JPS634733A - Fault detecting and eliminating method for optical communication system - Google Patents

Abstract

PURPOSE:To surely execute the discrimination whether or not its own station node is faulty by stopping power supply to an electrooptic conversion block for a period different from each node if a fault signal takes place consecutively in an optical transmission line so as to keep the transmission signal output of all nodes at a no signal until the fault detection for all the nodes is finished. CONSTITUTION:In detecting the occurrence of a fault signal in an optical transmission line 4 consecutively for the 1st prescribed time T0, a control section 10 stops the power supply to the elecrooptic conversion block 12b for the 2nd prescribed time Ti specific to the said node and keeps the transmission signal output at no signal while supervising the signal state of the line 4 and restarts the power suply to the block 12b. Then the section 10 discriminates the presence of the occurrence of the faulty signal in the line 4 just after the restart to execute the fault detection of the said node and restarts the transmission output after the 3rd prescribed time T1 sufficient for the compression of the fault detection to all the other nodes N1-Nn while the transmission signal output is kept to no signal if the fault of the said node is not detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fault detection and removal method for an optical communication system in which a plurality of nodes are connected by an optical transmission path having a star coupler.

(Prior Art and its Problems) Conventionally, a star type optical communication system is known in which a plurality of nodes are connected by, for example, an optical transmission path having a pensive star coupler, and data is exchanged between the nodes. Fifth
The figure shows the overall configuration of a conventional optical communication system, in which a plurality of nodes 1.2a to 2C are connected to each other by an optical transmission line 4 via a puffy star coupler 3. In the conventional optical communication system, a specific node l among these plurality of nodes 1, 2a to 2C acts as a monitoring station, constantly monitors the signal state of the optical transmission line 4, shuts off the power of a failed node, and maintains the network. By removing the failed node from the network, a situation where the entire system becomes unable to communicate is avoided. More specifically, as shown in FIG. 6, the monitoring station node 1 includes a central control unit 10 that controls specific control of the node 1, a communication control unit 11 that controls data communication between nodes, An optical/electrical conversion block 12a is connected to an optical transmission line 4 made of an optical fiber cable and converts an optical signal input from the optical transmission line into an electrical signal, and an optical/electrical conversion block 12a converts an electrical signal from the communication control unit 11 into an optical signal. It is composed of an optical transmitting/receiving section 12 consisting of an electrical/optical conversion block 12b that outputs a transmission signal to another node to the optical transmission line 4, a power source 13, and a power switch 14 whose operation is controlled by the central control section IO. , central control unit 1
0, the optical/electrical conversion block 12a of the communication control unit 11 and the optical transceiver 12 is supplied with power from the electric rA 13 directly via the power supply line 15, and the optical/electrical conversion block 1 of the optical transceiver 12 is
2b is the power supply line 16 and the power switch 14 from the electric tA13
Powered via.

On the other hand, the other nodes 2a to 2c, as shown in FIG.
A central control unit 10° that controls the unique control of each node 2a (2b, 2c), a communication control unit 11' that controls data communication between nodes, and a central control unit 11' that is connected to the optical transmission line 4,
The sixth section performs electrical-to-optical conversion and optical-to-electrical conversion of transmission signals.
It is composed of an optical transmitter/receiver 12° similar to the optical transmitter/receiver 12 shown in the figure, a power supply 13', and a power switch 14°, and the central control unit 10' is directly supplied with power from the power supply 13° via a power supply line 15°. The communication control section 11' and the optical transmitting/receiving section 12' are supplied with power via a power switch 14' and a power supply line 16'. The power switch 14° of each node 2a (2b, 2c) is connected to the power switch control line 5a (5b, 5
c) are respectively connected to the output side of the central control unit 10 of the monitoring station node 1, and their operation is controlled by the central control unit 10 of the monitoring station node 1.

The central control unit IO of the monitoring station node 1 constantly monitors the signal state of the optical transmission line 4 that is input via the optical-to-electrical conversion block 12a of the optical transmitting and receiving unit 12 and the communication control unit 11,
If it is determined that the optical transmission line 4 is filled with abnormal signals such as continuous light or irregular light emission that cannot be synchronized, and communication between nodes is not possible, the central control unit 1O switches the Ti source switch control lines 5a to 5C and 18, and sequentially cut off the power supply to each communication control unit 11'' and optical transmitting/receiving unit 12° of nodes 2a to 2c other than the monitoring station node 1 for a certain period of time, the own station Electricity of the optical transmitter/receiver 12
The power supply to the optical conversion block 12b is also interrupted for a certain period of time. If there is no abnormality in the signal state of the optical transmission line 4 while the power supply was cut off, the node that cut off the power supply is recognized as the faulty node, and the power supply to the node is maintained in a stopped state. The faulty node is removed from the system, the abnormal signal is removed from the optical transmission line 4, and the system is returned to a communicable state.

In such a conventional optical communication system, in addition to the power switch 14, 14' provided at each node, there is also a power switch system between the monitoring station node and other nodes. There is a problem in that it is necessary to wire the lIl cottons 5a to 5C.

FIG. 8 shows another conventionally known optical communication system.
The node configuration shown in the figure is similar to that in FIG. 7, but differs from that in FIG. 7 in that each node is provided with an abnormality detection circuit 18. That is, in the optical communication system shown in FIG.
The operation of the power switch 14' is controlled by an abnormality detection circuit 18 provided in each node. Monitor abnormalities such as continuous light emission of the block, and if an abnormality occurs in the electrical/optical conversion block of the local station, switch the power switch 14° of the local station and activate the communication control unit 11' of the local station and optical transmission/reception. By stopping the power supply to the section 12', each node detects the abnormality by itself and leaves the system when the abnormality occurs.

This optical communication system does not require power switch control lines wired between the monitoring station node and other nodes like the systems shown in Figures 5 to 7, but each node has its own electrical/optical converter. An abnormality detection circuit that constantly monitors the operating status of the block, detects an abnormal signal in the optical transmission line, and turns off the power of its own station is required.If such an abnormality detection circuit is provided at each node, the system The problem is that it becomes expensive.

The present invention has been made to solve such problems, and is intended to improve continuous light emission and synchronization of electrical-to-optical conversion blocks in an optical communication system in which multiple nodes are connected by an optical transmission path having a puffy star coupler. Fault detection and detection for optical communication systems that can inexpensively and reliably prevent the entire system from becoming unable to communicate due to abnormal signals such as irregular light emission that cannot be detected.
The purpose is to provide a removal method.

(Means for Solving the Problems) According to the present invention, in order to achieve the above-mentioned object, each node of a plurality of nodes connected to an optical transmission line having a star coupler is unique to the current node. ; a central control unit that controls ν control, a communication control unit that controls data communication between nodes, an optical-to-electrical conversion block that converts optical signals input from the optical transmission line into electrical signals, and In a method for detecting and removing a fault in an optical communication system comprising an optical transmitting/receiving unit consisting of an electrical/optical conversion block that converts the signal to be transmitted to another node and outputs the signal to be transmitted to another node onto an optical transmission path, each node is provided with the optical A first power supply route that supplies power to the electrical conversion block, a second power supply route that supplies power to the electrical/optical conversion block, and one of the central control unit and the communication control unit in the middle of the second power supply route. switch means that are switched and controlled by a control section, and when the one control section of each node detects that an abnormal signal has continuously occurred in the optical transmission path for a first predetermined period of time, After switching and operating the switch means to stop power supply to the electrical/optical conversion block for a second predetermined time specific to the node,
While monitoring the signal state of the optical transmission line via the optical-to-electrical conversion block of the node, and by keeping the transmission signal output at no signal, restarting the power supply to the electric-to-optical conversion block, and restarting the power supply. Immediately after restarting, it determines whether or not an abnormal signal has occurred in the optical transmission path to detect a failure in the node, and if no failure is detected in the node, the transmission signal output is maintained at no signal and other nodes are detected. After waiting for the elapse of a third predetermined time period that is sufficient to complete failure detection of all nodes, output of the transmission signal is resumed, and if a failure of the node is detected, the transmission signal is transmitted to the electrical-to-optical conversion block. Provided is a method for detecting and removing a fault in an optical communication system, which comprises stopping the power supply to the electrical-to-optical conversion block again and thereafter maintaining the power supply stopped state to the electrical-to-optical conversion block.

(Function) The control unit of either the central control unit or the communication control unit of each node constantly monitors the state of the optical signal input from the optical transmission path via the optical/electrical conversion block of the optical transmitter/receiver, and transmits the optical signal. When it is detected that an abnormal signal such as continuous light or irregular light that cannot be synchronized has occurred continuously for a first predetermined period of time, a unique signal that is preset to a different value for each node is detected. By stopping the power supply to the electric/optical conversion block for a predetermined period of time in step 2, and then detecting the failure of the own node, the third
By keeping the transmitted signal output at no signal until the predetermined time period has elapsed, it is possible to reliably determine whether or not the own node is abnormal without misdiagnosing it. When an abnormality is detected in the local node, the power supply to the optical-to-electrical conversion block of the optical transmitter/receiver of the local node is maintained in a stopped state, and the node leaves the system, and is executed in this way by one of the control units. By detecting and removing system failures through software using a failure detection/removal program, it is possible to inexpensively and reliably avoid communication failures in the entire system without the need for a separate special abnormality detection circuit. Make it.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

First, FIG. 2 shows the connection relationship of each node of an optical communication system implementing the method of the present invention, from the first node N1 to the nth node.
n nodes are connected radially through passive star couplers 3 by optical transmission lines 4 up to node Nn.

In an optical communication system implementing the method of the present invention, each node is basically configured as shown in FIG. 3 without using a specific node as a monitoring station node. The node configuration shown in FIG. 3 is similar to the node configuration shown in FIG. 6 described above, except that the power switch control line 18 from the output side of the central control unit 1O is connected only to the power switch 14 of the local station. The only difference is that the other components are the same as those in FIG. 6, so the same reference numerals are given to the components corresponding to those in FIG. 6, and detailed explanation thereof will be omitted.

Next, referring to FIG. 1 and FIG. 4, each node N1 to Nn
Describes the fault detection and removal procedures carried out by The central control unit 10 of each node N1 to Nn monitors the signal state of the optical transmission line 4 via the optical/electrical conversion block 12a of the optical transmission/reception unit 12 and the communication control unit 11. An abnormal signal such as light or irregular light emission that cannot be synchronized is generated, and it is determined whether or not a failure has occurred in which this abnormal signal occupies the optical transmission line 4 and disables communication between nodes (step 20). If one of the nodes constituting the optical communication system (for example, assume that node N2 has failed) fails and outputs continuous light to the optical transmission line 4, each node will receive an abnormal signal. It is determined whether a failure has occurred in the optical transmission line 4 based on whether a certain continuous light continues for a first predetermined time To or more. If the determination in step 20 is affirmative (Yes), that is, if continuous light continues to occur in the optical transmission line 4 for a first predetermined time period of 10 or more, the central control unit 10 interrupts communication with other nodes. That is, while making the transmission signal output non-signal, a switching signal is output to the power switch 14 via the power switch control line 18 to turn off the power switch 4, and the electrical/optical conversion block of the optical transmitter/receiver 12 is turned off. Stop power supply to 12b (step 21)
.

Since each of the nodes N1 to Nn executes failure detection according to the procedure of the flowchart shown in FIG. Since the power supply to the electrical/optical conversion block of the station is stopped, taking into consideration differences in program execution timing, etc., at least a predetermined period of time after the elapse of the predetermined time To from the time when the abnormal signal is generated (time p1 in FIG. 4). Within to (
Within time 92 in FIG. 4), all nodes N1 to Nn will complete stopping the power supply to the electrical-to-optical conversion block, and at the latest at time 92, there will be no optical signal in the optical transmission line 4. , there will be no signal (see Figure 4).

Next, it is determined whether or not a unique time (second predetermined time) τi assigned in advance to the own station has elapsed since the time when the power supply to the own station was stopped (step 22), and if it has not elapsed, the time elapses. Step 22 is repeatedly executed until the predetermined time τi elapses. Here, τi is a predetermined time specific to the first node Ni, and its value is set by the following equation.

τi x (tl + t3 + t5) and tl is an appropriate predetermined value larger than the predetermined time 10 (tl >
to), and t3. t5 is also a predetermined time t2, which will be described later.
Appropriate predetermined values each larger than t4 (t3>t2.15
>t4).

If the determination result in step 22 is affirmative, that is, if a predetermined time τi specific to the own station has elapsed, the central control unit 10 switches the power switch control line 1 while leaving the transmission signal output as no signal.
8 to turn on the power switch 14, thereby restarting power supply to the electrical/optical conversion block 12b (step 23).

Then, for a predetermined time t, the optical/electrical conversion block 12a
The signal state of the optical transmission line 4 is monitored over two periods, and it is determined whether or not an abnormal signal has occurred on the optical transmission line 4 within the subsequent predetermined time t4 (step 24). This value is set to a value sufficient to be able to reliably determine whether or not an abnormal signal has occurred in the optical transmission line 4 without misdiagnosing it.

If the determination result in step 24 is negative (No), it means that there is no abnormality in the electric/optical conversion block 12b, etc. of the local node, and it is determined that the cause of the failure in the optical transmission line 4 is not in the local node. , executes the steps after step 25, which will be described later, while supplying power to the electric/optical conversion block 12b of its own node. In this case, the optical transmission line 4 will be maintained in a no-signal state.

On the other hand, when the faulty node N2 executes step 23, the abnormality signal S2 appears again on the optical transmission line 4 (at time 93 of fal in FIG. 4), and the determination result in step 24 becomes affirmative. In this case, the central control unit 10 of the node N2 turns off the power switch 14 within a predetermined time t4 following the predetermined time t2 to again stop the power supply to the electric/optical conversion block 12b, and fixes this state. , remove your station from the system. Electrical/optical conversion professional for failure node N2.

When the power supply to the optical transmission line 12b is stopped, the fault signal is removed from the optical transmission line 4 (at time 94 in fat in Figure 4), and the optical transmission line 4
becomes no signal again.

After making the determination in step 24, the other node with no abnormality determines whether or not the third predetermined time TI has elapsed from the time when the own node detected the occurrence of the fault signal in the optical transmission line 4 (step 25). , waits for the elapse of a predetermined time Tl (point 25 in Figure 4 (al)), and resumes communication with other nodes (
Step 26). Failure detection for all nodes should be completed by the time (n+1) x (tl+t3+t5) has elapsed at the latest, and the predetermined time TI is equal to this time (
n+1)x (H+t3+t5) is set to an appropriate predetermined value. Incidentally, t3 and t5 are the same as those in step 24.
Since the predetermined times t2 and [4 explained in 27 are set to an appropriate predetermined value, two or more This avoids a situation in which the nodes execute step 23 at the same time and start supplying power to each electrical/optical conversion block 12b, and as a result, each node sequentially detects a fault in its own node starting from the first node N1, and This means that it can be executed reliably without conflicting with node failure detection.

In the above embodiment, the power switch I4 is connected to the central control unit l.
power switch 14 by the central control unit 10.
Although the present invention is not limited to this, the signal control unit 1 is used instead of the central control unit IO.
1 to execute a control program necessary for fault detection and removal shown in the 11N flowchart, and the signal control unit 11 may control the operation of the power switch 14.

Further, in the above embodiment, only the electrical/optical switching block 12b of the optical transmitter/receiver 12 was controlled on/off by the power switch 14, but the optical/electrical switching block 12a is also supplied with power via the power switch 14. , the power supply to the electrical/optical exchange block 12b and the optical/electrical exchange block 12a may be controlled to be turned on and off simultaneously.

(Effects of the Invention) As described in detail above, according to the method for detecting and removing a fault in an optical communication system of the present invention, each node has a first power supply route that supplies power to an optical-to-electric conversion block, and a first power supply path for supplying power to an optical-to-electrical conversion block. A second power supply route for supplying power to the blocks, and a switching means that is switched and controlled by one of the central control unit and the communication control unit are provided in the middle of the second power supply route, and each node The control unit detects the first abnormal signal in the optical transmission path.
When it is detected that this has occurred continuously for a predetermined period of time, the switching means is activated to stop the power supply to the electrical/optical conversion block for a second predetermined period specific to the node, and then the optical/optical conversion block of the node is switched on and activated. While monitoring the signal state of the optical transmission line via the electrical conversion block and keeping the transmission signal output at no signal, power supply to the electrical/optical conversion block is resumed, and immediately after the power supply is resumed, the optical transmission line is restarted. detects the occurrence of an abnormal signal in the node, detects the failure of the node, and
If a failure of the node is not detected, the transmission signal output is held at no signal and the transmission signal is output after waiting for a third predetermined time period that is sufficient to complete the failure detection of all other nodes. If a failure in the relevant node is detected, the power supply to the electrical/optical conversion block is stopped again, and the power supply to the electrical/optical conversion block is maintained in the stopped state. tif! Wiring between a monitoring station and other nodes when an optical transmission path is monitored by a specific monitoring station node! In addition to eliminating the need for an X-switch control line, system failures are detected and removed by software by executing the abnormality detection and removal program by one of the control sections, so there is no need to provide a special abnormality detection circuit. This has the excellent effect of being able to reliably and inexpensively avoid a situation where the entire system becomes unable to communicate due to a failed node.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a flowchart showing a procedure for detecting and removing a fault in an optical communication system according to the method of the present invention, and FIG.
An overall configuration diagram of an optical communication system in which multiple nodes are connected by an optical transmission line having a star coupler. Figure 3 is a circuit diagram showing the internal configuration of each node shown in Figure 2. Figure 4 is a diagram of the optical transmission line. Timing chart showing time changes in signal states and on/off states of the electrical/optical conversion blocks of each node, No. 5
Figures 8 through 8 are explanatory diagrams of conventional optical communication systems.
Figure 6 shows the overall configuration of a conventional star-type optical communication system.
The figure is a circuit diagram showing the internal configuration of the monitoring station node l in FIG.
FIG. 7 is a circuit diagram showing the internal configuration of nodes other than the monitoring station node in FIG. FIG. 2 is a circuit diagram showing the configuration. 3... Passive star coupler, 4... Optical transmission line, 1
0... Central control unit, 11... Communication control unit, 12...
・Optical transmitter/receiver unit, 12a...optical/electrical conversion block, 1
2b... Electricity/light conversion block, 13... Power supply, 1
4... is switch, 15... power supply line (first power supply route), 16... power supply line (second power supply route), 18.
...Power switch control line, N1~In...Node.

Claims (1)

[Claims] Each node of a plurality of nodes connected to an optical transmission line having a star coupler includes a central control unit that controls specific control of the node, a communication control unit that controls data communication between nodes, and the optical transmission line. An optical/electrical conversion block that converts the optical signal input from
In a fault detection/removal method for an optical communication system including an optical transmitter/receiver section including an optical conversion block, each node has a first power feeding path for feeding power to the optical/electrical conversion block, and a first power feeding path for feeding power to the optical/electrical conversion block, and A second power supply route for supplying power and a switch means that is switched and controlled by one of the central control unit and the communication control unit are provided in the middle of the second power supply route, and each node When the control unit detects that an abnormal signal has continuously occurred in the optical transmission path for a first predetermined period of time, the control unit switches and operates the switch means to supply power to the electrical-to-optical conversion block to the node. After stopping for a unique second predetermined period of time, the electrical/optical signal is switched on while monitoring the signal state of the optical transmission line via the optical/electrical conversion block of the node and keeping the transmission signal output at no signal. restarting power supply to the conversion block, and immediately after restarting the power supply, detecting a failure of the node by determining whether an abnormal signal has occurred in the optical transmission path;
If a failure of the node is not detected, the transmission signal output is held at no signal and the transmission signal is output after waiting for a third predetermined time period that is sufficient to complete failure detection of all other nodes. , and if a failure of the node is detected, the power supply to the electrical/optical conversion block is stopped again, and the power supply stopped state of the electrical/optical conversion block is maintained thereafter. How to detect and remove system failures.