JP2000261569A - Line switch device, communication system and line switch method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and surely switch a connection line. SOLUTION: In a line switch device 4, when an instruction to switch the connection line is received from a monitor center, a port state monitor part 13 detects a signal reaching an auxiliary side port 11 from the monitor center and reports it to a switch control part 14. The switch control part 14 reads a time difference between timing to switch the state (open/close) of the auxiliary side port 11 and timing to switch the connection destination of a line connection switch part 12 from the signal received from the port state monitor part 13 and sets it to a time counting part 22. The switch control part 14 switches the state (open/close) of the auxiliary side port 11 or connection destination of the line connection switch part 12 at the switch timing reported from the monitor center. The time counting part 22 counts the time and can switch the state (open/close) of the auxiliary side port 11 and the connection destination of the line connection switch part 12 at the prescribed switch timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line switching apparatus, a communication system, and a line switching method for increasing the operating rate of a system by switching between a dedicated line and a backup protection line.

[0002]

2. Description of the Related Art A communication system has been realized in which predetermined data is transmitted and received between a host station and a terminal station via a wired communication path to transmit and store information. In such a communication system, a dedicated line such as a high-speed digital line is used as a working line, and when a failure occurs in the dedicated line, the system is switched to a backup standby line such as a public ISDN line by remote control. There are those that increase the operating rate of

In such a communication system, when a failure occurs in a dedicated line or the failure of the dedicated line is restored, the line is switched from a monitoring center provided at a remote place to a line switching device of a host station and a terminal station. Is sent, and the line switching device switches the connection line.

Some line switching devices used in such communication systems switch connection lines as soon as an instruction to switch lines is received from a monitoring center.

[0005]

In the above prior art, the line switching device switches the line to be used immediately upon receiving an instruction to switch the line from the monitoring center, so that the communication quality is likely to deteriorate, and in the worst case, The host computer and terminal must be restarted.

A method is also conceivable in which the line switching device receives an instruction to switch the connection line from the monitoring center, confirms that the connection between the host station and the terminal station has been established, and then switches the line. The process for switching is complicated.

The present invention has been made in view of the above situation, and has as its object to provide a line switching apparatus, a communication system, and a line switching method capable of reliably switching connection lines with a simple operation.

[0008]

In order to achieve the above object, a line switching device according to a first aspect of the present invention is a line switching device for switching a connection line in response to an instruction from a monitoring center. A working port for transmitting and receiving data to and from the line terminating device accommodating; a protection port for transmitting and receiving data to and from the line terminating device accommodating the protection line; and a connection destination between the working port and the protection side. Line switching means for switching between ports and selecting a connection line;
A port monitoring unit that detects an input signal to the standby port; and a state (open) of the standby port when the input signal detected by the port monitoring unit is an instruction to switch a connection line from the monitoring center. / Close) and switching control means for switching the connection destination of the line switching means.

According to such a configuration, the switching control means can switch the state of the protection port and the connection destination of the line switching means based on the input signal of the protection port detected by the port monitoring means. As a result, the line switching device can switch the state of the standby port and the connection destination of the line switching unit at an appropriate timing in accordance with an instruction from the monitoring center, and can easily and reliably switch the connection line.

When the input signal detected by the port monitoring means is an instruction to switch the connection line from the monitoring center, the switching control means determines the timing of switching the state of the backup port from the instruction and the line switching. A time difference between the timing of switching the connection destination of the means and the timing of the standby port (open / close) and the connection destination of the line switching means are determined at a timing defined by the time difference and an instruction received from the monitoring center. It is desirable to switch between. Thus, the line switching device can surely switch the connection line without deteriorating the communication quality, and can easily switch the connection line without confirming that the connection has been established.

[0011] Storage means for storing a standard value of a time difference between a timing of switching the state of the protection port and a timing of switching the connection destination of the line switching means, wherein the switching control means detects the time difference by the port monitoring means. When the input signal is an instruction to switch the connection line from the monitoring center, the state (open / close) of the standby port and the state of the standby port are determined at the timing specified by the instruction and / or a standard value stored in the storage unit. The connection destination of the line switching means may be switched. As a result, the amount of data transmitted and received between the monitoring center and the line switching device using the communication line can be reduced, and the connection line can be quickly and reliably switched even when the connection line needs to be urgently switched.

When the switching control means receives an instruction to switch the connection line from the monitoring center, the switching control means indicates a time difference between the timing of switching the state of the protection port and the timing of switching the connection destination of the line switching means. It is determined whether or not the information is included, and when it is determined that the information is included, at the timing specified by the instruction received from the monitoring center and the time difference included in the instruction,
When the state (open / close) of the spare side port and the connection destination of the line switching unit are switched and it is determined that the line is not included, the instruction is specified by the instruction received from the monitoring center and the standard value stored in the storage unit. At the timing, the state (open / close) of the protection side port and the connection destination of the line switching means may be switched.

According to such a configuration, the line switching device uses the time difference between the switching timings designated by the monitoring center to connect the state of the standby port and the connection of the line switching means only when the switching timing should be adjusted. Switch the destination,
In other cases, the standard value held by the storage means can be used as the time difference of the switching timing. As a result,
It is possible to easily and reliably switch the connection line by reducing the amount of data transmitted and received using the communication line,
The switching timing can be flexibly changed as necessary, and the connection line can be switched more reliably.

A communication system according to a second aspect of the present invention is a communication system in which a connection line between a host station and a terminal station can be switched between a working line and a protection line. A line switching device that is installed and switches a connection line between the working line and the protection line,
A monitoring center for monitoring the failure of the working line and sending an instruction to switch the connection line to the line switching device, wherein the line switching device transmits and receives data to and from a line termination device that accommodates the dedicated line. Line switching for selecting a connection line by switching between a protection port for transmitting and receiving data between a working port and a line terminating device accommodating the protection line, and a connection destination between the working port and the protection port. Means, port monitoring means for detecting an input signal to the protection port, and connection between the status of the protection port (open / close) and the line switching means based on the input signal detected by the port monitoring means. Switching control means for switching the destination.

According to such a configuration, the switching control means of the line switching device switches the state of the protection port and the connection destination of the line switching means based on the input signal of the protection port detected by the port monitoring means. Can be done. The monitoring center can send an instruction to the line switching device so that the switching of the state of the standby port and the switching of the connection destination of the line switching unit can be appropriately performed. As a result, the line switching device can easily switch the connection line without confirming the establishment of the connection according to the instruction from the monitoring center. Further, the line switching device can switch the state of the protection side port and the connection destination of the line switching unit at different timings according to an instruction from the monitoring center, thereby preventing deterioration of communication quality at the time of line switching.

The instruction to switch the connection line sent to the line switching device by the monitoring center specifies the timing of switching the state (open / close) of the standby port or the timing of switching the connection destination by the line switching means based on time. You may. Alternatively, the instruction to switch the connection line sent to the line switching device by the monitoring center is an instruction to switch the state of the backup port (open / close) or the connection destination of the line switching unit at the time of receiving the instruction. May be.

When sending an instruction to switch the connection line to the line switching device, the monitoring center determines the timing of switching the state (open / close) of the protection side port and the timing of switching the connection destination by the line switching means. It is desirable to instruct the switching of the connection line by specifying the time difference. Thus, the line switching device can surely switch the connection line without deteriorating the communication quality, and can easily switch the connection line without confirming that the connection has been established.

The line switching device includes storage means for storing a standard value of a time difference between a timing of switching the state (open / close) of the protection side port and a timing of switching a connection destination of the line switching means. The control means, when the input signal detected by the port monitoring means is an instruction to switch a connection line from a monitoring center, at a timing defined by the instruction and / or a standard value stored in the storage means. The state of the port (open / closed) and the connection destination of the line switching means may be switched. As a result, the amount of data transmitted and received between the monitoring center and the line switching device using the communication line can be reduced, and the connection line can be quickly and reliably switched even when the connection line needs to be urgently switched.

When the input signal detected by the port monitoring means is an instruction to switch a connection line from the monitoring center, the switching control means switches the state (open / close) of the standby port when the input signal is an instruction to switch a connection line from the monitoring center. Determine whether or not contains information indicating the time difference between the timing and the timing of switching the connection destination of the line switching means,
If it is determined that the port number is included, the state (open / close) of the backup port and the connection destination of the line switching unit are switched at the timing specified by the instruction received from the monitoring center and the time difference included in the instruction. If it is determined that the port does not include the port, the state (open / close) of the standby port and the connection destination of the line switching unit are determined at the timing specified by the instruction received from the monitoring center and the standard value stored in the storage unit. May be switched.

According to such a configuration, the monitoring center specifies the time difference of the switching timing only when the switching timing in the line switching device should be adjusted, and in other cases,
The standard value held by the line switching device can be used as the time difference of the switching timing. As a result, it is possible to easily and reliably switch the connection line by reducing the amount of data to be transmitted and received using the communication line, and to flexibly change the switching timing as necessary to more reliably switch the connection line. Can be.

In a line switching method according to a third aspect of the present invention, in the line switching method for switching a connection line in accordance with an instruction from a monitoring center, a signal from the monitoring center is read and a port for connecting to a protection line is read. A time difference specifying step for specifying a time difference between a timing for switching the state (open / close) and a timing for switching the connection line, and a state (open / close) or a connection line of the port connected to the protection line according to an instruction from the monitoring center. Switching a first switching step;
At the time when the time difference specified in the time difference identification step elapses from the time point when the switching is performed in the switching step, the state (open / close) of the port connected to the protection line or the connection line And a second switching step of switching the one not switched in the first switching step.

A line switching method according to a fourth aspect of the present invention is a line switching method for switching a connection line in accordance with an instruction from a monitoring center, wherein a signal from the monitoring center is read, A judging step of judging whether or not a time difference between a timing of switching the state (open / close) of the port to be connected and a timing of switching the connection line is included; and the signal includes a time difference of the switching timing in the judging step. When it is determined that there is no time difference, a standard value reading step of reading a standard value of a preset time difference, and when it is determined in the determining step that the signal includes a time difference of switching timing, the signal is output from the signal. A time difference specifying step for specifying a time difference between switching timings, and a protection line according to an instruction from the monitoring center. The state of the port to connect to (open /
(Closed) or a first switching step of switching a connection line, and a time difference read out in the standard value reading step or a time difference read out in the standard value reading step or a time difference specified step in the first value switching step. At a point in time when the specified time difference elapses, the state (open / close) of the port connected to the protection line or the first among the connection lines
And a second switching step of switching a switch that has not been switched in the switching step.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a communication system to which a line switching device according to an embodiment of the present invention is applied will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a diagram showing a configuration of a communication system according to a first embodiment of the present invention. 1, the communication system includes a host computer 1, a terminal 2, a terminal control device 3, a line switching device 4, a dedicated line 5, and a backup ISDN.
A network 6 and a working line terminating device 7 for accommodating the leased line 5
And a protection line terminating device 8 accommodating the ISDN network 6
And a monitoring center 9.

In this communication system, the line switching device 4, the working line terminating device 7, and the protection line terminating device 8 are composed of a host station H having the host computer 1 and a terminal station having the terminal 2 and the terminal control device 3. And T respectively.

The host station H and the terminal station T communicate with the dedicated line 5 and the I
It is connected by the SDN network 6 and can mutually transmit and receive data, and can exchange stock information of sales articles, money amount information of a deposit account, and the like.

A line switching device 4 for switching lines in such a communication system will be described with reference to FIG. As illustrated in FIG. 2, the line switching device 4 includes a working port 10, a protection port 11, a line connection switching unit 12, a port status monitoring unit 13, and a switching control unit 14.

The working port 10 is used for data communication with the working line terminating device 7 containing a dedicated line 5 such as a high-speed digital dedicated line normally used for communication between the host station H and the terminal station T. For sending and receiving.

The backup port 11 is a backup ISDN network 6 used when a failure occurs in the leased line 5.
This is for transmitting and receiving data to and from the protection line terminating device 8 which accommodates the data. The port status monitoring unit 13 monitors the status (open / close) and the input signal of the standby port 11, and the port switching control unit 21 of the switching control unit 14 switches the port between open and closed.

Here, the opening of the port means that the protection side port 11 receives from the line connection switching unit 12 or the line terminating device 8 in order to enable data transmission and reception between the host station H and the terminal station T. This refers to the state in which the transmitted data passes.
On the other hand, closing a port refers to a state in which the protection-side port 11 does not pass data. At this time, the host station H and the terminal station T cannot transmit and receive data using the ISDN network 6.

The line connection switching unit 12 is composed of a switch and the like, and switches the connection line connecting the host station H and the terminal station T between the dedicated line 5 and the backup ISDN network 6. The line connection switching unit 12 selects a connection line by switching the connection destination between the working port 10 and the protection port 11 according to an instruction from the line switching control unit 20.

The port state monitoring unit 13 is provided with the standby port 1
This is for monitoring the input signal of one and the state (open / close) of the protection side port 11. The port status monitoring unit 13 receives the input signal received from the monitoring center 9 via the line terminating device 8 and the ISDN network 6 regardless of whether the status of the standby port 11 is open or closed. Is detected and notified to the switching control unit 14. Also, the port status monitoring unit 13
Is switched from the closed state to the open state, and the switching control unit 14 is notified.

The switching control unit 14 has a CPU (Central Proc).
essing unit) for controlling the operation of the line switching device 4. The line switching control unit 20
And a port switching control unit 21 and a clock unit 22.

The line switching control unit 20 causes the line connection switching unit 12 to switch the connection line according to the notification from the port state monitoring unit 13.

The port switching control section 21 switches between opening and closing of the standby port 11 in accordance with the input signal detected by the port state monitoring section 13.

The timer 22 measures the time difference between the switching timing of the state of the standby port 11 and the switching timing of the connection line of the line connection switching unit 12.

The monitoring center 9 shown in FIG. 1 monitors a failure occurring in the dedicated line 5, accesses the line switching device 4 installed in the host station H and the terminal station T from the ISDN network 6, and switches the line used. It is for instructing.
When the monitoring center 9 monitors the dedicated line 5 and detects the occurrence of a failure, the monitoring center 9 accesses the line switching device 4 and issues an instruction to switch the used line to the backup ISDN network 6.
At this time, first, the monitoring center 9 notifies the line switching device 4 of a time difference from the switching timing of the state of the standby port 11 to the switching timing of the line connection switching unit 12. Next, the monitoring center 9 instructs the line switching device 4 to open the backup port 11 and starts backup communication by the ISDN network 6.

At this time, the monitoring center 9 sets the standby port 1
The timing for switching 1 from closed to open may be specified and notified based on the time. The monitoring center 9
Alternatively, a notification for instructing the start of the switching operation may be sent in a timely manner to switch the state of the standby port 11 included in the line switching device 4 of the host station H and the terminal station T.

When the failure of the dedicated line 5 is recovered, the monitoring center 9 accesses the line switching device 4 and issues an instruction to switch the used line to the dedicated line 5. At this time, first, the monitoring center 9 sends the line connection switching unit 1 to the line switching device 4.
A time difference from the switching timing of 2 to the switching timing of the state of the standby port 11 is notified. Next, the monitoring center 9 instructs the line switching device 4 to switch the line connection of the line connection switching unit 12 and restore the communication using the dedicated line 5.

The operation of the communication system according to the first embodiment of the present invention will be described below. In this communication system, when the line switching device 4 switches the line, the monitoring center 9 notifies the time difference between the timing of switching the state of the standby port 11 and the timing of switching the connection line, and instructs the line switching, This is a system that enables simple and reliable line switching.

This communication system operates as follows when data is transmitted and received between the host station H and the terminal station T during normal times when the dedicated line 5 is available.

That is, the data transmitted by the terminal 2 installed in the terminal station T is transmitted to the terminal control unit 3 and the line switching unit 4 of the terminal station T via the line termination unit 7 of the terminal station T (working side).
Sent to The line termination device 7 (working side) of the terminal station T
The data is transmitted to the line terminating device 7 (working side) of the host station H via the dedicated line 5, and the data transmitted from the terminal 2 is transmitted to the host station H. The line termination device 7 (working side) of the host station H sends the data received from the terminal station T to the host computer 1 via the line switching device 4. This enables data transmission from the terminal station T to the host station H.

The data transmitted by the host computer 1 installed in the host station H is transmitted to the line terminating device 7 (working side) of the host station H via the line switching device 4 of the host station H.
Sent to Line termination device 7 of host station H (working side)
Transmits data to the line terminating device 7 (working side) of the terminal station T via the dedicated line 5 and sends data transmitted by the host computer 1 to the terminal station T. The line termination device 7 (working side) of the terminal station T sends the data received from the host station H to the terminal 2 via the line switching device 4 and the terminal control device 3. This enables data transmission from the host station H to the terminal station T.

Next, the monitoring center 9 detects that a failure has occurred in the dedicated line 5, which is the working line, and
Will be described when the connection line is switched to the ISDN network 6 which is a protection line.

When the monitoring center 9 detects that a failure has occurred in the dedicated line 5, the monitoring center 9 starts a failure switching command process shown in the flowchart of FIG.

When the monitoring center 9 starts the switching command processing at the time of failure, the monitoring center 9 makes a call to the protection line terminating device 8 installed in the host station H and the terminal station T via the ISDN network 6 to make a line. Access the switching device 4 (step S1).

When the monitoring center 9 accesses the line switching device 4, the monitoring center 9 notifies the time difference between the timing of switching the standby port 11 of the line switching device 4 from closed to open and the timing of switching the line connection switching unit 12 (step S2). ).

The monitoring center 9 is connected to the line switching device 4
Then, it notifies the timing of switching the protection side port 11 from closed to open, and instructs the switching of the used line (step S3). At this time, the monitoring center 9 may specify the timing of switching the standby port 11 from the closed state to the open state based on the time and notify the time. Further, the monitoring center 9 may send a notification instructing the start of the switching operation in a timely manner to switch the state of the backup port 11 included in the line switching device 4 of the host station H and the terminal station T.

Thereafter, the monitoring center 9 controls the line terminating devices 8 of the host station H and the terminal station T to establish a connection by a protection line between the host station H and the terminal station T, thereby switching at the time of failure. The command processing ends (step S4).

On the other hand, when a failure occurs in the dedicated line 5 and the line switching device 4 switches the line to be used to the protection line using the ISDN network 6, the line switching device 4 performs the following operation. At this time, first, the protection side port 11 of the line switching device 4 is in the closed state.

When the access from the monitoring center 9 is received while the standby port 11 is in the closed state, the line switching device 4 starts the line switching process at the time of failure shown in FIG.

When the line switching device 4 starts the line switching process at the time of failure, the port status monitoring unit 13
1 and detects a signal that arrives from the monitoring center 9 and notifies the switching control unit 14 (step S10).

The switching control unit 14 is a port state monitoring unit 13
The time difference between the timing of switching the state of the protection side port 11 and the timing of switching the connection line of the line connection switching unit 12 is read from the signal received from the controller (step S1).
1). The switching control unit 14 sets the time difference between the read switching timings in the timer unit 22 to prepare for switching the connection line.

The switching control unit 14 includes the port status monitoring unit 13
The timing for switching the state of the protection-side port 11 from the closed state to the open state is specified based on the signal received from the terminal (step S12). The switching control unit 14 sets the specified switching timing in the port switching control unit 21 and prepares to switch the state of the standby port 11.

The port switching control section 21 switches the state of the standby port 11 from closed to open according to the set switching timing (step S13).

The port state monitoring unit 13 is provided for the protection side port 1
It detects that the status of the port 1 has been switched from closed to open, and notifies the switching control unit 14 of the timing at which the status of the standby port 11 has been switched.

The switching control unit 14 is a port state monitoring unit 13
When the notification of the timing at which the state of the protection side port 11 is switched is received from the, the timer 22 starts counting time and waits for the time set in step S11 to elapse (NO in step S14).

When switching control unit 14 determines that time set by timer unit 22 has elapsed (YES in step S 14), line switching control unit 20 switches line connection switching unit 12.
Is switched from the working-side port 10 to the protection-side port 11, and the failure-time line switching process ends (step S15).

As a result, the line switching device 4 can easily switch the line connection without confirming that the connection between the host station H and the terminal station T has been established. In addition, the line switching operation can be performed with various delay times according to the time difference notified from the monitoring center 9, and the state of the communication system (communication amount, performance of the line switching device 4 when a failure occurs in the dedicated line 5). , Etc.) can be reliably switched.

This communication system operates as follows when data is transmitted and received between the host station H and the terminal station T during an emergency operation using a protection line using the ISDN network 6 as a connection line.

That is, the data transmitted by the terminal 2 installed in the terminal station T is transmitted to the line termination device 8 (standby side) of the terminal station T via the terminal control device 3 and the line switching device 4 of the terminal station T.
Sent to The line termination device 8 (standby side) of the terminal station T
The data is transmitted to the line termination device 8 (standby side) of the host station H via the ISDN network 6 and the data transmitted from the terminal 2 is transmitted to the host station H. The line termination device 8 (standby side) of the host station H sends the data received from the terminal station T to the host computer 1 via the line switching device 4. This enables data transmission from the terminal station T to the host station H.

The data transmitted by the host computer 1 installed in the host station H is transmitted to the line terminating device 8 (standby side) of the host station H via the line switching device 4 of the host station H.
Sent to Line termination device 8 of host station H (standby side)
Is the line termination device 8 of the terminal station T via the ISDN network 6.
(The spare side), and sends the data to the host computer 1
Sends the transmitted data to the terminal station T. The line termination device 8 (standby side) of the terminal station T sends the data received from the host station H to the terminal 2 via the line switching device 4 and the terminal control device 3. This enables data transmission from the host station H to the terminal station T.

Next, the monitoring center 9 detects that the failure of the leased line 5 which is the working line has been restored, and
Will be described when the connection line is returned to the dedicated line 5, which is the working line.

When the monitoring center 9 detects that the failure of the dedicated line 5 has been restored, the monitoring center 9 starts the switching command processing at restoration shown in the flowchart of FIG.

When the monitoring center 9 starts the switching command processing at the time of restoration, the monitoring center 9 makes a call to the protection-side line terminating device 8 installed in the host station H and the terminal station T via the ISDN network 6, and so on. Access the switching device 4 (step S2
0).

When the monitoring center 9 accesses the line switching device 4, the monitoring center 9 notifies the time difference between the timing of switching the connection line of the line connection switching unit 12 of the line switching device 4 and the timing of switching the state of the protection port 11 (step). S21).

The monitoring center 9 sets the line switching device 4
, The switching timing of the line connection switching unit 12 is notified to instruct the switching of the line to be used (step S2).
2). At this time, the monitoring center 9 may specify the timing of switching the line connection switching unit 12 based on the time and notify the same. In addition, the monitoring center 9 may send a notification instructing the start of the switching operation at an appropriate timing to switch the connection line of the line connection switching unit 12 included in the line switching device 4 of the host station H and the terminal station T. .

Thereafter, the monitoring center 9 controls the line terminating devices 8 of the host station H and the terminal station T to release the connection between the host station H and the terminal station T via the protection line (ISDN network 6). Then, the recovery switching command processing ends (step S23).

On the other hand, the line switching device 4
When switching from the protection line using the DN network 6 to the working line using the leased line 5, the following operation is performed. On this occasion,
First, the standby port 11 of the line switching device 4 is open.

When the access from the monitoring center 9 is accepted while the protection port 11 is open, the line switching device 4 starts the recovery line switching process shown in the flowchart of FIG.

When the line switching device 4 starts the line switching process at the time of restoration, the port status monitoring unit 13
1 and detects the signal that arrives from the monitoring center 9 and notifies the switching control unit 14 (step S30).

The switching control unit 14 is provided with the port status monitoring unit 13
The time difference between the timing of switching the connection destination of the line connection switching unit 12 and the timing of switching the state of the protection side port 11 is read from the signal received from the terminal (step S3).
1). The switching control unit 14 sets the time difference between the read switching timings in the timer unit 22 to prepare for switching the connection line.

The switching control unit 14 is a port state monitoring unit 13
A timing for switching the connection destination of the line connection switching unit 12 is specified from the signal received from the terminal (step S32). The switching control unit 14 sets the specified switching timing in the line switching control unit 20 and prepares to switch the state of the standby port 11.

The line switching control unit 20 switches the connection destination of the line connection switching unit 12 from the protection port 11 to the working port 10 according to the set switching timing (step S33).

The timer 22 measures the time from when the line switching control unit 20 switches the connection destination of the line connection switching unit 12, and waits until the time set in step S31 elapses (step S34). At NO).

When the switching control unit 14 determines that the time set by the timer unit 22 has elapsed (YES in step S34), the switching unit 14 switches the state of the standby port 11 from open to closed, and performs the line switching process during restoration. The process ends (step S35). As a result, the line switching device 4 returns to the dedicated line 5 and then disconnects the connection by the ISDN network 6, thereby preventing deterioration in communication quality and reliably switching the line connection. In addition, the line switching operation can be performed with various delay times according to the time difference notified from the monitoring center 9, and the state of the communication system (communication amount, performance of the line switching device 4 when the failure of the dedicated line 5 is recovered). , Etc.) can be reliably switched.

As described above, according to this communication system, when the monitoring center 9 sends a command to switch the connection line, the timing for switching the state of the protection side port 11 of the line switching device 4 and the line connection switching unit 12 Notification of the time difference with the timing of switching the connection line. The line switching device 4 switches the monitoring center 9 between the switching timing of the standby port 11 and the switching timing of the line connection switching unit 12.
The line switching operation is performed with the time difference notified from. As a result, it is possible to prevent the communication quality from deteriorating when the connection line is switched, to perform the reliable switching, and to easily switch the line without confirming the establishment of the connection.

(Second Embodiment) In the first embodiment, each time the monitoring center 9 instructs the switching of the line to be used, the line switching device 4 is connected to the line connection switching unit 12 and the standby port 11. It is necessary to notify the time difference of the switching timing and instruct the switching of the connection line. Generally, it is often urgent to switch the line in use. In such a case, the amount of data transmitted and received using the communication line should be minimized.

Therefore, the communication system according to the second embodiment, as shown in FIG. 7, replaces the line switching device 4 according to the first embodiment with data necessary for switching connection lines. Line switching device 4a having a function of retaining
Be prepared to have.

The line switching device 4a, as shown in FIG.
A control data storage unit 30 is provided in addition to the same configuration as the line switching device 4 according to the first embodiment.

The control data storage unit 30 is composed of a semiconductor memory or the like, and stores and holds in advance parameters used when the switching control unit 14 performs a line switching operation. The control data storage unit 30 stores the standard time difference between the switching timing of the state (open / close) of the standby port 11 and the switching timing of the connection destination of the line connection switching unit 12 when the line switching device 4a switches the connection line. Holds the value. The control data storage unit 30
The standard time difference is stored and held in advance based on a notification received in advance from the monitoring center 9 or a setting of an administrator, and can be read by the switching control unit 14.

Next, processing for switching a line in the communication system according to the second embodiment of the present invention will be described.

First, the operation when the monitoring center 9 detects that a failure has occurred in the dedicated line 5 and the line switching device 4a switches the connection line to the protection line using the ISDN network 6 will be described.

When the monitoring center 9 detects that a failure has occurred in the dedicated line 5, the monitoring center 9 starts a failure switching command process shown in the flowchart of FIG.

When the monitoring center 9 starts the switching command processing at the time of failure, the monitoring center 9 makes a call to the standby line terminating device 8 installed in the host station H and the terminal station T via the ISDN network 6 to make a call. Access the switching device 4a (step S4
0).

When the monitoring center 9 accesses the line switching unit 4a, the control data storage unit 30 of the line switching unit 4a
Then, it is determined whether or not a time difference different from the time difference of the switching timing held by is designated (step S41). Here, based on the result of monitoring the ISDN network 6 and the line terminating device 8, the monitoring center 9 determines whether to specify the time difference of the switching timing based on the traffic volume at the time of line switching, the state of the protection line terminating device 8, and the like. It is determined whether or not.

When the monitoring center 9 determines that the time difference of the switching timing is specified (YE in step S41).
S) Like the failure switching command processing of the first embodiment, the time difference between the switching timing of the state of the standby port 11 and the switching timing of the connection line of the line connection switching unit 12 is sent to the line switching device 4a. Notify (step S42).

On the other hand, if monitoring center 9 determines that the time difference between the switching timings is not specified (NO in step S41), it skips step S42 and proceeds to step S43.

The monitoring center 9 notifies the line switching device 4a of the timing of switching the protection side port 11 from closed to open, and instructs the line switching device 4a to switch the line in use (step S43).

Thereafter, the monitoring center 9 controls the line terminating device 8 (standby side) of the host station H and the terminal station T, and connects the standby line (ISDN network 6) between the host station H and the terminal station T. Is established, and the failure switching command processing ends (step S44).

On the other hand, when a failure occurs in the leased line 5 and the used line is switched to the protection line by the ISDN network 6, the line switching device 4a performs the following operation. At this time, first, the protection side port 11 of the line switching device 4a is in a closed state.

When the line switching device 4a receives an access from the monitoring center 9 while the standby port 11 is in the closed state, the line switching device 4a starts the failure line switching process shown in FIG.

When the line switching device 4a starts the line switching process at the time of failure, the port state monitoring unit 13 detects a signal reaching the protection port 11 from the monitoring center 9 and notifies the switching control unit 14 (step S50).

The switching control unit 14 is a port state monitoring unit 13
Is read (step S51).

The switching control unit 14 determines whether or not the read signal includes information indicating the time difference between the switching timing of the state of the standby port 11 and the switching timing of the connection destination of the line connection switching unit 12. (Step S52). Here, the signal read by the switching control unit 14 is transmitted to the monitoring center 9.
The switching control unit 14 can execute the above-described determination process by including an instruction signal indicating whether or not time difference information is included when transmitting the signal.

When the switching control unit 14 determines that the read signal contains information indicating the time difference between the switching timings (YES in step S52), the switching control unit 14 reads the time difference between the switching timings and sets the read time difference in the clock unit 22 ( Step S53).

On the other hand, when the switching control unit 14 determines that the read signal does not include the information indicating the time difference of the switching timing (NO in step S52), the switching control unit 14 reads the standard time difference from the control data storage unit 30 (step S52). Step S5
4). The switching control unit 14 sets the read standard time difference in the clock unit 22.

The switching control unit 14 is provided with the port status monitoring unit 13
A timing for switching the state of the protection-side port 11 from the closed state to the open state is specified based on the signal received from the server (step S55). The switching control unit 14 sets the specified switching timing in the port switching control unit 21 and prepares to switch the state of the standby port 11.

The port switching control section 21 switches the standby port 11 from closed to open in accordance with the set switching timing (step S56).

The port status monitoring unit 13 is provided with the protection side port 1
It detects that the state of the port 1 has been switched from the closed state to the open state and notifies the switching control section 14 of the timing at which the state of the standby port 11 has been switched.

The switching control unit 14 includes the port status monitoring unit 13
When the notification of the timing at which the state of the standby port 11 has been switched is received from the timer, the timer 22 starts measuring time and waits for the time set in the above step S53 or S54 to elapse (NO in step S57). ).

When switching control section 14 determines that time setting section 22 has elapsed (YES in step S 57), line switching control section 20 switches line connection switching section 12.
Is switched from the working-side port 10 to the protection-side port 11, and the failure-time line switching process ends (step S58).

Next, the monitoring center 9 detects that the failure of the dedicated line 5 which is the working line has been restored, and
The operation when a returns the used line to the dedicated line 5, which is the working line, will be described.

When the monitoring center 9 detects that the failure of the leased line 5 has been restored, the monitoring center 9 starts the restoration switching command processing shown in the flowchart of FIG.

When the monitoring center 9 starts the switching command processing at the time of restoration, the monitoring center 9 connects to the protection line terminating device 8 installed in the host station H and the terminal station T via the ISDN network 6, and connects to the line switching device 4a. Is accessed (step S60).

When the monitoring center 9 accesses the line switching device 4a, it determines whether or not a time difference different from the switching timing time difference held by the line switching device 4a is specified (step S61). Here, the monitoring center 9 monitors the dedicated line 5 and the line switching device 4a, and determines whether or not to specify the time difference of the switching timing based on the traffic volume at the time of line switching, the state of the line switching device 4a, and the like.

When the monitoring center 9 determines that the time difference of the switching timing is specified (YE in step S61).
S), like the recovery switching command processing of the first embodiment, a time difference between the timing of switching the line connection switching unit 12 and the timing of switching the state of the standby port 11 of the line switching device 4a is notified (S). Step S62).

On the other hand, if monitoring center 9 determines that the time difference between the switching timings is not specified (NO in step S61), it skips step S62 and proceeds to step S63.

The monitoring center 9 notifies the line switching device 4a of the timing of switching the connection destination of the line connection switching unit 12, and instructs the line switching device 4a to switch the connection line (step S6).
3).

Thereafter, the monitoring center 9 controls the line terminating devices 8 of the host station H and the terminal station T to release the connection by the protection line (ISDN network 6) between the host station H and the terminal station T. Then, the recovery-time switching instruction process ends (step S64).

On the other hand, the line switching device 4a sets the used line to I
When switching from the protection line using the SDN network 6 to the dedicated line 5, the following operation is performed. At this time, first, the protection side port 11 of the line switching device 4a is in an open state.

When the access from the monitoring center 9 is received while the standby port 11 is open, the line switching device 4a starts the line switching process at the time of restoration shown in FIG.

When the line switching device 4a starts the line switching process at the time of restoration, the port status monitoring unit 13 detects a signal reaching the protection port 11 from the monitoring center 9 and notifies the switching control unit 14 (step S1). S70).

The switching control unit 14 includes the port status monitoring unit 13
Is read (step S71).

The switching control unit 14 determines whether or not the read signal includes information indicating a time difference between the switching timing of the state of the standby port 11 and the switching timing of the connection destination of the line connection switching unit 12. (Step S72). Here, the signal read by the switching control unit 14 is transmitted to the monitoring center 9.
The switching control unit 14 is configured to be able to execute the above-described determination processing, for example, by having an instruction signal unit indicating whether or not time difference information is included in the transmission.

When the switching control unit 14 determines that the read signal includes information indicating the time difference of the switching timing (YES in step S72), it reads the time difference of the switching timing from the information (step S73). The line switching control unit 20 specifies the read time difference as the clock time.

On the other hand, when the switching control unit 14 determines that the read signal does not include the information indicating the time difference of the switching timing (NO in step S72), it reads the standard time difference from the control data storage unit 30 (step S72). Step S7
4). The switching control unit 14 sets the read standard time difference in the clock unit 22.

The switching control unit 14 is provided with the port status monitoring unit 13
From the signal received from, the timing for switching the connection destination of the line connection switching unit 12 from the protection port 11 to the working port 10 is specified (step S75).

The line switching control unit 20 switches the connection destination from the standby port 11 to the working port 10 to the line connection switching unit 12 in accordance with the switching timing of the connection destination specified from the signal received from the port status monitoring unit 13. (Step S76).

The timer 22 starts counting the time when the line switching control unit 20 switches the connection destination of the line connection switching unit 12, and waits until the time set in step S73 or step S74 elapses. (NO in step S77).

When the switching control unit 14 determines that the time set by the timer unit 22 has elapsed (YES in step S77), the state of the standby port 11 is switched from open to closed, and the line switching process at the time of restoration is performed. The process ends (step S78). Accordingly, the monitoring center 9 notifies the switching timing time difference only when switching is performed at a timing different from the standard value of the switching timing time difference held by the line switching device 4a, and switches the connection line to the line switching device 4a. Can be indicated.

As described above, according to this communication system, the line switching device 4a includes the control data storage unit 30. As a result, the line switching device 4a
The time difference between the switching timing 1 and the switching timing of the line connection switching unit 12 can be set in advance and held.
Therefore, when switching the line, the amount of data sent from the monitoring center 9 to the host station H and the terminal station T can be reduced, and the line can be switched more easily.

The present invention is not limited to the above embodiment, and various modifications and applications are possible. For example, in the above-described embodiment, the port state monitoring unit 13 detects that the state of the standby port 11 has been switched from closed to open, and the timer unit 22 starts clocking. However, the present invention is not limited to this. That is, the timing unit 22 may start timing from the timing at which the port switching control unit 21 switches the state of the standby port 11. In addition, an arbitrary method that is usually used, such as providing a reference time for starting timekeeping and switching the state of the protection port 11 and the connection destination of the line connection switching unit 12 according to the elapsed time from the reference time, can be applied.

[0124]

As described above, according to the present invention, when switching the line to be used, the line switching device switches the protection port in accordance with the instruction to switch the connection line received from the monitoring center and the timing of switching the connection line. Identify the time difference from the timing of switching, and switch the connection line. As a result, the line to be used can be switched easily and reliably without confirming that the data link has been established.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a configuration of a line switching device according to the first embodiment of the present invention.

FIG. 3 is a flowchart for explaining a failure-time switching command process executed by the monitoring center to switch a connection line from a working line to a protection line.

FIG. 4 is a flowchart for explaining a line switching process at the time of failure executed by a line switching device to switch a connection line from a working line to a protection line.

FIG. 5 is a flowchart for explaining a recovery switching command process executed by the monitoring center to switch the connection line from the protection line to the working line.

FIG. 6 is a flowchart illustrating a recovery-time line switching process executed by the line switching device to switch the connection line from the protection line to the working line.

FIG. 7 is a diagram showing a configuration of a communication system according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a line switching device according to a second embodiment of the present invention.

FIG. 9 is a flowchart for explaining a failure-time switching instruction process executed by the monitoring center to switch a connection line from a working line to a protection line.

FIG. 10 is a flowchart for explaining a faulty line switching process executed by the line switching device to switch the connection line from the working line to the protection line.

FIG. 11 is a flowchart illustrating a recovery switching command process executed by the monitoring center to switch a connection line from a protection line to a working line.

FIG. 12 is a flowchart illustrating a recovery-time line switching process executed by the line switching device to switch the connection line from the protection line to the working line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Host computer 2 Terminal 3 Terminal control device 4, 4a Line switching device 5 Dedicated line 6 ISDN network 7 Line termination device (working side) 8 Line termination device (standby side) 9 Monitoring center 10 Working side port 11 Reserved port 12 lines Connection switching unit 13 Port status monitoring unit 14 Switching control unit 20 Line switching control unit 21 Port switching control unit 22 Clock unit 30 Control data storage unit H Host station T Terminal station

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K014 AA01 CA06 EA04 FA01 HA00 5K034 AA05 DD01 EE13 GG02 MM05 5K048 AA04 BA31 DA01 DC07 EB02 EB10 HA01 HA02 5K101 KK11 MM01 MM07 NN21 QQ11 VV05

Claims (4)

[Claims] A line switching device for switching a connection line in response to an instruction from a monitoring center, comprising: a working port for transmitting / receiving data to / from a line termination device for accommodating a working line; and a line termination for accommodating a protection line. A protection port for transmitting and receiving data to and from a device; line switching means for switching a connection destination between the working port and the protection port to select a connection line; and detecting an input signal to the protection port. And a state (open / close) of the standby port and connection of the line switching means when an input signal detected by the port monitoring means is an instruction to switch a connection line from the monitoring center. Switching control means for switching a destination. 2. A communication system in which a connection line between a host station and a terminal station can be switched between a working line and a protection line, wherein the connection line is installed in the host station and the terminal station, and the connection line is connected to the working line and the protection line. And a monitoring center that monitors a failure of the working line and sends an instruction to switch the connection line to the line switching device, wherein the line switching device is a line termination device that accommodates the dedicated line. A working port that transmits and receives data to and from the working port; a protection port that sends and receives data to and from the line termination device that accommodates the protection line; and a connection destination switched between the working port and the protection port. Line switching means for selecting a connection line by means of a port, port monitoring means for detecting an input signal to the protection-side port, and based on the input signal detected by the port monitoring means. , A communication system wherein the comprising state of the spare side port (the open / closed) and switch control means to switch the connection destination of the channel switching unit, it is characterized. 3. A line switching method for switching a connection line according to an instruction from a monitoring center, wherein a signal from the monitoring center is read, and a timing and a connection line for switching a state (open / close) of a port connected to a protection line are switched. A time difference specifying step of specifying a time difference from timing; a first switching step of switching a state (open / close) of a port connected to a protection line or a connection line in accordance with an instruction from the monitoring center; and the first switching step When the time difference from the time when the switching is performed is performed and the time difference specified in the time difference specifying step elapses, the state (open / close) of the port connected to the protection line or the first of the connection lines is selected. A second switching step of switching the one not switched in the switching step; Comprising, line switching method characterized by. 4. A line switching method for switching a connection line in accordance with an instruction from a monitoring center, wherein a signal from the monitoring center is read and a state of a port connected to a protection line (open / closed) is added to the signal.
A determination step of determining whether or not a time difference between the timing of switching the connection and the timing of switching the connection line is included; and when it is determined in the determination step that the signal does not include the time difference of the switching timing, A standard value reading step of reading a standard value of the set time difference; and a time difference specifying step of specifying the time difference of the switching timing from the signal when it is determined in the determining step that the signal includes the time difference of the switching timing. A first switching step of switching a state (open / close) of a port connected to a protection line or a connection line in accordance with an instruction from the monitoring center; and a time counting from a point in time when the switching is performed in the first switching step. And specify the time difference read in the standard value reading step or the time difference specifying step. When the time difference elapses, the state (open / close) of the port connected to the protection line or the switching of the connection line that has not been switched in the first switching step is performed.
And a switching step.