specified by the master station 1). The operation mode is determined.

The control unit 30 cooperates with the next child station 2 of the adjacent node or further next child station 2 while the own station is actively operating and the adjacent node is passively operated by forced bypass. Thus, for example, it is possible to execute a failure determination process using communication confirmation using a Hello packet (failure determination function).
When executing the above-described determination process, the control unit 30 generates and generates a control frame addressed to the master station 1 including the determination result (determination responses A1 to A5 in FIG. 5: hereinafter also referred to as “determination response frame”). The determined response frame is transmitted to the relay unit 29.

[Configuration of master station]
As shown in FIG. 2, the master station 1 includes a relay processing unit 11, a power supply unit 12, and a control unit 13.
The power supply unit 12 includes an AC / DC converter therein. The power supply unit 12 converts alternating current (for example, 100 V alternating current) supplied from the distribution line 5 through a transformer into a predetermined voltage direct current, and supplies the converted direct current voltage to the relay processing unit 11 and the control unit 13. To do.

The relay processing unit 11 includes a communication interface capable of executing both local communication with the slave station 2 in the communication network NW and external communication with the central apparatus 4.
The relay processing unit 11 has at least two optical communication ports. These optical communication ports are connected to transmission paths 3 that respectively communicate with adjacent slave stations 2. The relay processing unit 11 reproduces a communication frame from an electrical signal obtained by photoelectrically converting the optical signal received from the adjacent slave station 2, and performs relay processing according to the above-described path control protocol on the communication frame.

In the relay processing unit 11, the reproduced communication frame is a control frame (detection notification K in FIG. 5: hereinafter also referred to as “detection notification frame”) in which the slave station 2 notifies “link break” with the adjacent node. In this case, the reproduced detection notification frame is transferred to the control unit 13.
When acquiring the detection notification frame, the control unit 13 determines determination frames addressed to a plurality of slave stations 2 (for example, slave stations i-1, i, i + 1, i + 2 in FIG. 5) including the slave station 2 of the transmission source (FIG. 5). The determination request R) is generated, and the generated determination request frame is transmitted to the relay processing unit 11.

When the reproduced communication frame is a control frame including the determination result determined by the slave station 2 (determination responses A1 to A5 in FIG. 5), the relay processing unit 11 passes the reproduced determination response frame to the control unit 13. .
Based on the determination result included in the determination response frame, the control unit 13 performs a process for identifying the cause (failure location) of the link disconnection for the link whose disconnection is detected by the detection notification frame.

  The control unit 13 generates a final diagnosis result from the determination result acquired from the slave station 2 and the result of the above specific process, and transmits a communication frame addressed to the central apparatus 4 including the generated diagnosis result to the relay processing unit 11 to transmit.

[Communication network failure diagnosis processing]
3 and 4 are flowcharts of the failure diagnosis process of the communication network NW, which is executed by the master station 1 and the plurality of slave stations 2 in cooperation. FIG. 5 is an explanatory diagram of the failure diagnosis process.
Hereinafter, the contents of the failure diagnosis process of the present embodiment will be described with reference to FIGS. In the following description, the processing entities are the master station 1 and the slave station 2, but the actual processing entities are the control unit 13 of the master station 1 and the control unit 30 of the slave station 2 shown in FIG. .

In the present embodiment, when communication failure (link disconnection) occurs in the transmission path (hereinafter simply referred to as “link”) between the slave station i and the slave station i + 1, and the slave station i detects this communication failure. (See FIG. 1 and FIG. 5).
For example, when the slave station i cannot transmit / receive a Hello packet to / from the slave station i + 1, or when communication with the slave station i + 1 is not performed after a predetermined time, the link failure with the slave station i + 1 occurs. Is detected.

As shown in FIGS. 3 and 5, in the communication between the slave station i and the slave station i + 1, when the slave station i detects a link break in one or both directions (step ST1), the slave station i detects the link break. Is sent to the master station 1 (step ST2).
The detection notification K includes identification information (such as a link number) of the transmission path that has become unable to communicate. The slave station i transmits the detection notification K in a direction that does not include the transmission path in which the link breakage occurs (counterclockwise in the example of FIG. 1).

  When the master station 1 receives the detection notification K, the master station 1 specifies the link from which the link disconnection is detected from the identification information included in the detection notification K, and the four slave stations included in the serial communication path in which this link is the central section A determination request R for requesting a failure determination process is transmitted to i-1, i, i + 1, i + 2 (step ST3).

The communication node N set as the transmission destination of the determination request R is simply defined as follows.
Slave station i-1: Communication node adjacent to slave station i and not directly connected to incapable link Slave station i: One communication node directly connected to a link incapable of communication Slave station i + 1: Directly connected to a link incapable of communication The other communication node slave station i + 2: a communication node adjacent to the slave station i + 1 and not directly connected to a link where communication is impossible

The master station 1 transmits a determination request R in a direction that does not include the transmission path in which the link break has occurred. Specifically, the master station 1 transmits a determination request R addressed to the slave stations i−1 and i in the clockwise direction, and transmits a determination request R addressed to the slave stations i + 1 and i + 2 in the counterclockwise direction.
As shown in FIGS. 3 to 5, the determination process executed by the slave station 2 includes three types of determination processes Di, Di + 1, and Dj.

The determination process Di is a process in which the three slave stations i, i + 1, i + 2 cooperate to check whether there is a failure related to the slave station i.
The determination process Di + 1 is a process in which the three slave stations i-1, i, i + 1 cooperate to check whether or not there is a failure related to the slave station i + 1.
The determination process Dj is a process in which the four slave stations i−1, i, i + 1, i + 2 cooperate to check whether the link between the slave station i and the slave station i + 1 is broken.

The order of the determination processes Di, Di + 1, Dj shown in FIGS. 3 to 5 is an example, and the order of the determination processes Di, Di + 1, Dj, such as Di + 1 → Dj → Di + 1, can be arbitrarily changed. Further, only a part of the three determination processes Di, Di + 1, Dj may be performed.
In the present embodiment, it is assumed that all the determination processes Di, Di + 1, Dj are executed, and that each slave station 2 performs the determination processes Di, Di + 1, Dj in the order of Di → Di + 1 → Dj.

The determination request R includes four times t1 to t4 shown in FIG. Time t1 is the start time of the determination process Di. Time t2 is the start time of the determination process Di + 1. The time t2 is also a deadline time at which the determination process Di must be completed by this time at the latest.
Time t3 is the start time of the determination process Dj. Time t3 is also a deadline time at which the determination process Di + 1 must be completed by this time at the latest. Time t4 is a deadline time at which the determination process Dj must be completed by this time at the latest.

The above is summarized as follows.
The determination process Di is performed in a time zone of t1 ≦ t <t2.
The determination process Di + 1 is performed in a time zone of t2 ≦ t <t3.
The determination process Dj is performed in a time zone of t3 ≦ t <t4.
The times t1 to t4 may be absolute times that are synchronized between the master station 1 and the slave station 2, or the timer 31 of each slave station 2 counts up or down when the determination request R is received. It may be a relative time to start.

The three slave stations i, i + 1, i + 2 execute the determination process Di between time t1 and time t2 designated by the master station 1. Further, the determination responses A1 and A2 including the determination result by the determination process Di are transmitted to the master station 1 by time t2.
Similarly, the three slave stations i-1, i, i + 1 execute the determination process Di + 1 between time t2 and time t3 designated by the master station 1. Also, the determination responses A3 and A4 including the determination result by the determination process Di + 1 are transmitted to the master station 1 by time t3.

Further, the four slave stations i-1, i, i + 1, i + 2 execute the determination process Dj between the time t3 and the time t4 designated by the parent station 1. The determination response A5 including the determination result by the determination process Dj is transmitted to the master station 1 by time t4.
The state transition of the slave station i and the slave station i + 1 according to the progress of the three determination processes Di, Di + 1, Dj will be described in time series as follows.

The slave station i transitions to the active node at time t1, performs the first switching at time t2 to become a passive node, transitions to the passive node at time t3, and performs the second switching at time t4 to become the active node. Return.
The slave station i + 1 performs the first switching at time t1 to become a passive node, performs the second switching at time t2, returns to the active node, performs the first switching at time t3, and becomes the passive node, and the second switching at time t4. Switch back to the active node.

As shown in FIG. 3, the determination process Di is a state in which a Hello packet between the slave stations i and i + 2 at both ends is forcibly bypassed in the middle slave station i + 1 among the three slave stations i, i + 1 and i + 2. This is performed by checking the communication (step ST4).
That is, in the time zone of t1 ≦ t <t2 that is the execution period of the determination process Di, the slave station i + 1 is a passive node and the slave stations i and i + 2 at both ends are active nodes, and the slave stations i and i at both ends that are active nodes. i + 2 transmits and receives Hello packets to each other.

  In the determination process Di, the slave station i determines whether or not the Hello packet from the other party cannot be received (step ST5).

If the determination in step ST5 is affirmative, the slave station i generates a determination result indicating that the reception function of the slave station i is abnormal (step ST6), and receives the determination response A1 including the generated determination result as the parent response. Transmit to the station 1 (step ST11).
If the determination in step ST5 is negative, the slave station i generates a determination result indicating that the reception function of the slave station i is normal (step ST7), and receives the determination response A1 including the generated determination result as the parent response. Transmit to the station 1 (step ST11).

  In the determination process Di, the slave station i + 1 determines whether or not the Hello packet from the other party cannot be received (step ST8).

If the determination in step ST8 is affirmative, the slave station i + 2 generates a determination result indicating that the transmission function of the slave station i is abnormal (step ST9), and receives a determination response A2 including the generated determination result as a parent. Transmit to the station 1 (step ST12).
If the determination in step ST8 is negative, the slave station i + 2 generates a determination result indicating that the transmission function of the slave station i is normal (step ST10), and receives the determination response A2 including the generated determination result as a parent. Transmit to the station 1 (step ST12).

FIG. 6A is a table summarizing the processing contents of the determination processing Di.
As shown in FIG. 6 (a), the slave station i determines whether the reception function of the slave station i as a local station is normal or abnormal according to the success or failure of packet reception in the slave station i as a local station. A determination response A1 including the determination result is transmitted to the master station 1.

In addition, the slave station i + 2 determines whether the transmission function of the slave station i that is the counterpart station is normal or abnormal according to the success or failure of packet reception in the slave station i + 2 that is the local station, and the determination response A2 including the determination result Is transmitted to the master station 1.
When the slave station i + 2 cannot receive the Hello packet, the reason for determining that the slave station i has a transmission abnormality is presumed that the transmission / reception function of the slave station i + 2 that is not directly connected to the broken link is normal. This is because that.

As shown in FIG. 4, the determination process Di + 1 is performed between the slave stations i-1, i + 1 at both ends in a state where the middle slave station i among the three slave stations i-1, i, i + 1 is forcibly bypassed. This is done by checking the communication of the Hello packet (step ST13).
That is, in the time period up to t2 ≦ t <t3, which is the execution period of the determination process Di + 1, the child station i is a passive node and the child stations i−1 and i + 1 at both ends are active nodes and the children at both ends that are active nodes. Stations i-1 and i + 1 transmit and receive Hello packets to each other.

  In the determination process Di + 1, the slave station i + 1 determines whether or not the Hello packet from the other party cannot be received (step ST14).

If the determination in step ST14 is affirmative, the slave station i + 1 generates a determination result indicating that the reception function of the slave station i + 1 is abnormal (step ST15), and receives a determination response A3 including the generated determination result as a parent. Transmit to the station 1 (step ST20).
If the determination in step ST14 is negative, the slave station i + 1 generates a determination result indicating that the reception function of the slave station i + 1 is normal (step ST16), and receives the determination response A3 including the generated determination result as a parent. Transmit to the station 1 (step ST20).

  In the determination process Di + 1, the slave station i-1 determines whether or not the Hello packet from the other party cannot be received (step ST17).

If the determination in step ST17 is affirmative, the slave station i-1 generates a determination result indicating that the transmission function of the slave station i + 1 is abnormal (step ST18), and a determination response A4 including the generated determination result Is transmitted to the master station 1 (step ST21).
If the determination in step ST17 is negative, the slave station i-1 generates a determination result indicating that the transmission function of the slave station i + 1 is normal (step ST19), and a determination response A4 including the generated determination result Is transmitted to the master station 1 (step ST21).

FIG. 6B is a table summarizing the processing contents of the determination process Di + 1.
As shown in FIG. 6B, the slave station i + 1 determines whether the reception function of the slave station i + 1 is normal or abnormal according to the success or failure of the packet reception in the slave station i + 1 as its own station. A determination response A3 including the determination result is transmitted to the master station 1.

Further, the slave station i-1 determines whether the transmission function of the slave station i + 1, which is the counterpart station, is normal or abnormal according to the success or failure of packet reception in the slave station i-1, which is its own station. A determination response A4 including the request is transmitted to the master station 1.
When the slave station i-1 cannot receive the Hello packet, it is determined that the transmission error of the slave station i + 1 is normal because the transmission / reception function of the slave station i-1 that is not directly connected to the broken link is normal. This is because it is estimated that there is.

As shown in FIG. 4, in the determination process Dj, two slave stations i-1, i + 1 out of the four slave stations i-1, i, i + 1, i + 2 are forcibly bypassed. This is performed by checking the communication of the Hello packet between 1 and i + 2 (step ST22).
That is, in the time period up to t3 ≦ t <t4, which is the execution period of the determination process Dj, the slave stations i and i + 1 are passive nodes, and the slave stations i−1 and i + 2 at both ends are active nodes, and both ends are active nodes. Slave stations i−1 and i + 2 transmit and receive Hello packets to each other.

  In the determination process Dj, the slave station i-1 determines whether or not the Hello packet from the other party cannot be received (step ST23).

If the determination in step 23 is affirmative, the slave station i-1 generates a determination result indicating that the transmission path is abnormal (step ST24), and sends a determination response A5 including the generated determination result to the master station 1 (Step ST26).
If the determination in step ST23 is negative, the slave station i-1 generates a determination result indicating that the transmission path is normal (step ST26), and sends a determination response A5 including this determination result to the master station 1. Transmit (step ST26).

FIG. 6C is a table summarizing the processing contents of the determination processing Dj.
As shown in FIG. 6 (c), the slave station i-1 determines whether the transmission path between the slave station i and the slave station i + 1 is normal or abnormal depending on the success or failure of packet reception in the slave station i-1 that is its own station. And a determination response A5 including the determination result is transmitted to the master station 1.

  Note that, instead of the slave station i-1, the slave station i + 2 executes the processing from step ST22 to ST25 based on the success or failure of packet reception, and transmits a determination response A5 including the determination result to the master station 1. Also good.

Returning to FIG. 4, the master station 1 executes a failure location identification process based on the determination responses A1 to A5 collected from the slave station 2 (step ST27).
The failure point identification process executed by the master station 1 includes a first identification process using the determination responses A1 to A4 and a second identification process using the determination response A5. FIG. 7A is a table summarizing the logic of the first specifying process, and FIG. 7B is a table summarizing the logic of the second specifying process.

As shown in FIG. 7A, in the first specifying process, the master station 1 caused the link breakage based on the combination of the determination results (normal or abnormal) of the slave station i and the slave station i + 1. Identify the fault location.
The master station 1 determines normal / abnormal (reception abnormality or transmission abnormality) of the slave station i based on the determination results included in the determination responses A1 and A2, and the determination results included in the determination responses A3 and A4 Based on this, the normal / abnormal (reception abnormality or transmission abnormality) of the slave station i + 1 is determined.

If the slave station i is abnormal and the slave station i + 1 is normal, the master station 1 determines that the slave station i is a single failure. As a result, it is found that the cause of the link disconnection was the reception abnormality or transmission abnormality of only the slave station i.
When the slave station i is normal and the slave station i + 1 is abnormal, the master station 1 determines that the slave station i + 1 has a single failure. As a result, it is found that the cause of the link disconnection was the reception abnormality or transmission abnormality of only the slave station i + 1.

When the slave station i is abnormal and the slave station i + 1 is abnormal, the master station 1 determines that the transmission path (link) is broken or that both slave stations i and i + 1 are at the same time.
The reason is that the transmission / reception of both slave stations i and i + 1 directly connected to the incommunicable link is not necessarily due to the damage of the transmission path. This is because a failure may occur.

When the slave station i is abnormal and the slave station i + 1 is abnormal, the master station 1 further executes a second specifying process described later.
When the slave station i is normal and the slave station i + 1 is normal, the master station 1 determines that the detection notification K notified from the slave station i is a false detection of link disconnection.

As shown in FIG. 7B, in the second specifying process, the master station 1 causes the occurrence of link disconnection based on whether the determination result of the transmission path included in the determination response A5 is normal or abnormal. Identify the fault location.
Specifically, when the determination result of the transmission path is normal, the master station 1 determines that the slave stations i and i + 1 are simultaneously failed, and when the determination result of the transmission path is abnormal, the master station i, It is determined that the transmission path between i + 1 is broken.

Returning to FIG. 4, the master station 1 generates one of the following final diagnosis results 1 to 4 based on the determination responses A1 to A5 collected from the slave station 2 and the first and second specifying processes. Any one of the generated diagnostic results 1 to 4 is transmitted to the central device 4 (step ST28).
As a result, the operator of the central device 4 can detect in advance the specific cause of the communication failure of the link that has occurred in the communication network NW.

Diagnosis result 1: Reception abnormality or transmission abnormality of only slave station i Diagnosis result 2: Reception abnormality or transmission abnormality of only slave station i + 1 Diagnosis result 3: Reception abnormality or transmission abnormality of both slave stations i and i + 1 Diagnosis result 4: Slave station i , I + 1 transmission line breakage

[Effect of this embodiment]
According to the slave station (communication device) 2 of the present embodiment, the control unit 30 performs both the first switching from the active operation to the passive operation and the second switching from the passive operation to the active operation. 21 can be forcibly executed.

  Therefore, for example, as shown in FIG. 1, the slave station 2 is employed as the communication node N of the communication network NW, and the slave stations i and i + 1 directly connected to the incommunicable link are forcibly passively operated to When i-1, i + 2 confirms communication (see FIGS. 3 to 6), the cause of the communication failure of the link can be determined. Therefore, it becomes possible to automatically diagnose the cause of the failure occurring in the communication network NW.

According to the slave station 2 of the present embodiment, when the count value of the timer 31 reaches a predetermined value (for example, a predetermined switching time notified from the master station 1), the control unit 30 switches from the passive operation to the active operation. The second switching is executed (see FIG. 5).
For this reason, the return means from the passive operation to the active operation can be easily implemented by the regular timer 31. That is, the slave station 2 can be manufactured at a lower cost than when a special circuit (see FIG. 8) such as the coupler 33 and the receiving unit 34 is used as a return means from the passive operation to the active operation.

According to the communication network NW of the present embodiment, both the first switching and the second switching are forcibly applied to the communication path in which four or more communication nodes N are arranged in series (the path of Ni-1 to Ni + 2 in FIG. 1). Executable slave stations 2 are included adjacent to each other.
For this reason, the slave stations i and i + 1 that are directly connected to the incommunicable link are forcibly passively operated and the other slave stations i-1 and i + 2 confirm the communication (see FIGS. 3 to 6). The cause of communication failure can be determined. Therefore, it becomes possible to automatically diagnose the cause of the failure occurring in the communication network NW.

  That is, in the present embodiment, among the four slave stations i-1, i, i + 1, i + 2, while at least one of the slave stations i, i + 1 is in passive operation, the other slave stations i-1, i + 2 communicate with each other. Since the confirmation is executed and the cause of the link communication failure is determined based on the result of the communication confirmation, the cause of the failure occurring in the communication network can be automatically diagnosed.

  More specifically, the slave station i and the slave station i + 2 perform the communication confirmation while the slave station i + 1 is in the passive operation, and based on the result of the communication confirmation, Is determined (see determination process Di in FIGS. 3 to 6). For this reason, it is possible to automatically diagnose a failure related to the slave station i.

  Further, the slave station i-1 and the slave station i + 1 perform communication confirmation while the slave station i is in passive operation, and based on the result of the communication confirmation, at least of the reception abnormality and transmission abnormality of the child station i + 1. One is determined (see determination process Di + 1 in FIGS. 4 to 6). For this reason, it is possible to automatically diagnose a failure related to the slave station i + 1.

  Furthermore, while the slave station i and the slave station i + 1 are in passive operation, the slave station i-1 and the slave station i + 2 execute the communication confirmation, and based on the result of the communication confirmation, the link (between the slave stations i and i + 1). Whether there is an abnormality in the transmission line) is determined (see determination process Dj in FIGS. 4 to 6). For this reason, it is possible to automatically diagnose a failure relating to a link such as a broken transmission line.

  In this respect, in the present embodiment, when communication failure is detected on a specific link, the central apparatus 4 acquires a communication frame including a diagnosis result of the cause of the failure. It is possible to immediately detect the location and the details of the failure. This facilitates maintenance management of the communication network NW.

[First Modification]
FIG. 8 is a block diagram showing a modification of the internal configuration of the slave station 2.
The slave station 2 according to the first modification shown in FIG. 8 is different from the slave station 2 (see FIG. 2) of the above-described embodiment as a means for second switching to return from passive operation to active operation. Instead of the timer 31, a coupler 33 and a receiving unit 34 are provided.

The coupler 33 is composed of an optical branching device that bifurcates an optical signal at N: 1 in both directions. The optical fiber of the bypass path 26 is connected to the port having the larger branching ratio, and the receiving unit is connected to the port having the smaller branching ratio. An optical fiber leading to 34 is connected.
For this reason, the optical signal passing through the bypass path 26 is branched with an intensity of 1 / N and input to the receiving unit 34. In order to prevent the light component of the bypass path 26 from being attenuated as much as possible, it is preferable to set N = 10.

The receiving unit 34 has a function of photoelectrically converting an input optical signal and a function of reproducing a communication frame from the converted electric signal, and can supply the reproduced communication frame to the control unit 30. .
For this reason, even if the optical switches 23 and 24 of the relay processing unit 21 are switched to the bypass path 26 (passive operation of the slave station 2), the control unit 30 can acquire a predetermined communication frame.

According to the slave station 2 of the first modification 1, since the control unit 30 can receive a communication frame even in the case of passive operation, the own station is activated from the passive operation based on the control signal received during the passive operation. It can be returned to operation.
For example, if the control unit 30 detects the end of the determination process by the other slave station 2 when transmission / reception of the Hello packet acquired from the bypass path 26 is completed during the passive operation, the control unit 30 returns to the active operation. Good. Alternatively, the active operation may be restored upon reception of a control frame that notifies the end of the determination process of the other slave station 2.

  As described above, if the control unit 30 can receive the communication frame from the optical signal passing through the bypass path 26, the slave station 2 becomes active from the passive operation in response to the end of the communication confirmation or the notification from the external device. Can return to operation.

[Second Modification]
FIG. 9 is a flowchart of another failure diagnosis process of the communication network NW that is executed in cooperation by the master station 1 and the plurality of slave stations 2.
The failure diagnosis process of FIG. 9 is a process when the communication network NW includes a slave station 2 that does not have a forced bypass function (for example, a slave station that cannot perform passive operation because it does not include the optical switches 23 and 24). .

Also in the second modification, it is assumed that communication failure (link disconnection) occurs on the transmission path between the slave station i and the slave station i + 1, and the slave station i detects this communication failure (see FIG. 1). ).
As shown in FIG. 9, in the communication between the slave station i and the slave station i + 1, when the slave station i detects a link break in one direction or both directions (step ST40), the slave station i notifies the detection of the link break. A detection notification is transmitted to the master station 1 (step ST41).

The detection notification includes identification information (such as a link number) of the transmission path that has become unable to communicate. The slave station i transmits a detection notification in a direction not including the transmission path in which the link breakage occurs (counterclockwise in the example of FIG. 1).
When the master station 1 receives the detection notification, the master station 1 identifies the link from which the link break has been detected from the identification information included in the detection notification, and determines the failure to address the two slave stations i and i + 1 directly connected to the link. A determination request for requesting is transmitted (step ST42).

That is, the communication node N set as the transmission destination of the determination request is one communication node (slave station i) and the other communication node (slave station i + 1) that are directly connected to the incommunicable link.
The master station 1 transmits a determination request in a direction that does not include the transmission path in which the link break has occurred. Specifically, the master station 1 transmits a determination request addressed to the slave station i in the clockwise direction, and transmits a determination request addressed to the slave station i + 1 in the counterclockwise direction.

Next, the slave station i that has received the determination request checks the light emission of the optical transceivers 27 and 28 of the local station (step ST43). That is, the slave station i determines whether or not the optical transceivers 27 and 28 of its own station are emitting light (step ST44).
If the determination in step ST44 is affirmative, the slave station i generates a determination result that the own station is out of order (step ST45), and if the determination in step ST44 is negative, the slave station i A determination result indicating that the own station is normal is generated (step ST46).

Next, the slave station i + 1 that has received the determination request checks the light emission of the optical transceivers 27 and 28 of its own station (step ST47). That is, the slave station i + 1 determines whether or not the optical transceivers 27 and 28 of its own station are emitting light (step ST48).
If the determination in step ST48 is affirmative, the slave station i + 1 generates a determination result indicating that the own station is out of order (step ST49), and if the determination in step ST48 is negative, the slave station i +. Generates a determination result indicating that the own station is normal (step ST50).

When the determination result is obtained, each of the slave stations i and i + 1 returns the content of the failure diagnosis to the master station 1 (step ST51). Specifically, each of the slave stations i and i + 1 generates a determination response including the determination result, and transmits the generated determination response to the master station 1.
Thereafter, the master station 1 notifies the central device 4 of the failure content by transmitting a communication frame including the content of the determination result received from each of the slave stations i and i + 1 to the central device 4 (step ST52).

  According to the second modified example, the failure diagnosis accuracy in the communication network NW is inferior, such as failure of the transmission path cannot be diagnosed, but even when the communication node N that cannot perform passive operation is included in the communication network NW. Which communication node N has failed can be diagnosed.

[Other variations]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

For example, in the above-described embodiment, the slave station 2 executes the determination processes Di, Di + 1, Dj (FIG. 6), but this determination process may be executed by the master station 1.
In this case, each slave station 2 notifies only the success / failure of the communication confirmation (specifically, the success / failure of the reception of the Hello packet) to the master station 1, and based on the notified success / failure of the communication confirmation, The determination processes Di, Di + 1, Dj shown in FIG.

In the above-described embodiment, the central apparatus 4 may execute the failure diagnosis process performed by the master station 1 instead.
In this case, the central device 4 may execute both of the determination processes Di, Di + 1, Dj in FIG. 6 and the specific process in FIG. 7, or the determination processes Di, Di + 1 in FIG. 6 as in the above-described embodiment. , Dj may be executed by the slave station 2 and the specific processing of FIG.

  In the above-described embodiment, the master station 1 supervises the fault diagnosis processing related to the communication network NW, but one of the plurality of slave stations 2 included in the communication network NW (for example, the slave station i-1) is faulty. The diagnosis process may be integrated and the final diagnosis result may be notified to the master station 1 and the central device 4.

1 Master station (communication device)
2 Slave station (communication equipment)
DESCRIPTION OF SYMBOLS 3 Transmission path 4 Central apparatus 5 Distribution line 6 High voltage switch 11 Relay processing part 12 Power supply part 13 Control part 21 Relay processing part 22 Power supply part 23 Optical switch 24 Optical switch 25 Normal path 26 Bypass path 27 Optical interface 28 Optical interface 29 Relay Unit 30 Control unit 31 Timer 33 Coupler 34 Receiver NW communication network N Communication node P1 Communication side port P2 Bypass side port

Claims (8)

A communication device used in a communication network adopting a bucket relay system,
A relay processing unit capable of a passive operation that allows a signal that has reached its own station to pass without amplification, and an active operation that amplifies and relays the signal that has reached its own station;
A control unit capable of forcibly executing both the first switching from the active operation to the passive operation and the second switching from the passive operation to the active operation with respect to the relay processing unit; Communication device. It further includes a timer that locally measures the time lapse of its own station,
The communication device according to claim 1, wherein the control unit executes the second switching when a count value of the timer reaches a predetermined value. A receiving unit capable of receiving a control signal from the outside during the passive operation of the relay processing unit;
The communication device according to claim 1, wherein the control unit performs the second switching based on the control signal received by the receiving unit. A communication network having a communication path in which four or more communication nodes communicating in a bucket relay system are arranged in series,
In the communication path, communication capable of forcibly executing both the first switching from the active operation defined below to the passive operation defined below and the second switching from the passive operation to the active operation. A communication network including communication nodes adjacent to each other as a device.
Active operation: Operation to amplify and relay the signal that has reached its own station Passive operation: Operation to pass the signal that has reached its own station without amplification A communication network failure diagnosis method according to claim 4,
A first step of detecting communication failure of one link included in the communication path;
Of the first to fourth nodes defined below, while at least one of the second and third nodes is in the passive operation, a second step in which another communication node performs communication confirmation;
And a third step of determining a cause of communication failure of the link based on a result of confirmation of communication of the other communication node.
First node: A communication node adjacent to the second node and not directly connected to the incommunicable link Second node: One communication node directly connected to the incommunicable link Third node: Directly connected to the incommunicable link The other communication node Fourth node: a communication node that is adjacent to the third node and is not directly connected to an incommunicable link The second step includes a process in which the second node and the fourth node perform communication confirmation while the third node is in the passive operation.
The third step includes a process of determining at least one of reception abnormality and transmission abnormality of the second node based on a result of communication confirmation between the second node and the fourth node. The communication network failure diagnosis method according to claim 5. The second step includes a process in which the first node and the third node execute communication confirmation while the second node is in the passive operation.
The third step includes a process of determining at least one of reception abnormality and transmission abnormality of the third node based on a result of communication confirmation between the first node and the third node. The communication network failure diagnosis method according to claim 5 or 6. The second step includes a process in which the first node and the fourth node perform communication confirmation while the second node and the third node are in the passive operation,
8. The process according to claim 5, wherein the third step includes a process of determining whether or not there is an abnormality in the link based on a communication confirmation result between the first node and the fourth node. The communication network failure diagnosis method according to claim 1.

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