JP2869944B2 - Line switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line switching device for switching a communication path to a backup line and performing a recovery test of the dedicated line when a failure of a dedicated line as a main line is detected.

[0002]

2. Description of the Related Art A conventional line switching device has a recovery monitoring unit for each dedicated line, and when a failure occurs in the dedicated line,
After switching from the leased line to the backup line, the recovery monitoring unit performs a recovery test on the leased line and confirms the recovery from the failure, and returns the communication path to the leased line.

[0003]

However, the recovery monitoring section of the conventional line switching device is required for each line, and is provided in both communication devices that perform transmission and reception. A large number of switching devices are required, especially in the case of a dedicated line having a small probability of occurrence of a failure, there will be many line switching devices that are used less frequently,
There was a problem of excess equipment.

[0004] The present invention is to solve the above-mentioned conventional problems, in which the restoration monitoring unit of the line switching device is shared by a plurality of lines,
An object of the present invention is to provide an excellent line switching device having a simplified device configuration.

[0005]

According to the present invention, in order to achieve the above object, communication is performed between terminals via a main line,
A line switching device for switching to a backup line when a failure occurs in the main line, wherein a first connection is provided to one terminal side by switching a communication path of the terminal to the main line or the backup line. Means for monitoring the communication state of the main line
Storage means for storing communication conditions of the main line
The main line monitoring means detects a fault in the main line.
Detects that the communication path is
When switching to the backup line, store it in the storage means.
Recovery monitoring means for transmitting test data to the main line in accordance with communication conditions to monitor the recovery of the main line, and second connection means for connecting the main line and the recovery monitoring means. A first control means for supplying a connection command signal to the first and second connection means, and connecting the other terminal side by switching a communication path of the terminal to the main line or the backup line. 3 connecting means and before
The communication path goes from the main line to the backup line.
A fourth connection unit that forms a communication path that loops back the test data transmitted from the recovery monitoring unit when the switching is performed; and a second control unit that supplies a connection command signal to the third and fourth connection units. The recovery monitoring unit is configured to perform recovery monitoring by comparing the transmitted test data with the test data returned by the fourth connection unit.

[0006]

According to the present invention, when a failure occurs in a main line, communication is performed by switching to a backup line.
The test data is transmitted from one terminal to the failed main line, the test data returned from the other terminal is compared with the transmitted test data, the recovery of the main line is monitored, and the test data is transmitted. If the matching result matches a predetermined number of times, the backup line is switched to the main line.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of a communication system using a line switching device according to an embodiment of the present invention. One data terminal (DTE) 1 is connected to one end of a dedicated line 4 as a main line via a line switching device 2 and a modem 3. The other end of the dedicated line 4 is connected to another data terminal 7 via a modem 5 and a line switching device 6. Further, both line switching devices 2 and 6 are ISDN
They are connected by a backup line 8 using an ISDN network having a basic interface. Normally, digital signals transmitted and received by the data terminals 1 and 7 are modulated and demodulated into signals in the voice band by modems 3 and 5 via line switching devices 2 and 6, respectively, and transmitted via the dedicated line 4.

FIG. 2 shows the configuration of the line switching device 2 of FIG. 1, and FIG. 3 shows the configuration of the line switching device 6 of FIG. In FIG. 2, reference numeral 21 denotes a switch as first connection means for switching and connecting the line from the data terminal 1 to the dedicated line 4 or the backup line 8, and 22 denotes an IS for connecting the data terminal 1 to a standard I interface.
It is a DN adapter. Reference numeral 23 denotes a dedicated line monitoring unit that is a line monitoring unit that monitors the communication state of the dedicated line 4, 24 denotes a recovery monitoring unit that is a recovery monitoring unit that monitors restoration of a failure of the dedicated line 4, and 25 denotes a recovery unit for a recovery test. It is a switch as second connection means for connecting the monitoring unit 24 to the dedicated line 4. Reference numeral 26 denotes a memory unit as storage means for storing data to be collated at the time of recovery monitoring. Reference numeral 27 denotes a panel unit serving as an operation unit capable of manually switching the switches 21 and 25. Reference numeral 28 denotes control as first control means for switching the switches 21 and 25 in response to command signals from the dedicated monitoring unit 23, the recovery monitoring unit 24, and the panel unit 27, and providing a switching request signal to the ISDN adapter 22. Department.

In FIG. 3, reference numeral 61 denotes a data terminal 7;
The switch 62 is a third connection means for switching and connecting the line from the terminal to the dedicated line 4 or the backup line 8.
SDN adapter. 63 is a terminal 1 at the time of the recovery test.
This is a switch as fourth connection means for forming a return communication path on the dedicated line 4 in order to return the test data transmitted from the server. Reference numeral 64 denotes a control unit as second control means for switching the switches 61 and 63 in response to a switching request signal from the ISDN adapter 61.

Next, the operation of the line switching devices 2 and 6 will be described. Usually a data terminal (simply called a terminal)
1 and the terminal 7 are connected via the dedicated line 4 by the switches 21 and 61. Dedicated line monitoring unit 23
Monitors the communication state of the dedicated line 4 at all times, and when a failure occurs in the dedicated line 4, detects this and notifies the control unit 28 of the occurrence of the failure. The control unit 28 receiving this notification calls the line switching device 6 via the ISDN adapter 22 and transmits a switching request signal for switching from the dedicated line 4 to the ISDN line 8. In this case, the line state of the dedicated line 4 via the modems 3 and 5 and the ISDN line 8
It is necessary to match transmission conditions in order to make the line state the same as the above. For this purpose, the transmission conditions stored in the memory unit 26 are transmitted together with the switching request signal.

In FIG. 3, this switching request signal is
The control unit 64 received from the N adapter 62 determines whether or not the switching is possible.
Is switched to the ISDN line 8 and the switch 63 is connected to the dedicated line 4 to form a loopback communication path. When this switching connection is completed, a response signal is transmitted to the line switching device 2. The control unit 28 receiving this response signal gives the switch 25 a connection command signal for connecting the dedicated line 4 and the recovery monitoring unit 24. In this case, the transmission conditions are read from the memory unit 26. Thereafter, a connection command signal for switching from the dedicated line 4 to the ISDN line 8 is given to the switch 21, and the recovery monitoring unit 24 sends test data to the terminal 7 via the dedicated line 4 to perform a recovery test. .

FIG. 4 shows a control unit 2 in the line switching device 2.
8 is an operation flowchart of a recovery monitoring subroutine of the dedicated line 4 of FIG. In FIG. 4, first, it is determined whether or not there is an instruction to switch back the switches 21 and 25 from the panel unit 27 (step S1). If there is no instruction to switch back, test data for monitoring dedicated line restoration is transmitted. (Step S2). Since the transmitted test data is looped back by the terminal 7, the loopback test data is received (step S3). Next, the transmission test data and the reception test data are collated, and it is determined whether or not they match (step S4). If the transmission and reception test data match, it is determined that the test result is normal, and the value of a counter (not shown) for counting the number of times of monitoring the recovery of the dedicated line in the control unit 28 is added. However, if they do not match, the counter value is cleared to zero. Therefore, the addition result of the counter indicates the number of times that the test result is normal continuously. It is determined whether or not the addition result of this counter has reached a predetermined number of times (step S5). If the number has reached, that is, if the number of times has been normal for a predetermined number of times, the dedicated line 4 is restored. In step S5, if the specified number has not been reached yet,
The process proceeds to a subroutine (not shown) for sending test data, and a recovery test is performed. If there is a switchback instruction in step S1, and if the transmission and reception data do not match in step S4, the value of the counter is cleared (step S7). If the specified number is set to 1 and the test result is OK even once, it may be determined that the restoration of the dedicated line 4 has been completed.

FIG. 5 is a flowchart showing the operation of the return subroutine of the dedicated line of the control unit 64 of the terminal 7.
Since the return operation has been described above, a detailed description thereof will be omitted. However, when a switching request signal is received from the ISDN adapter 62 (step S11), a dedicated line return instruction signal is given to the switch 63 (step S1).
2). Therefore, the response signal will be transmitted thereafter. Next, after the restoration of the leased line 4 is completed,
When a switching request signal for switching from the N line 8 to the dedicated line 4 is received (step S13), the return of the dedicated line is canceled (step S14).

FIG. 6 is a partial block diagram of a line switching device 2a accommodating a plurality of dedicated lines, and a portion not directly related to recovery monitoring is omitted. The switches 25a connected to the recovery monitoring unit 24a are respectively connected to the switches 63A, 63B of the line switching devices 6A, 6B, and 6C from the modems 5A, 5B, and 5C via the dedicated lines 4A, 4B, and 4C from the modems 3A, 3B, and 3C. And 63C. The line switching device 2a includes a recovery monitoring timer (not shown).

Next, the operation of the configuration shown in FIG. 6 will be described with reference to the flowchart of the recovery monitoring dedicated line switching subroutine shown in FIG. When the line switching device 2a detects a failure of the dedicated lines 4A, 4B, and 4C and monitors the recovery of the dedicated lines, it waits for a timer to time out or waits for recovery monitoring (step S21). Activate (step S22). Next, based on the switching request signal from the line switching device 2a on the calling side, it is determined whether or not there is a dedicated line for switching to the ISDN line, that is, whether there is a dedicated line being backed up (step S23). If there is a dedicated line 4A), recovery monitoring of the dedicated line 4A is set (step S24). Then, a dedicated line 4 is connected to the recovery monitoring unit 24a.
A transmission condition of A is set (step S25), and a dedicated line switch (not shown) is switched to the dedicated line 4A (step S26). Thereafter, the test data is transmitted from the recovery monitoring unit 24a, and the switch 6 of the line switching device 6A on the receiving side is transmitted.
Returning at 3A, the received test data and transmission test data are collated, and the restoration of the dedicated line 4A is monitored.

When the dedicated line 6B is set at the next timeout, the transmission conditions of the dedicated line 6B are set, and the switch 25
After switching a to the dedicated line 6B, a recovery test of the dedicated line 6B is performed. In the next timeout, the dedicated line 6C is set to set the transmission conditions, and after the switch 25a is switched to the dedicated line 6C, a recovery test of the dedicated line 6C is performed. At the next timeout, the recovery test of the dedicated line 6A is performed again.

As described above, when monitoring the recovery of a plurality of dedicated lines, a timer is set, and the recovery monitoring is performed while sequentially switching the plurality of dedicated lines when the timer times out.

[0019]

As described above, according to the present invention, on one side of a terminal connected via a main line, recovery monitoring means for transmitting test data to the other terminal via the main line is provided. The other terminal is provided with a means for returning the test data from the recovery monitoring means, and when a failure occurs on the main line, after switching from the main line to the backup line, the test data is transmitted to the main line and the return is made. It compares the test data sent with the transmitted test data and monitors the restoration of the failed main line.
There is an effect that a failure recovery test can be easily performed.

Further, even when a plurality of main lines are accommodated, the recovery monitoring means can be shared by the plurality of main lines. It has the effect of being able to test without the need.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a communication system to which a line switching device according to the present invention is applied.

FIG. 2 is a block diagram of a line switching device on one side of the terminal shown in FIG. 1;

FIG. 3 is a block diagram of a line switching device on the other side of the terminal shown in FIG. 1;

FIG. 4 is a flowchart illustrating an operation of the line switching device of FIG. 2;

FIG. 5 is a flowchart showing an operation of the line switching device of FIG. 3;

FIG. 6 is a block diagram of a part of a line switching device accommodating a plurality of lines.

FIG. 7 is a flowchart showing an operation of the line switching device of FIG. 6;

[Explanation of symbols]

1, 7 Data terminal 2, 6, 2a, 6A, 6B, 6C Line switching device 3, 5, 3A-3C, 5A-5C Modem 4, 4A-4C Dedicated line 8 ISDN line 21, 25, 25a, 61, 63 , 63A-63C Switch 22, 62 ISDN adapter 23 Dedicated line monitoring unit 24, 24a Recovery monitoring unit 26 Memory unit 27 Panel unit 28, 64 Control unit

Claims (2)

(57) [Claims] 1. A line switching device that performs communication between terminals via a main line and switches to a backup line when a failure occurs in the main line. First connection means for switching and connecting to the main line or the backup line, and a main unit for monitoring a communication state of the main line.
A line monitoring means for storing communication conditions of the main line;
Storage means, and the main line monitoring means
Detects a line failure, and switches the communication path from the main line.
When switching to the backup line, the storage
The main test data in accordance with communication conditions stored in the stage
Recovery monitoring means for transmitting to the in-line to monitor the recovery of the main line, second connection means for connecting the main line and the recovery monitoring means, and a connection command to the first and second connection means. A first control means for supplying a signal, a third connection means for switching the communication path of the terminal to the main line or the backup line and connecting to the other terminal side, and the communication path being connected to the main line. From the back
Fourth connection means for forming a communication path for returning the test data transmitted from the recovery monitoring means when switching to the up line, and second control for providing a connection command signal to the third and fourth connection means Means for monitoring the restoration by comparing the transmitted test data with the test data returned by the fourth connection means. 2. The main terminal according to claim 1, wherein said one terminal has a main circuit.
A plurality of the other terminals are connected via a line,
If one of the main lines fails,
When switching to the corresponding backup line, the second
Connecting means of the recovery monitoring means and the failure
Line switching apparatus according to claim 1, wherein that you connect the main line.