JPH05219035A - Line switching device - Google Patents

Abstract

(57) [Abstract] [Object] To provide an excellent line switching device having a simplified device configuration by sharing the recovery monitoring unit of the line switching device of a terminal that communicates via a main line with a plurality of lines. [Composition] On one terminal side, the communication path of the terminal 1 is provided with a main line 4 or a backup line 8 including modems 3 and 5.
And a line switching device 2 for sending test data to the main line to monitor the recovery of the main line 4 and connecting the communication path of the terminal 7 to the main line 4 or the backup line. It is configured to include a line switching device 6 which is connected to the line switching device 8 by switching to the test data transmitted from the line switching device 2.

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 a dedicated line when a failure of the 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 dedicated line to the backup line, the recovery monitoring unit conducted a recovery test on the dedicated line, and when the recovery from the failure was confirmed, the communication route was returned to the dedicated line.

[0003]

However, since the recovery monitoring unit of the conventional line switching device is necessary for each line and is provided in both communication devices for transmitting and receiving, in the case of a plurality of lines, the line is not available. A large number of switching devices are required, and in particular, in the case of a leased line with a low probability of failure, there will be many line switching devices that are rarely used.
There was a problem of excessive equipment.

The present invention is to solve the above-mentioned conventional problems, in which the recovery 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]

In order to achieve the above-mentioned object, the present invention is so arranged that one terminal side is connected by switching the communication path of the terminal to a main line or a backup line.
Connection means, recovery monitoring means for transmitting test data to the main line to monitor recovery of the main line, second connecting means for connecting the main line and the recovery monitoring means, and first and second connections. A first control means for giving a connection command signal to the means, and connecting to the other terminal by switching the communication path of the terminal to the main line or the backup line.
Connection means, a fourth connection means for forming a communication path for returning the test data transmitted from the recovery monitoring means, and a third connection means.
And second control means for giving a connection command signal to the fourth connecting means, and the recovery monitoring means collates the transmitted test data with the test data returned by the fourth connecting means and monitors the recovery. It is configured to do.

[0006]

According to the present invention, when a failure occurs in the main line, the backup line is switched to perform communication.
The test data is sent from one terminal to the main line where the failure occurred, the test data returned by the other terminal is collated with the sent test data, and the recovery of the main line is monitored and the test data When the matching results match a predetermined number of times, the backup line is switched to the main line.

[0007]

Embodiments of the present invention will now be described 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 connection device 2 and a modem 3. The other end of the leased line 4 is connected to the other data terminal 7 via the modem 5 and the line switching device 6. Furthermore, both line switching devices 2 and 6 are
It is 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 voice band signals by the modems 3 and 5 via the 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 shown in FIG. 1, and FIG. 3 shows the configuration of the line switching device 6 shown in FIG. In FIG. 2, 21 is a switch which is the first connecting means for switching and connecting the line from the data terminal 1 to the dedicated line 4 or the backup line 8, and 22 is an IS for connecting the data terminal 1 to a standard I interface.
It is a DN adapter. Reference numeral 23 is a dedicated line monitoring unit that is a line monitoring unit that monitors the communication state of the dedicated line 4, 24 is a restoration monitoring unit that is a restoration monitoring unit that monitors restoration of the failure of the dedicated line 4, and 25 is restoration for a recovery test. It is a switch as a second connecting means for connecting the monitoring unit 24 to the dedicated line 4. Reference numeral 26 is a memory unit as a storage unit that stores data to be collated during recovery monitoring. Reference numeral 27 is a panel section as an operating means capable of manually switching the switches 21 and 25. Reference numeral 28 is control as first control means for switching the switches 21 and 25 in response to command signals from the dedicated monitoring section 23, the recovery monitoring section 24 and the panel section 27, and for giving a switching request signal to the ISDN adapter 22. It is a department.

Further, in FIG. 3, 61 is a data terminal 7.
A switch which is a third connecting means for switching and connecting the line from No. 1 to the dedicated line 4 or the backup line 8, and 62 is an I for connecting the data terminal 1 to a standard I interface.
It is an SDN adapter. 63 is the terminal 1 during the recovery test
It is a switch as a fourth connection unit that forms a loopback communication path in the dedicated line 4 in order to loop back the test data transmitted from. Reference numeral 64 denotes a control unit as a second control unit that switches the switches 61 and 63 according 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
Constantly monitors the communication state of the dedicated line 4, and when a failure occurs in the dedicated line 4, it detects this and notifies the control unit 28 of the failure occurrence. Upon receiving this notification, the control unit 28 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 leased line 4 via the modems 3 and 5 and the ISDN line 8
It is necessary to match the transmission conditions in order to make the line status of the same. Therefore, the transmission condition stored in the memory unit 26 is transmitted together with the switching request signal.

In FIG. 3, this switching request signal is ISD.
The control unit 64 received from the N adapter 62 determines whether the switching is possible, and if the switching is possible, the switch 61
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 out from the memory unit 26. After that, a connection command signal for switching from the private 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 private line 4 to perform a recovery test. ..

FIG. 4 shows the 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 a switchback instruction from the panel unit 27 for the switches 21 and 25 (step S1), and if there is no switchback instruction, test data for leased line restoration monitoring is transmitted. Yes (step S2). Since the transmitted test data is looped back at 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 the counter (not shown) that counts the number of recovery monitoring of the dedicated line in the control unit 28 is incremented by one. However, if they do not match, the counter value is cleared to zero. Therefore, the addition result of the counter continuously indicates the number of times that the test result is normal. It is determined whether or not the addition result of this counter has reached a predetermined number of times determined in advance (step S5). If the result has been reached, that is, if it has been normal for a predetermined number of times, the recovery operation of the dedicated line 4 is performed. In step S5, if the specified number of times has not been reached yet,
A recovery test is performed by moving to a subroutine (not shown) for transmitting test data. If there is a switchback instruction in step S1 and if the transmitted and received data do not match in step S4, the counter value is cleared (step S7). It should be noted that the prescribed number of times may be set to 1 and if the test result is OK even once, it may be determined that the recovery of the leased line 4 is completed.

FIG. 5 is a flow chart showing the operation of the loopback subroutine of the leased line of the control unit 64 of the terminal 7.
The return operation will not be described in detail because it has been described above. However, when the switching request signal is received from the ISDN adapter 62 (step S11), the switch 63 is given a command signal for returning the dedicated line (step S1).
2). Therefore, the response signal will be transmitted after this. Next, the recovery of the leased line 4 is completed and ISD is resumed.
When the switching request signal for switching from the N line 8 to the dedicated line 4 is received (step S13), the dedicated line loopback is canceled (step S14).

FIG. 6 is a partial block diagram of the line switching device 2a for accommodating a plurality of dedicated lines, and parts which are not directly related to restoration monitoring are omitted. The switch 25a connected to the recovery monitoring unit 24a includes switches 63A and 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, respectively. And 63C alternatively. The line switching device 2a includes a recovery monitoring timer (not shown).

Next, the operation of the configuration of FIG. 6 will be described with reference to the flow chart of the recovery monitoring dedicated line switching subroutine shown in FIG. When the line switching device 2a detects a failure in the leased lines 4A, 4B, and 4C and monitors the restoration of the leased line, the timer is timed out or waits for restoration monitoring (step S21), and the timer is used for restoration monitoring. It is activated (step S22). Next, it is judged whether or not there is a dedicated line for switching to the ISDN line, that is, a dedicated line being backed up by a switching request signal from the line switching device 2a on the originating side (step S23), and a dedicated line being backed up (for example, If there is a dedicated line 4A), recovery monitoring of the dedicated line 4A is set (step S24). Next, the recovery monitoring unit 24a is connected to the dedicated line 4
The transmission condition of A is set (step S25), and the unillustrated leased line changeover switch is switched to the leased line 4A (step S26). After that, the test data is transmitted from the restoration monitoring unit 24a, and the switch 6 of the line switching device 6A on the receiving side is transmitted.
The received test data and the transmitted test data are collated at 3A, and the recovery of the leased line 4A is monitored.

When the leased line 6B is set at the next timeout, the transmission condition of the leased line 6B is 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 leased line 6C is set, the transmission condition is set, the switch 25a is switched to the leased line 6C, and then the recovery test of the leased line 6C is performed. At the next timeout, the recovery test of the leased line 6A is performed again.

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

[0019]

As described above, according to the present invention, the recovery monitoring means for transmitting the test data to the other terminal through the main line is provided on one side of the terminal connected through the main line, The other terminal is equipped with a means for returning the test data from the recovery monitoring means.When a failure occurs in the main line, the main line is switched to the backup line, and then the test data is sent to the main line and returned. By comparing the test data sent with the sent test data and monitoring the recovery of the main line where the failure occurred,
There is an effect that a disaster 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. Therefore, especially in the case of a dedicated line with a low probability of failure, excessive equipment is installed. There is an effect that can be tested without.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a communication system to which a line switching device of 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.

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

FIG. 4 is a flowchart showing an operation of the line switching device of FIG.

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

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

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

[Explanation of symbols]

1, 7 Data terminal 2, 6, 2a, 6A, 6B, 6C Line switching device 3, 5, 3A to 3C, 5A to 5C Modem 4, 4A to 4C Dedicated line 8 ISDN line 21, 25, 25a, 61, 63 , 63A to 63C switches 22, 62 ISDN adapter 23 dedicated line monitoring unit 24, 24a restoration monitoring unit 26 memory unit 27 panel unit 28, 64 control unit

Claims (2)

[Claims] 1. A line switching device for performing communication between terminals via a main line and switching to a backup line when a failure occurs in the main line, wherein one terminal side has a communication path of the terminal. To the main line or the backup line for connection, and a recovery monitoring unit for transmitting test data to the main line to monitor the recovery of the main line; the main line and the recovery monitoring A second connection means for connecting the means and a first control means for giving a connection command signal to the first and second connection means, and the communication path of the terminal is provided on the other terminal side. Third connection means for switching and connecting to the line or the backup line, and fourth connection means for forming a communication path for returning the test data transmitted from the recovery monitoring means, A second control means for giving a connection command signal to the third and fourth connection means, wherein the recovery monitoring means collates the transmitted test data with the test data returned by the fourth connection means. A line switching device characterized by performing recovery monitoring. 2. The line switching apparatus according to claim 1, wherein the other terminal is a plurality of terminals that communicate with the one terminal via respective main lines.