JPS6133035A - Circuit test system - Google Patents

Abstract

PURPOSE:To shorten the time needed for study of fault factors for a communication system where the lines are concentrated in multiplex to a trunk circuit, by performing a loop-back test through a control means via another normal circuit in case a fault of the trunk circuit is detected by a monitor means. CONSTITUTION:Data given from a communication controller 1 is supplied to a multiplex line concentrator 3 via low-speed circuits 2-1-2-n and 2-(n+1)-2-2n. These low-speed circuits are multiplexed independently of each other. The multiplexed circuits are supplied to a multiplex line concentrator 7 via modulation/demodulation devices 4 and 10, trunk circuits 6 and 12 and modulation/demodulation devices 5 and 11 of a counter station. The concentrator 7 separates the circuits into low-speed circuits 8-1-8-n and 8-(n+1)-8-2n and transmits them to terminal equipments 9-1-9-n and 9-(n+1)-9-2n respectively. The concentrators 3 and 7 contain monitor means to detect the fault and its recovery of the trunk circuit. When a fault of the trunk circuit is detected by the monitor means, an indication is given to the controller provided to each modulation/demodulation device. Then the controller uses another normal trunk circuit to perform a passing test and a loop-back test from both directions of the own station and a counter station.

Description

TECHNICAL FIELD The present invention relates to a line testing method, and more particularly to a method for testing a trunk line when a fault occurs, including deterioration of trunk line quality, in a multiplexing line concentrator that has a plurality of trunk lines.

BACKGROUND OF THE INVENTION In general, a multiplexing line concentrator is installed facing a terminal device and a communication control device provided at a center station via a communication path consisting of a modem, a relay line, and a modem.

Furthermore, a method has already been proposed in which a plurality of communication paths are provided between multi-electrification line concentrators, and when a failure occurs in one communication line, the lines are multiplexed and concentrated on another normal communication line.

However, regarding the content of the failure, the extent of the failure, and the isolation of the failure location for the communication channel where the failure occurred, it is difficult to determine the details of the failure, the extent of the failure, and the location of the failure.・This method involves manually conducting a line test for each (opposite station), and also conducting the same line test from both stations to isolate the fault location.

In systems using conventional multiplex concentrators, when a failure occurs in a communication path, such as when the line quality of a relay line deteriorates, the problem is avoided by multiplexing and concentrating on another communication path, but if the cause of the failure is due to force majeure. It is necessary to determine whether the problem is temporary, or whether it is due to a failure in each device that makes up the communication path.

However, in order to investigate the cause of this problem, it is necessary to manually set loopback points in each device on the communication path, and to conduct line tests by maintenance personnel at both the local station and the opposite station. Therefore, if the cause of the failure is a failure of the equipment, it will take time to resolve the problem, and a state of low data transmission efficiency will continue for a long time, resulting in a decrease in system throughput. A disadvantage is that maintenance personnel must be assigned to both the station and the opposing station.

OBJECT OF THE INVENTION The object of the present invention is to automatically perform a pass test and a loopback test sequentially from both sides of the communication path without human intervention in the event of a failure in the communication path in a data transmission system using a multiplex concentrator. An object of the present invention is to provide a line testing method that enables prompt fault isolation and recovery, improves the throughput of a data communication system, and shortens the time during which efficiency drops.

The line test method according to the present invention includes a monitoring means for detecting failure and restoration of a trunk line, and a control means for instructing a modulation/demodulation means to start and end loopback control. This system is characterized in that it is configured so that a pass test and a loopback test are sequentially performed in both directions between the local station and the opposite station using a relay line.

Example Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing an online system according to the present invention. However, in order to simplify the explanation, the number of relay lines is assumed to be two, which is the minimum number required for the system of the present invention.

In the figure, data from communication control device 1 is sent to low-speed line 2.
-1 to 2-n and 2-(n+1) to 2-(2n) after being input to the multiplexing line concentrator 3, the low-speed line 2-1
Data from ~2-n and low-speed line 2-(n+1) ~2(
2n) are multiplexed separately and sent to the modem devices 4, 5, the trunk line 6, and the modem device 10.1.
1 and the multiplexing line concentrator 7 of the opposite station via the relay line 12.
is input. The terminal equipment 9 is separated into low-speed lines 8-1 to 8-n and 8-(n+1) to 8-(2n).
-1 to 9-n and 9-(n+1) to 9-(2n).

Conversely, the terminal devices 9-1 to 9-n and 9-(n+
The data of 1) to 9-(2n) is sent to the communication control device 1 through the reverse route to the above, and is sent to the terminal devices 9-1 to 9-(2n).
9-(2n) and the communication control device 1 mutually transmit data.

FIG. 2 is a block diagram showing the configuration of the multiplexing line concentrators 3 and 7 for realizing the line testing method of the present invention. Second
The multiplexing line concentrator shown in the figure consists of level conversion circuits 13-1 to 13-(2n) provided for low-speed lines and a transmitting/receiving circuit 14.
-1 to 14-(2n), the line concentrator multiplexing circuit 15, the transmitting/receiving circuits 16 and 17 provided corresponding to the relay line, the level conversion circuits 18 and 19, the frame monitoring circuit 20, the control frame generation circuit 21, the control circuit 22, It is composed of a level conversion circuit 23 for loopback point setting/cancellation signals, a test start instruction circuit 24, and a display circuit 25.

Low-speed data from the communication control device 1 or terminal devices 9-1 to 9-(2n) is sent to level conversion circuits 13-1 to 13-(2n).
), and the level is converted by the transmitter/receiver circuits 14-1 to 14-(2
After being subjected to serial/parallel conversion in step n), it is input to the line concentrator multiplexing circuit 15. The concentrator multiplexing circuit 15 multiplexes the data of the transmitting/receiving circuits 14-1 to 14-n under the control of the control circuit 22, and sends the data to the transmitting/receiving circuit 16. On the other hand, the transmitter/receiver circuit 14-
The data (n+1) to 14-(2n) are multiplexed and then provided to the transmitting/receiving circuit 17. These two multiplexed data are sent to the transmitter/receiver circuit 16.

Parallel to serial conversion is performed at 17, and then level conversion circuit 18, 1
After level conversion in step 9, the signal is applied to relay line modem devices 4 and 10, respectively. Each multiplexed data sent from the multiplexing line concentrator 7 of the opposite station via the relay lines 6 and 12 is inputted to the transmitting/receiving circuits 16 and 17 via level converting circuits 18 and 19, where it is serial-parallel converted. After that, the line concentrator multiplexer circuit 15 separates the signals for each low-speed line, and the transmitter/receiver circuits 14-1 to 14-(2n) for each low-speed line perform parallel-to-serial conversion, and then pass through the level converter circuits 13-1 to 13-(2n). Send to each low-speed line.

As described above, the multiplexing and demultiplexing operation is the same as the conventional one.

In such a configuration, when quality deterioration occurs in the trunk line 6, the multiplexing line concentrator detects a large number of frame errors within a certain period of time by the function of the frame monitoring circuit 20, and then the control circuit 22 causes the line concentrating multiplexing circuit 15 to Then, the low-speed line data that has been multiplexed on the trunk line 6 as shown by the broken line (e) is condensed and multiplexed together with the remaining low-speed line data as shown by the dashed line (f).

Next, the line test method of the present invention will be explained.

In FIG. 1, if a failure occurs in the communication path of the relay line 6, the low-speed lines 2-1 to 2-
The data (2n) is condensed and multiplexed onto the trunk line 12, and data transmission continues. At this time, the display circuit 25 notifies maintenance personnel that a communication path failure has occurred. The maintenance person instructs the start of the line test using the test start instruction circuit 24. The test start instruction circuit 24 notifies the control circuit 22 of the start of the test. The control circuit 22 has a loopback point (a) of the line concentrator/demodulator 3 on the local station side, a loopback point (l) of the modulation/demodulation device 4 on the local station side, a loopback point (C) of the modulation/demodulation device 5 on the opposite station side, Loopback point of the line concentrator/multiplexer 7 on the opposite station side) (d) are set one by one.

The control circuit 22 instructs the transmitting/receiving circuit 16 to set the loopback point (a). Next, the control circuit 22 instructs the control frame generation circuit 21, and the control frame generation circuit 21 generates a flag character 26. as shown in FIG. Address 27. Control 2B, data section 29. A frame transmitting/receiving circuit consisting of a frame check sequence 30 and a flag character 31
Since the loopback point has been set, the transmitting/receiving circuit 16 receives the control frame in return. Frame monitoring circuit 20c, address and control of received frames.

Cyclic code check (e.g. CRC-CCI) on the data part
In the case of the TT method, the generator polynomial X" + X12 + X5
+1), and the calculation result is compared with the frame check sequence in the received frame to detect the presence or absence of a frame error.

The error detection signal is sent to the control circuit 22.

The control circuit 22 repeats the process from instructing the control frame generating circuit 21 to checking the frame monitoring circuit 20 a certain number of times (for example, 100 times), and displays the result on the display circuit 25. In addition, the control circuit 22 instructs the control frame generation circuit 21 to create a line test control frame on the opposite station side in order to conduct a line test from the line concentrator multiplexer 7 side in parallel with a line test from the line multiplexer 3 side. Instruct. The frame is sent to the relay line 12 via the same route as the data frame (transmission/reception circuit 17 - level conversion circuit 19), and is notified to the control circuit 22 of the line concentrator/multiplexer 7 on the opposite station side.

The control circuit 22 of the line concentrator 7 on the opposite station side performs a line test for the loopback point (a) in the same manner as the control circuit 22 of the line concentrator 3 on the local side. Regarding the result, the opposite station side line test control frame control circuit 22 displays the opposite station side result notification frame on the display circuit 25. However, regarding (a) and (d) (loopback point), the line test from the trunk line side is performed only when STI is used as the transmission timing.
When using T2, there will be a synchronization error, so the line test will be omitted.

Next, the control circuit 22 instructs the transmitter/receiver circuit 16 to cancel the loopback point (a), and then sets the loopback point (b).
The cancellation signal level conversion circuit 23 is instructed to send a local loopback control/setting signal to the trunk line modulation/demodulation device 4. The line test for the loopback point (b) is performed from both directions in the same way as the loopback point (a), and the results are displayed on the display circuit 25. To cancel the loopback point) (b), the control circuit 22 uses the loopback point setting/cancellation signal level conversion circuit 23.
This is done by instructing the relay line modem device 4 to send a local loopback control/release signal.

Next, regarding the setting of loopback point (c),
(e) The control circuit 22 instructs the control frame generation circuit 21 to create a setting control frame;
The control circuit 22 of the opposite station line concentrator 7 that received the frame performs the setting in the same manner as in the case of the loopback point (2), and after setting, returns a loopback point setting completion control frame.

For subsequent circuit tests, the loopback point (
Similar to a), the test results are displayed on the display circuit 25 from both directions.
to be displayed. To cancel the loopback point (C), the control circuit 22 uses the control frame generation circuit 21 in the same way as when setting it.
Instructs the creation of a loopback point (C) release control frame, and the control circuit 22 of the opposite station line concentrator 7 that received the frame cancels the loopback point (C) in the same manner as in the case of (b). Returns a loopback point release completion control frame.

Next, regarding the setting of the loopback point (d), the control circuit 22 instructs the control frame generation circuit 21 to create a control frame for setting the loopback point (d),
The control circuit 22 of the opposite station line concentrator 7 that has received the frame performs the setting in the same manner as in the case of the loopback point (a), and returns a loopback point setting completion control frame after setting the loopback point. Subsequent line tests are performed from both directions (loopback point) in the same manner as in (a), and the test results are displayed on the display circuit 25. To cancel the loopback point (d), the control circuit 22 loops back to the control frame generation circuit 21 in the same way as when setting it.
) Instructs the creation of a release control frame, and the control circuit 22 of the opposite station line concentrator 70 that receives the frame sets the loopback point) (a) in the same manner as in the case of (a),
After release, a loopback point release completion control frame is returned.

The automatic bidirectional line test is thus completed, and the control circuit 22 initializes the internal line test sequential schedule and returns the test mode to the normal mode. In normal mode, faulty lines can be monitored and monitored using already proposed methods.
Perform restoration.

As described above, in the present invention, when quality deterioration or failure occurs in the relay line between multiplexing line concentrators, one normal line among the many relay lines is used to perform bidirectional communication between the local station and the opposite station. Since line tests are automatically performed sequentially on faulty lines and the line diagnosis results are displayed, it is effective in reducing the number of maintenance personnel and the time it takes to investigate the cause of a fault, creating an economical online communication system. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an online system according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a multiplexing concentrator in the block of FIG. 1, and FIG. 3 is a relay in the system of FIG. 1. FIG. 2 is a diagram illustrating the configuration of a frame for data transmission and control used on a line. Explanation of symbols of main parts 1... Communication control device 3, 7... Multiplexing line concentrator 4
, 5.10.11...Modulation/demodulation device 15...Line concentration multiplexing circuit 20...Frame monitoring circuit 2■...Control frame generation circuit 22...Control circuit 24...Test start instruction circuit 25...display circuit

Claims (1)

[Claims] A line test method for a communication system in which each of the own station and the opposite station has a multiplexing line concentrating means and a modulation/demodulating means, and a plurality of low-speed lines are multiplexed and concentrated on at least two relay lines, and the relay line monitoring means for detecting failure and restoration of the relay line; and control means for instructing the modulation/demodulation means to start and end loopback control. and a line test method, characterized in that it is configured to sequentially perform a pass test and a loopback test from both sides of the opposite station.