JP3394660B2 - Redundant system switching method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for switching a duplex system composed of an active system device and a standby system device, and more particularly to protection of signals transmitted and received by the device during switching.

[0002]

2. Description of the Related Art Conventionally, in a communication system such as a switching system or a transmission system, two devices having the same structure are used separately for an active system and a standby system in order to improve system reliability. Uses a duplex system. FIG. 6 is a block diagram of a switching system using a conventional duplex system. This exchange system comprises a first control system 100, a second control system 200, and an accommodation device 300 accommodating a plurality of subscribers. Storage device 30
In order to control / monitor 0, when one control system is in the operating state, the other control system is in the standby state. Furthermore, the first control system 100 is a host device 100.
A, a relay device 100B, and a lower device 100C. Similarly, the second control system 200 also includes a higher device 200A, a relay device 200B, and a lower device 200C. In each system, the host device 100A,
The lower device 100C, 200C controls the accommodation device 300 by the 200A sending a command signal to the lower device 100C, 200C via the relay device 100B, 200B. On the other hand, the lower-level devices 100C and 200C send a response signal indicating the operation state of the accommodation device 300, etc.
It is sent to the higher-level devices 100A and 200A via 0B and 200B. Generally, the higher-level devices 100A and 200A need to control and monitor a large number of accommodation devices 300.
In order to reduce the load on the host devices 100A, 200A, etc.,
Sequence control, retransmission control, etc. are not adopted as the protocols for these communications. Therefore, the higher-level device does not give a number indicating the order of transmission to the command signal transmitted from the higher-level device to the lower-level device, and even if the response signal is not returned from the lower-level device, the same The command signal is not retransmitted to the lower device.

[0003]

In such a conventional duplex system, the relay device of the first system 100 when the first system 100 is in operation and the second system 200 is in standby. When a failure occurs in 100B, the relay device 100B is switched to the standby state, and the second system 20
It is necessary to switch the relay device 200B of 0 to the operating state. Even in such a case, the state of signals transmitted and received between the upper device and the lower device is not monitored at all. As a result, the relay device 100 that is in operation before the switching is performed.
The command signal received by B will be lost or discarded after switching. Therefore, there is a problem that after switching, the same command signal as the command signal that has been lost or discarded must be sent again.

[0004]

In order to solve the above-mentioned problems, in the switching method of the duplex system according to the present invention, only the command signal from another device is received before the standby device is switched to the operating state. In addition, the received command signal is switched to the pseudo operation state in which it is retained in its own device. By using such means, unlike the case where the transmission and reception of the command signal is restarted after the switching, the time required for transmitting and receiving the command signal can be shortened as a whole.

Further, after switching the stand-by device to the operating state, the command signal held in the device is started to be sent to another device. By using such means, all command signals to be transmitted can be transmitted in a short time.

[0006] Further, in order to prevent the standby device from switching to the pseudo-operation state, and another device which should send a response signal to the operating device not to send the response signal to the operating device, The response signal is retained in the own device. By using such a means, the response signal is transmitted to the operating device, and the operating device is switched to the standby state, so that the operation situation of transmitting the response signal is wasted. It is possible to avoid such a situation. On the other hand, after switching the stand-by device to the operating state, the other device transmits the held response signal to the device switched to the operating state. By using such means, the response signal to be transmitted can be surely transmitted without omission.

It should be noted that the instruction to switch to the pseudo operating state is notified by using the switching notice prior to the actual switching, and that the switching to the pseudo operating state is notified by using the switching notice reception. By using such means, it is possible to surely execute the switching to the pseudo operation state. Also, by confirming the switching to the pseudo state, it becomes possible to smoothly switch the sending direction of the command signal from the device in operation to the device in the pseudo operating state.

[0008]

DETAILED DESCRIPTION OF THE INVENTION

<Structure of Specific Example> A method of switching the duplex system according to the present invention will be described with reference to an embodiment. FIG. 1 is a block diagram of a duplex system of the present invention. This duplex system, which is an example applied to a switching system, has a plurality of accommodating devices 3 that accommodate a plurality of subscribers in a certain unit.
-1 to n, a first control system 1 for controlling and monitoring the accommodating devices 3-1 to n, and a second control system 2 similarly controlling and monitoring the accommodating devices 3-1 to n Has been done.
The first control system 1 is composed of a higher-level device 1A, a relay device 1B, and a lower-level device 1C. Similarly, the second control system 2 also has a higher-level device 2A, a relay device 2B, and a lower-level device 2C.
It consists of Both control systems 1 and 2 are host devices 1
A, 2A are relay devices 1B, 2B, lower devices 1C, 2
A command signal C is sent to each device in order to control and monitor C and the containing devices 3-1 to n. Then, each device receiving the command signal performs a predetermined process based on the command signal, and then sends a response signal R indicating the state of each device to the higher-level device 1A,
Reply to 2A.

<Operation of Specific Example> Next, the switching operation of the duplex system of the specific example will be described. In order to make the switching operation clearer, the switching operation will be described in comparison with the switching operation of the conventional duplex system. Further, the relay devices 1B and 100B of the operating first control system 1 and 100 are switched to the standby state, and the relay device 2 of the control system 2 and 200 which are in the standby state.
It is assumed that B and 200B are switched to the operating state.

FIG. 2 is an operation flow chart showing the switching operation of the duplex system of the concrete example, FIGS. 3 and 4 are operation time charts showing the switching operation of the duplex system of the concrete example, and FIG. It is an operation | movement flowchart which shows the switching operation | movement of the conventional duplex system. Hereinafter, description will be given along these operation flowcharts.

<Conventional Switching Operation> First, the switching operation of the conventional duplex system will be described with reference to FIG. Step S100: The host device 100A in the operating first control system 100 sends the command signal C0 to the relay device 100.
B, the data is sent to the accommodation device 300 via the lower device 100C. Step S101: The accommodating apparatus 300 that has received the command signal C0 returns a response signal R0 to the upper level apparatus 100A. Step S102: Similarly, the higher-level device 100A
Sends the next command signal C1 to the accommodation device 300. However, here, during the transmission of this command signal C1,
It is assumed that the relay device 100B has a failure.

Step S103: Host device 100A
Switches the relay device 100B in operation to the standby state without waiting for the response signal R1 from the accommodation device 300,
Also, the relay device 200B in standby is switched to the operating state. Thereby, the upper device 100A to the relay device 200B
The communication path of the lower device 100C to the accommodation device 300 is established. However, since the command signal C1 remains in the relay device 100B in the standby state, it is not sent to the accommodation device 300. Step S104: The high-level equipment 100A uses the relay apparatus 200B and the low-level equipment 100C that have entered the operating state
The command signal C2 is sent to the accommodation device 300.

Step S105: When the command signal C2 is received, the accommodating apparatus 300 sends the response signal R2 to the upper apparatus 10 via the lower apparatus 100C and the relay apparatus 200B.
Reply to 0A. In this way, the relay devices 100B, 20
The command signal C1 sent before switching 0B and the command signal C2 sent after switching 0B
After reaching 0 and performing predetermined processing, the response signal R
0 and R2 are returned to the higher-level device 100A. However, the command signal C1 transmitted during the switching is
Since 0 has not been reached, predetermined processing is not executed and the response signal R1 to be returned is not returned. Therefore, the command signals C0, C1 and C2 indicate one command as a whole,
In the case where the processes need to be performed in this order, even if the process based on the command signals C0 and C2 is performed, if the process based on the command signal C1 is not performed, no process is performed as a whole. It is considered that it was not done.
As a result, in such a case, the host device 100A
This means that the processing already performed on the basis of the command signals C0 and C2 must be canceled and all the command signals C0, C1 and C2 must be sent again.

<Switching Operation of Concrete Example> Next, FIGS.
The switching operation of the duplex system of the specific example will be described using FIG. Step S1: When a failure occurs in the relay device 1B in operation, the host device 1A switches the standby relay device 2B to the relay device 2B in advance before switching the standby relay device 2B to the operating state. It sends out a notice SP. By receiving the switching notice SP, the standby relay device 2B switches to the pseudo operation state. In this pseudo operation state, the relay device 2B can receive the command signal C from the higher-level device 1A instead of the relay device 1B, and can hold the received command signal C in its own device. . Therefore, it is not possible to transmit the command signal C to the lower device 1C or receive the response signal R from the lower device 1C. In addition, the relay device 2B that has switched to the pseudo operation state, in order to notify that the switching has been performed,
The switching advance notice acceptance SPR is transmitted to the higher-level device 1A. Upon receiving this switching advance notice acceptance SPR, the higher-level device 1A changes the destination of the command signal R from the relay device 1B to the relay device 2B.

Step S2: Similarly, the host device 1
A also sends the switching notice SP to the relay device 1B in operation. Upon receiving the switching notice SP, the relay device 1B
The command signal C is sent to the subordinate device 1C remaining in the device. Further, the relay device 1B is different from the lower device 1C in that
Response signal stop R requesting not to send response signal R
Send H. After receiving this response signal stop RH, the lower device 1C will not return the response signal R to the relay device 1B at all thereafter. The lower device 1C transmits a response signal stop completion RHE to notify the relay device 1B that the response signal stop RH has been received.

Step S3: The relay device 1B puts out all the response signals R stored in its own device to the higher-level device 1A, so that no response signal R remains inside. In this state, the relay device 1B transmits the switching advance notice acceptance SPR to the higher-level device 1A. Step S4: The host device 1A is the standby relay device 2
By sending the switch S to B, the relay device 2B is switched to the operating state. Thereby, the relay device 2
B starts sending out the command signal C received from the upper apparatus 1A and held in the pseudo operating state to the lower apparatus 1C. Note that the relay device 2B transmits the switching completion SE indicating the switching to the operating state to the higher-level device 1A.

Step S5: Further, the relay device 2B
Sends a response signal restart RR to the lower device 1C. As a result, the communication path of the upper device 1A to the relay device 2B to the lower device 1C to the accommodating device 3 is established. Then, by receiving the response signal restart RR, the lower device 1C starts sending the response signal R held by itself to the relay device 2B. The lower device 1C is
A response signal restart acceptance RRR indicating that the response signal restart RR has been received is sent to the relay device 2B. Step S6: Upon confirming that the relay device 2B has been switched, the higher-level device 1A also sends the switching S to the relay device 1B. The relay device 1B, which has switched to the standby state by receiving this switching S, transmits a switching completion SE to that effect to the higher-level device 1A.

<Effects of Specific Example> As described above, before switching the relay device in the standby state to the operating state, the relay device receives from the upper device only the command signal to be sent from the upper device to the lower device. In addition, the received command signal is switched to a pseudo operation state in which it is held without being sent to the lower device. As a result, unlike when the host device sends the command signal to the accommodation device for the first time after actually switching to the operating state, the host device transmits the command signal even before the relay device switches to the operating state. Since the relay device can send the command signal to the relay device and the relay device can receive the command signal, the time required for transmitting and receiving the command signal can be shortened as a whole. After switching the relay device to the original operating state, the suspended command signal is sent to the lower device. As a result, the command signal to be sent to the lower device can be quickly transmitted.

Further, the relay device in the standby state is switched to the pseudo operation state, and the lower device in operation does not send back the response signal to be returned to the relay device in operation, and is held in the lower device. I'll do it. This makes it possible to avoid a situation in which the response signal becomes invalid after switching as a result of returning such a response signal to the relay device in operation which should be switched to the standby state. On the other hand, after the relay device in standby is actually switched to the operating state, the operating lower device returns the response signal held in its own device to the relay device switched to the operating state. This makes it possible to reliably return the response signal to be returned to the host device without omission.

The host device sends a switching advance notice to switch the relay device to the pseudo operation state, and also returns the switching advance notice acceptance signal to notify that the relay device has switched to the pseudo operation state. As a result, it can be surely known that the switch has been switched to the pseudo operating state, and the sending direction of the command signal can be surely switched from the relay device in operation to the relay device in the pseudo operating state.

In the specific example described above, the control system is a host device,
It is composed of a relay device and a lower device. But,
It is also possible to configure only the upper device and the lower device. In this case, the upper device sends the command signal C to the lower device that has switched to the pseudo operation state, and the lower device holds the received command signal C in its own device. Then, after actually switching to the operating state, predetermined processing is performed in accordance with the suspended command signal. Accordingly, it is not necessary to send and receive the command signal after switching the device, and thus it is possible to immediately execute the process based on the command signal after switching the device.

[Brief description of drawings]

FIG. 1 is a block diagram of an example duplex system.

FIG. 2 is an operation flowchart of a duplex system of a specific example.

FIG. 3 is an operation time chart (No. 1) of the duplex system of the specific example.

FIG. 4 is an operation time chart (No. 2) of the duplex system of the specific example.

FIG. 5 is an operation flowchart of a conventional duplex system.

FIG. 6 is a block diagram of a conventional duplex system.

[Explanation of symbols]

1 First control system 2 Second control system 1A, 2A Host device 1B, 2B relay device 1C, 2C lower device 3 Housing device

Claims (8)

(57) [Claims] 1. A relay device for relaying a command signal and a response signal to and from an upper device and a lower device,
A method of switching a duplex system in which one relay device is in an operating state and the other relay device is in a standby state, in which a standby relay device receives only a command signal sent from the host device. A switching method of a duplex system, comprising: a step of switching to a pseudo operation state in which the relay apparatus can be suspended and a step of switching a relay apparatus in the pseudo operation state to an operation state. 2. The method according to claim 1, further comprising: after the relay device in the pseudo operation state is switched to the operation state, the relay device transmits a command signal held in the pseudo operation state to the lower device. A method for switching a redundant system, which is characterized in that 3. The low-order device according to claim 1, wherein after the relay device in standby is switched to a pseudo-operation state, a response signal to be transmitted by the low-order device to the relay device in operation is A method of switching a duplex system, comprising: 4. The sub-device according to claim 3, wherein the lower-layer device switches the response signal held in the lower-layer device to the operating state after the relay device in the pseudo-operating state switches to the operating state. A method of switching a duplex system, comprising the step of transmitting to a relay device. 5. The switching device according to claim 1, wherein the step of switching the standby relay device to a pseudo operation state comprises the step of sending a switching advance notice to the standby relay device for switching the relay device. By doing so, there is a step of switching the standby relay device to a pseudo operation state, and a step of sending a switching advance notice indicating that the relay device has switched to the pseudo operation state. System switching method. 6. A duplex system in which, of two lower-level devices that transmit and receive command signals and response signals to and from a higher-level device, one of the lower-level devices is in an operating state and the other lower-level device is in a standby state. And a step of switching a lower device in a standby state to a pseudo operation state in which only a command signal sent from the upper device can be received and held, and a lower device in the pseudo operation state. A method for switching a redundant system, comprising the steps of switching to an operating state. 7. The method according to claim 6, further comprising the step of executing a process based on a command signal suspended in the pseudo operation state after the low order apparatus in the pseudo operation state is switched to the operation state. A method for switching a redundant system characterized by the above. 8. The switching of the standby lower device to the pseudo-operation state according to claim 6, wherein the upper device sends a switching notice to notify the standby lower device of switching of the lower device. By doing so, there is a step of switching the standby lower device to a pseudo-operation state, and a step of transmitting a switching advance notice indicating that the low-order device has switched to the pseudo-operation state. System switching method.