JPH10145381A - Communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system, where a master station can always control/manage its slave stations with no interruption of the system operation, even when the faults occur or the slave stations are added. SOLUTION: A master station 11 is connected to its slave stations 12 or the stations 12 are connected to each other, via channels 14 set opposite to each other. Thus, a double-loop, structure is obtained. In a normal state, a control/management communication virtual path of a working system is set at only the single side of a loop between the stations 11 and 12 by means of the channels 14 of the double-loop structure. On the other hand, a control/ management communication virtual path of a standby system is set at the other side of the loop in a state, where the virtual path is cut at its middle part. If a fault occurs and the virtual path of the working system is cut, the station 11 or 12 sets the cut part of the path of the working system to complete a virtual path of the standby system. Thus, the control/management communication is restored between the stations 11 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data processing center for centrally managing and controlling data sources and data receiving devices and data receiving devices when the data generating sources or data receiving devices are arranged in a loop. And a communication system constituted by a communication network connecting

[0002]

BACKGROUND OF THE INVENTION The present invention relates to a communication device used in a communication system connecting a data processing center and a data generation source when a data generation source or a data reception device is arranged in a loop. Representative examples of communication systems in which data sources are arranged in a loop include a road management system, a railway management system, a sewer management system, an airport management system, a river management system, a subway management system, and the like.

In a road management system, a management center exists in a management section. In the management section, a video camera, an emergency telephone, a vehicle body sensor, and the like are arranged along a road, and information from the center is collected by the management center. Have been. In addition, electronic bulletin boards are also arranged along the road. The management center also collects information on accidents and traffic jams from adjacent management sections, and makes various decisions using such information and the information on the management sections. As a result, various types of guidance including traffic jam information are provided. It is displayed on the lightning board and traffic management is performed.

[0004] Such a road management system can be constructed, for example, with devices and transmission lines as shown in FIG.
In the figure, reference numeral 12 denotes a node device (hereinafter, referred to as a slave station) used as the above-mentioned management center, and reference numeral 13 denotes a local communication device corresponding to a video camera, an emergency telephone, a vehicle body sensor, an electric bulletin board, and the like in the management section. And
Reference numeral 11 denotes a center device (hereinafter, referred to as a master station) that manages the slave station 12 and the local communication device 13. Reference numeral 14 denotes an optical cable as a transmission line, which transmits the master station 11 to the start end, receives the slave station 12, and transmits the slave station 12 to the downstream slave station or the master station 11, that is, a loop for transmitting in one direction. It has a circuit shape.

[0005] Such a system configuration is called ATM (Asynchro
nous Transfer Mode: When configured with the function of an exchange switch, information transmitted from the local communication device 13-1 to the master station 11 or another local communication device 13-2 (for example, a traffic jam situation image image by a video camera, A telephone provided on the route, etc), information transmitted from another local communication device 13-3 to the local communication device 13-4, control management information between the master station 11 and each slave station 12, and the like are transmitted through a transmission line. The information can be transmitted and received on the same 14 networks, and one information content can be transmitted to many destinations according to the content of a cell (Cell).

In the above operation management, if a system error occurs, the system operation becomes impossible. For example,
If an abnormality occurs in a certain one of the slave stations 12 or an optical cable and a fault occurs due to disconnection or a fault, the loop is a one-way loop. Therefore, the information of the faulty slave station 12 and the information of the local communication device 13 are provided. The master station 11 could not acquire all the information, and the system operation was stopped. In addition, even if repairs are made, it is not possible to detect in which area the abnormality has occurred, and the system must be traced from the beginning to investigate. Then
Such a situation could lead to panic. In addition, when adding or reducing the slave stations 12, it is necessary to stop the system.

[0007]

As described above, in the conventional loop communication system, for example, if a failure occurs in the optical cable connecting the n-th slave station or the (n-1) -th and n-th slave stations, The information from the master station can be transmitted to the (n-1) th slave station, but the information of each slave station cannot be returned to the master station, and the system function must be stopped. As described above, there has been a problem that the system function is stopped during the repair.

In addition, there is a problem that the system function must be stopped at the time of inspection and expansion / reduction of the slave station, and there is a lack of flexibility in changing the configuration of the system.

As a countermeasure for this, there has conventionally been a loop LAN having a double loop configuration. However, most of the LANs are duplicated with only the optical cable of the transmission line, and failure information is provided because the physical part is single. There was no flexibility in detecting and notifying. Further, a dedicated circuit for switching is required, and there is no commonality with the branch / insert function of the station.

The present invention eliminates the above-mentioned problems. In this type of loop network, when a failure occurs or when the number of slave stations is increased / reduced, the system is reconfigured, and the master station constantly controls and manages the slave stations. It is an object of the present invention to provide a communication system capable of performing the communication.

[0011]

SUMMARY OF THE INVENTION The present invention provides a plurality of node devices distributed at a plurality of locations, one or more local communication devices connected to each of the node devices, A center device for controlling and managing the local communication device, and opposed communication path means for serially connecting the node devices and between the center device and the node device, wherein the center device and the node device have the communication path means. It has two circuits to be accommodated, arranges and connects the center device and the node device in a double loop, and performs communication between the devices by cell data, wherein the node device is the center device Has a control management function of performing communication control with the own station, and according to the destination of the cell, the cell from the local communication device connected to the own station. A cell for control and management of a station and a cell received from the center device or another node device are mixed without overlapping and transmitted to the center device or another node device, or the center device or another node device And a cell switch means for transmitting a cell received from the local station to a control management function of the local station or a local communication apparatus connected to the local station, and the center apparatus controls and manages the node apparatus by communicating with the node apparatus. And has a system management function to control and manage the own station.
According to the destination of the cell, the cell for control management and the cell received from the node device are mixed and transmitted to another node device without overlapping, or the cell received from the node device is transmitted to the system management function of the own station. In a communication system including a cell switch unit for transmitting, when a failure occurs in the communication path unit and each of the node devices or when the number of the node devices is increased / reduced, the communication between the center device and the node devices in the loop network is performed. The center device constantly controls and manages each of the node devices by using a route in which a fault has occurred or a route opposite to the route on the increase / decrease side among the routes. It is characterized by being able to do.

Also, in the present invention, the center device and the node device use the cell switch means, and when a failure occurs, the center device and the node device change the path setting of the cell switch means, so that the center device and the node device can be connected to each other. A path used for control management communication between node devices is switched.

Further, in the present invention, the center device and the node device are provided with a function of detecting a failure of the communication path means in the physical layer termination circuit. To notify the center device of the occurrence of a failure, and automatically recover the control management communication function between the center device and the node device.

Further, in the present invention, the center device confirms the existence of the node device at regular time intervals, monitors the normal state of the network by receiving a response from the node device, In this case, a failure is detected by not receiving a response to the existence confirmation of the failure, and a failure location is detected.

Further, in the present invention, the center device, the node device, and the communication path means are realized by an ATM (asynchronous transfer mode) switching function.

In the present invention, a virtual path for normal control management communication is set between the center device and the node device on only one side of the loop, and a spare control management communication is established from the other side of the loop. Virtual path for the intermediate route 1
When the virtual path for control communication at normal time is broken due to a failure or when the virtual path for control communication at normal time is increased or decreased due to the increase / decrease of the node devices, the virtual path for control communication at normal time is set. When the center device or the node device disconnects, the interrupted portion of the backup virtual path is set and the backup virtual path is completed, whereby the control management between the center device and the node device is completed. It is characterized in that communication can always be performed.

Also, in the present invention, virtual paths for control management communication are set between the center device and the node device on both sides of the loop, and when one of the virtual paths is broken due to a failure, or When the number of node devices is increased / decreased, control management communication between the center device and the node devices can be always performed by using one virtual path.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A communication system according to the present invention includes a plurality of node devices (hereinafter, referred to as slave stations) distributed at a plurality of locations and one or more local communication devices connected to each of the slave stations. And a center device (hereinafter, referred to as a master station) for controlling and managing the slave station and the local communication device, and opposing communication path means for connecting the slave station and the master station in series. Is provided with two circuits for accommodating
The slave station and the master station are connected in a double loop, and communication between the devices is performed by cell data.

The slave station has a control management function of communicating with the master station and performing control management of the own station. According to the destination of the cell, the slave station controls the cell from the local communication device connected to the own station and the control management of the own station. The cell received from the master station or another slave station is mixed with the cell received from the master station or another slave station without overlapping, and the cell received from the master station or another slave station is sent to the own station. And a cell switch for transmitting to a local communication device connected to the own station.

Similarly, the master station has a system management function of communicating with the slave station and performing control management of the slave station, and has a system management function of performing control management of its own station. A cell switch is provided for transmitting cells received from the child station to the child station without being overlapped, and for transmitting cells received from the child station to the system management function of the own station.

The master station and the slave stations are provided with a transmitter, a receiver, and LOS / LOF (Loss Of Signal: Loss Of Signal).
Flame: Loss of frame detection) LOS
A physical layer terminator having a function of transmitting a far-end reception error to the opposite side when / LOF is detected is provided.

When the slave station detects a transmission path failure such as LOS / LOF or far-end reception error, it automatically switches its own switch and uses a transmission path free from failure. And notifies the master station of the failure. For failures that cannot be detected by the slave station, the master station periodically checks the survival of each slave station using the working transmission line, and the response from each slave station is sent from the standby transmission line. It confirms that there is no failure by being transmitted, and detects failure by not being transmitted. In addition, the master station has a function of performing switching control of the switches of the master station and the slave station when a failure occurs, and restoring the communication function with the slave station.

The master station, slave stations and communication path means are realized by an ATM switching function, and
It is composed of double loops, and communication for control management between the master station and each slave station is performed in two directions. In this case, a virtual path for active control management communication is set between the master station and the slave station on only one side of the loop, and a virtual path for standby control management communication is set from the other side of the loop. The setting is made in a state where only one part of the route is interrupted. When a fault occurs and the virtual path for the control communication of the active system is cut off, the master station or the slave station sets the interrupted portion of the virtual path of the standby system to complete the virtual path of the standby system. Thus, control management communication between the master station and the slave station can be restored.

When the slave station detects a failure in the communication path,
The master station is notified of the occurrence of the failure, but if the active control virtual path is interrupted due to the failure, the slave station sets the switch and completes the standby control management virtual path, and the master The control management communication is restored.

A failure that cannot be detected by the slave station (such as a failure of the slave station itself) is detected by confirming the existence of the master station. The master station regularly checks the existence of each slave station by using the control path of the active system, confirms that the slave station is normal by receiving a survival confirmation response from the slave station, and does not receive a response. At times, it is determined that a fault has occurred in the slave station itself or in the slave station and a slave station upstream of the slave station. At that time, the master station sets the cell switch of the master station and the cell switch of the slave station with respect to the slave stations downstream of the failure location and the slave station, and completes the virtual path for control and management of the standby system.
Perform control management communication.

A virtual path for control management communication is set between the master station and the slave station from both sides of the loop. Even if one of the control management virtual paths is broken due to a failure, control management communication is performed using the other control management virtual path. Thus, even when a failure occurs, the master station can easily restore the control management communication with each slave station.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a communication system according to an embodiment of the present invention. In this communication system, a system management center (hereinafter, referred to as a master station) 11 that performs operation management of the entire system, a plurality of node devices (hereinafter, referred to as slave stations) 12 fractionally arranged in a plurality of locations, and a slave station 12 are respectively provided. And one or more local communication devices 13 connected to the
1 and the slave station 12 or between the slave station 12 and the slave station 12 are connected by the facing communication path 14.

In this communication system, the master station 11, the slave station 1
2. Each signal between the local communication devices 13 is transmitted on the communication path 14 as cellized data. The slave stations 12 distributed on the communication path 14 extract cells destined for the local communication apparatus 13 connected to the own station and output the cells to the local communication apparatus 13. Alternatively, a cell addressed to the local communication device 13 connected to another slave station 12 is sent to the communication path 14. The slave station 12 extracts the control management cell addressed to itself transmitted from the master station 11 and returns the control management cell to the master station 11. Then, a cell addressed to another slave station 12 or another slave station 12 to the master station 11
It relays the cell sent to it. In order to perform the relay exchange of these cells, the slave station 12 uses an ATM switch. The master station 11 also uses an ATM switch to relay and exchange control management communication cells between the master station 11 and each slave station 12 and communication cells between the local communication devices 13.

FIG. 2 is a block diagram showing a functional configuration of the master station 11 in the present system. 111-1,
Reference numerals 112-1, 111-2, and 112-2 denote physical layer converging portions, which are duplicated so as to be connected to two slave stations 12. In the receiving units 111-1 and 111-2,
A multiplexing module such as STS-3c or STM-1 is terminated, a cell carried in the payload of the module is taken out, and the cell is sent to the cell switch 113. In the cell switch 113, the receiving units 111-1, 11-1
1-2, celling / decellulating section 114, multiplexing / celling /
The cells input from the decellularizing unit 116 are transmitted to the transmitting units 112-1 and 112-2, the system control unit 115, and the local communication device control device 118 according to the cell destination. In the transmission units 112-1 and 112-2, the cell switch 113
STS-3c or STM-1
On the payload of a multiplexing module such as
Send to. The system control unit 115 performs control management of each slave station 12 by communicating with each slave station 12 and performs control management of each unit of the own device 11. The communication data for control management for each slave station is converted into a cell / decell
Is converted into cell data and sent to the cell switch 113. The cell from the cell switch 113 is converted into a data format that can be processed by the system control unit 115 by the celling / decellulating unit 114 and processed by the system control unit 115. The local communication device control device 118 controls and manages the local communication device 13. The communication data sent from the local communication device control device 118 is multiplexed with data from another local communication device control device 118 by the multiplexing / celling / decellularization unit 116 and transmitted to the cell switch 113. Can be Also, the cell switch 11
The cell sent from 3 to the multiplexing / cell-forming / de-celling unit 116 is distributed to each local communication device control device 118 according to the destination of the cell, decellulated, and processed by the local communication device control device 118. .

FIG. 3 is a block diagram showing a functional configuration of the slave station 12 in the present system. In the present system, 121-1, 122-1, 121-2, 122
Reference numeral -2 denotes a physical layer terminating unit, which is duplexed so as to be connected to two slave stations 12 or the master station 11 and the slave station 12. In receiving sections 121-1 and 121-2, ST
A multiplexing module such as S-3c or STM-1 is terminated, a cell carried in the payload of the module is taken out, and the cell is sent to the cell switch 123.
In the cell switch 123, the receiving units 121-1, 121-
2. The cells input from the cell-forming / de-celling unit 124 and the multiplexing-cell-forming / de-celling unit 125 are transmitted to the transmitting units 125-1, 125-2 and the device control unit 125 in accordance with the destination of the cell.
Side, to the local communication device 13 side. Transmission unit 121-
In 1,121-2, the cell input from the cell switch 123 is loaded on the payload of a multiplexing module such as STS-3c or STM-1, and transmitted to the slave station 12 or the master station 11. The device control unit 125 communicates with the master station 11 and controls and manages each unit of the own station 12. The control management communication data for the master station 12 is transmitted to the cell / decell
At 24, the data is converted into cell data and sent to the cell switch 123. The cell from the cell switch 123 is converted into a data format that can be processed by the device control unit 125 by the cell conversion / decellulation unit 124 and processed by the device control unit 125. The multiplexing / celling / decellling unit 126 converts the data from the local communication device 13 into cells, multiplexes the data with data from other local communication devices 13, and sends the cells to the cell switch 123. Further, the cells sent from the cell switch 102 to the multiplexing / celling / decellularizing unit 126 are distributed to the respective local communication devices 13 according to the destination of the cells, decellularized, and processed by the local communication device 13. .

As described above, the cell has information having different contents. Therefore, the cell is distinguished by the destination information of the VPI and VCI of the header in the cell. In the present invention, VPI
Is fixed to one value and distinguished by the value of VCI. When the VCI is 1 to 1023, it is a control management communication cell for each slave station, and when VCI = 1, the slave station 12-.
1 and a control management communication cell for the slave station 12-2 when VCI = 2. When the VCI is 1024 or more, each local communication device 13 or master station 1
It is a communication cell between communication devices within one.

FIG. 4 shows a master station 11 and a slave station 12 in a normal state.
2 illustrates a path of a control management communication cell between −2, that is, a state of a virtual path. The path 21 is from the master station 11 to the slave station 1
Working control path, path 22 transmitted to 2-2
Is a working control management path transmitted from the slave station 12-2 to the master station 11. Here, the switch of the master station 11 is connected to a control management communication cell (VCI =) from the master station to the slave station 12-2.
2) is output from port 25-1, and conversely, input port 25
The setting is made so that the cell of VCI = 2 received from −1 is taken into the system control unit 115 and processed.
In the slave station 12-2, the VC received from the port 25-5
The switch setting is performed such that the cell of I = 2 is taken into the device control unit 125 and the control management communication cell (VCI = 2) transmitted from the device control unit 125 is output from the port 25-5. Has been done. In the slave station 12-1, the cell of VCI = 2 input / output from the port 25-1 is set to be output from the port 25-2.

The path 23 extends from the master station 11 to the slave station 12.
-2, the path in the direction from master station 11 to slave station 12-2 is set from slave station 12-4 to slave station 12-2. However, it is not set in the master station 11. Similarly, child station 12
The path 24 in the direction of transmission from the slave station 12 to the master station 11 is set from the slave station 12-3 to the master station 11, and the slave station 1
2-2 is not set. That is, the switch of the transmitting station is not set with respect to the standby control and management communication paths 23 and 24. In the receiving station,
The switch is set so that the communication cell for control management can be taken into the device control unit 125 or the system control unit 115 from either port.

Slave station 12-1, slave station 12-3, slave station 12-
4 are similarly set. The control path for the active system is set so as to be always input / output from the port 25-1 of the master station 11, and the control path for the standby system is always set to the port 25-2 of the master station 11. Set to input / output more.

As described above, by setting the control management paths for all the slave stations 12 in one direction for the active system and in the reverse direction for the standby system, the communication path is disconnected when a failure occurs. At times, the control management path can be easily switched. A method for switching the control management path when a failure occurs will be described below.

The slave station 12 has a function of detecting a failure in the transmission path, and has a function of autonomously switching the control management path when detecting a failure in the transmission path. 5 to 12
Fig. 4 shows a state of switching the control management path when the slave station 12-2 and the slave station 12-3 detect a transmission path failure. In these figures, 11 is the master station, 12-1, 1
Reference numerals 2-2, 12-3, and 12-4 denote slave stations, reference numeral 13 denotes a local communication device, reference numeral 14 denotes an opposed duplex communication path for connecting the master station and the slave station or between the slave station and the slave station, and reference numeral 115 denotes a master station. A system control unit inside the station 11, and 125 are slave stations 12-1, 12-12
-2, 12-3, and 12-4. 25-1 and 25-2 are input / output ports of the master station 11 connected to the slave stations 12-1 and 12-4, respectively.
25-3 and 25-4 are the master station 11 and the slave station 12-2, respectively.
I / O port of slave station 12-1 connected to
25-6 are input / output ports of the slave station 12-2 connected to the slave stations 12-1 and 12-3, respectively, 25-7 and 25-.
Reference numeral 8 denotes an input / output port of the slave station 12-3 connected to the slave station 12-2 and the slave station 12-4, respectively, and reference numerals 25-9 and 25-10 connect to the slave station 12-3 and the master station 11, respectively. Slave station 12
−4 input / output port.

In FIG. 5, the transmission path between the slave stations 12-2 and 12-3 is disconnected, and the slave stations 12-2 and 12-3
OS (Loss Of Signal: signal loss) is detected, and it is possible to recognize a failure in the transmission path. FIG.
Control management paths 21, 22, 23, 24 of slave station 12-2
Is shown. In the slave station 12-2, since the working control paths 21 and 22 are not affected, the switching of the control management path is not performed, and the slave station 12-2 uses the working control path 22 to connect to the master station 11. Notify that a failure has occurred.

FIG. 7 shows the control management path 3 of the slave station 12-3.
1, 32, 33 and 34 are shown. In the slave station 12-3, the control paths for the active system 31 and 32 cannot be used, so that the control paths are switched. First, the slave station 12-
3 is set, the setting of the control management path 32 in the direction from the device control unit 125 of the slave station 12-3 toward the port 25-6 is released, and the setting is performed from the device control unit 125 to the port 25-8. The control management path 34 is set in the direction. Thereby, the control management path 34 in the direction from the slave station 12-3 to the master station 11 is established.

FIG. 8 shows a state where the control management path in the direction from the slave station 12-3 to the master station 11 is switched to the standby system 34. The slave station 12-3 uses the path 34 to notify the master station 11 that a failure has occurred, and instructs the slave station 12-3 to switch the control management path to the standby system 33. The master station 11 sets the switch of its own station, cancels the setting of the active control management path 31, and sets the control management path 33 in the direction from the system control unit 115 to the port 25-7. . This allows
The control management path 33 in the direction from the master station 11 to the slave station 12-3 is established. FIG. 9 shows a state where the control management path between the master station 11 and the slave station 12-3 has been switched to the standby system.

The master station 11 also switches the control management path to the standby system with respect to the slave station 12-4 downstream from the failure location. FIG. 10 shows the control management path 4 of the slave station 12-4.
1, 42, 43, and 44 are shown. First, the master station 11 sets its own switch, cancels the setting of the active control management path 41, and sets the control management path 43 in the direction from the system control unit 115 to the port 25-2. Do. Thereby, the control management path 43 in the direction from the master station 11 to the slave station 12-4 is established.

FIG. 11 shows a state where the control management path in the direction from the master station 11 to the slave station 12-4 has been switched to the standby system 43. The master station 11 uses the control management 43
To send data for instructing switch setting to the slave station 12-4. Thereby, in the slave station 12-4, the switch is set, and the device controller 125 of the slave station 12-4 is set.
Management path 42 in the direction from port 25-9 to port 25-9
Of the port 25-
The control management path 44 is set in the direction toward 10.
Thereby, the control management path 44 in the direction from the slave station 12-4 to the master station 11 is established. Slave station 12-4 is master station 1
1, the completion of the switching of the control management path is notified, and the master station 11 confirms that the control management path has been normally set by receiving this notification. FIG. 12 shows a state where the control management path for the slave station 12-4 has been switched to the standby systems 43 and 44.

Regarding a failure that the slave station 12 cannot detect,
By confirming the survival of each slave station 12 by the master station 11,
Failures can be detected. The master station 11 confirms the existence of each slave station by using the control path of the active system. The master station 11 periodically transmits survival confirmation request data to each slave station 12 through the control management path.
When receiving the survival confirmation request, the slave station 12 returns survival confirmation response data to the master station 11 through the control management path. When the survival confirmation response is received, the master station 11 determines that the network up to the slave station 12 is normal. If no survival acknowledgment was received,
It is determined that a failure has occurred in the transmission path between the slave station 12 that could not receive the survival confirmation response and the child station 12 one upstream of the slave station 12 or the slave station itself that could not receive the survival confirmation response.

FIGS. 13 to 15 show the failure detection method of the master station 11 and the switching of the control management path when the slave station 12 cannot detect the failure. FIG.
The state of an active control management path for each of the slave stations 12-1, 12-2, 12-3, and 12-4 is shown. 51,
52 is an active control management path for the slave station 12-1;
Reference numerals 21 and 22 denote active control and management paths for the slave station 12-2, 31 and 32 denote active control and management paths to the slave station 12-3, and 41 and 42 denote active control for the slave station 12-4. This is a management path, which is indicated by one line in the figure.
To the slave stations 12-1, 12-2, 12-3, and 12-4 and the slave stations 12-1, 12-2, 12-3, and 12
-4 to the master station 11. here,
A failure has occurred in the slave station 12-2. The survival confirmation is normally performed for the slave station 12-1.
The normality of the network up to 1 is confirmed.
No survival confirmation response is returned from 2-2, 12-3, and 12-4, and a failure has occurred in the transmission path between the slave stations 12-1 and 12-2 or the slave station 12-2. Is determined.

The master station 11 has slave stations 12-2, 12-3, 1
The control management path of 2-4 is switched to the standby system. The procedure for switching the control management path is the same as in FIGS. Here, the slave station 12-2 does not return a control management path switching completion response, and the master station 11 can determine that the slave station 12-2 has a failure. As for the slave stations 12-3 and 12-4, the control management path is set normally, and the management of each slave station can be performed normally. FIG. 14 shows the slave stations 12-1 at that time.
12 shows the states of control management paths 12-3 and 12-4. Reference numerals 51 and 52 denote active control and management paths for the slave station 12-1, 23 and 24 denote standby control and control paths to the slave station 12-2, and 33 and 34 denote standby control for the slave station 12-3. The management paths 43 and 44 are standby control management paths for the slave station 12-4. In the figure, one line is used to connect the master station 11 to the slave stations 12-1, 12-2, 12-3, and 12-3. 1
The path to 2-4 and the slave stations 12-1, 12-2, 12
A path from -3, 12-4 to the master station 11 is shown.

As described above, even when the slave station 12 cannot detect a fault, the master station 11 detects the fault, detects the fault location, and switches the control management path,
Control and management of each slave station can be performed normally.

As described above, the working control path of the slave station 12 is set from one side of the loop, and the control management path of the standby system is partially cut off from the opposite direction of the loop. By setting, even when a failure occurs and the communication path is disconnected, the switch of the master station 11 and the slave station 1 are provided to each of the slave stations 12 downstream from the fault location.
By simply changing the setting of the second switch, the path can be switched to the standby control management path, and the control management function for the slave station 12 can be quickly restored.

Another method for constantly performing control management communication between the master station 11 and the slave station 12 will be described below.
VPI and VCI of the control management cell for each slave station 12
Uses two types for each slave station 12, one for the virtual path on one side of the loop and another for the virtual path on the other side of the loop. In the slave station 12, two types of VP
It has a function of processing I and PCI cells. The master station 11 also has two types of VPs for each slave station 12.
It has a function of processing I and VCI cells. In the embodiment of the present invention, the VPI is set to the same value for every slave station 12, and the value of the VCI is changed. The control management cell for the slave station 12-1 has VCI = 1 and 1
01, the control management cell for the slave station 12-2 is VCI
= 2 and 102, the control management cell for the slave station 12-3 is set as VCI = 3 and 103, and the control management cell for the slave station 12-4 is set as VCI = 4 and 104. FIG. 15 shows the state of the control management virtual path for the slave station 12-2.
1, 62, 63 and 64 are set.

Reference numeral 61 denotes a virtual path in the direction from the master station 11 to the slave station 12-2, 62 denotes a virtual path in the direction from the slave station 12-2 to the master station 11, VPI = 1, VCI
= 2. 63 denotes a virtual path in the direction from the master station 11 to the slave station 12-2, and 64 denotes a virtual path in the direction from the slave station 12-2 to the master station 11;
CI = 102. Other slave stations 12-1, 12-3, 1
Similarly, a virtual path for control management communication is set for 2-4. Here, even if a failure occurs in the transmission path between the slave stations 12-1 and 12-2, the virtual paths 63, 6
4, the control management communication can be performed. Conversely, even when a failure occurs in the transmission path between the slave stations 12-2 and 12-3, control management communication can be performed by using the virtual paths 61 and 62.

As described above, by setting the control management path of the slave station 12 from both sides of the loop, even if one communication path is disconnected due to a failure, the other communication path can be used. Thus, communication for control management can be performed.

[0050]

As described above, according to the present invention,
The system management center and the node devices, or the node devices are connected to each other via opposed communication paths to form a double loop network. When a failure occurs or the number of node devices increases or decreases, the two communication paths of the above loop structure are used. The system management center is distributed and arranged at a plurality of locations on the loop network because the route on the side opposite to the route in which a fault has occurred or the route to which the node device is added or removed is used. A plurality of node devices can always be controlled and managed. In addition, when a failure is detected, the system can be automatically and promptly reconfigured. In addition, it is possible to automatically detect a failure point and quickly respond to recovery from the failure without shutting down the system. Can build a system.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a functional configuration of a master station 11 of the communication system in FIG.

FIG. 3 is a block diagram showing a functional configuration of a slave station 12 of the communication system in FIG. 1;

4 is a diagram showing a master station 11 and a slave station 1 of the communication system shown in FIG.
The figure which shows the setting state of the control management path between 2-2.

FIG. 5 is a diagram showing an operation of recognizing a transmission path failure between the slave stations 12-2 and 12-3.

6 shows a master station 11 and a slave station 12 at the time of occurrence of a failure in FIG.
The figure which shows the setting state of the control management path between -2.

FIG. 7 shows a master station 11 and a slave station 12 when a failure occurs in FIG.
FIG. 3 is a diagram illustrating a path configuration before switching a control management path between -3.

FIG. 8 is a diagram illustrating a path configuration immediately after switching a control management path between a master station 11 and a slave station 12-3.

FIG. 9 is a diagram illustrating a path configuration after switching of a control management path between a master station 11 and a slave station 12-3 is completed.

10 shows a master station 11 and a slave station 1 at the time of occurrence of a failure in FIG.
FIG. 5 is a path configuration diagram before switching of a control management path between 2 and 4;

FIG. 11 is a diagram illustrating a path configuration immediately after switching a control management path between a master station 11 and a slave station 12-4.

FIG. 12 is a diagram illustrating a path configuration after completion of switching of a control management path between a master station 11 and a slave station 12-4.

FIG. 13 is a diagram illustrating a path configuration when a failure occurs in the slave station 12-2 when the master station 11 confirms the existence of the slave station 12.

FIG. 14 is a path configuration diagram after the completion of switching of the control management path between the master station 11 and the slave station 12 due to the occurrence of a failure in FIG.

FIG. 15 is a diagram showing another mode of setting a control management path when a parent station 11 confirms the existence of a child station 12;

FIG. 16 is a schematic configuration diagram of a conventional communication system of this type.

[Explanation of symbols]

11 System Management Center (Master Station) 111-1, 111-2 Receiving Unit 112-1, 112-2 Transmitting Unit 113 Cell Switch 114 Cellular / Decellularizing Unit 115 System Control Unit 116 Multiplexing / Cellularizing / Decellularizing Unit 118 Local communication device control device 12, 12-1,..., 12-4 Node device (slave station) 121-1, 121-2 Receiving unit 122-1, 122-2 Transmitting unit 123 Cell switch 124 Cellular / decellularizing Unit 125 Device control unit 126 Multiplexing / celling / decellularizing unit 13 Local communication device 14 Communication path 25-1,..., 25-10 I / O port 21, 22, 23, 24 For control and management of slave station 12-2 Paths 31, 32, 33, 34 Control management paths 41, 42, 43, 44 for slave station 12-3 Control management paths 5 for slave station 12-4 Survival confirmation virtual path control management path 61, 62, 63 and 64 slave station 12-2 about 52 slave station 12-1

Claims (7)

[Claims] 1. A plurality of node devices distributed and arranged at a plurality of locations, one or more local communication devices connected to each of the node devices, and a center for controlling and managing the node devices and the local communication devices. Device, comprising opposed communication path means for serially connecting between the node apparatus and between the center apparatus and the node apparatus, wherein the center apparatus and the node apparatus have two circuits accommodating the communication path means, The center device and the node device are arranged and connected in a double loop, and communication between the devices is performed by cell data. The node device communicates with the center device to control its own station. It has a control management function of performing management, and, according to the destination of the cell, a cell from the local communication device connected to the own station and a cell for control management of the own station. The cells received from the center device or another node device are mixed and transmitted to the center device or another node device without overlapping, or the cell received from the center device or another node device is transmitted to the own station. The center device controls and manages the node device through communication with the node device and controls and manages the own station, together with a control management function or cell switch means for transmitting to a local communication device connected to the own station. Having a system management function to perform, according to the destination of the cell, the cell for control management and the cell received from the node device are mixed without overlapping, transmitted to another node device, or the cell received from the node device In a communication system comprising cell switching means for transmitting to a system management function of its own station, the communication path means and When a failure occurs in each node device or when the node device is added / removed, of the two routes between the center device and the node device in the loop network, the faulty route or the increase / decrease A communication system characterized in that the center device can always control and manage each of the node devices by using a route opposite to the route on the reduced side. 2. The method according to claim 1, further comprising the step of changing the path setting of said cell switch means in said center device and said node device in the event of a failure by using said cell switch means of said center device and said node device. The communication system according to claim 1, wherein a path used for control management communication is switched. 3. A center device and a node device are provided with a function of detecting a failure of the communication path means in a physical layer terminating circuit. 2. The communication system according to claim 1, wherein a failure occurrence is notified to a center device, and the control management communication function between the center device and the node device is automatically restored. 4. The center device performs survival confirmation to the node device at regular time intervals, monitors a normal state of the network by receiving a response from the node device, and responds to the survival confirmation from the node device. The communication system according to claim 1, wherein a failure is detected by not receiving a response, and a failure location is detected. 5. The communication system according to claim 1, wherein the center device, the node device, and the communication path unit are realized by an ATM (Asynchronous Transfer Mode) switching function. 6. A virtual path for control management communication at normal time is set between the center device and the node device on only one side of the loop, and a virtual path for spare control management communication is set from the other side of the loop. The setting is made in a state where only a part of the halfway route is interrupted, and when a fault occurs and the virtual path for the normal control communication is cut off, or when the node device is added / removed, the normal control is performed. When disconnecting the communication virtual path, the center device or the node device sets the interrupted portion of the backup virtual path and completes the backup virtual path, so that the center device and the node 6. The communication system according to claim 5, wherein control management communication between the devices can be always performed. 7. A virtual path for control management communication is set between a center device and a node device on both sides of a loop, and when a failure occurs and one virtual path is cut off, or when the number of the node devices increases. 6. The communication system according to claim 5, wherein the control management communication between the center device and the node device can be always performed by using one of the virtual paths at the time of / reduction.