JPH10262114A - Device and method for detecting failure in data communication exchange system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly judges a device where a failure occurs, to avoid the change-over of an exchange switch as much as possible and to prevent normal communication from being affected by synthetically recognizing overall transmission path states including a communication control processor, an exchange switch and a bus controller, etc., by means of transmission path state judgment results from the respective communication control processors. SOLUTION: The respective communication control processors 11 register the overall mounting states of the communication control processors 11 inside a data communication exchange system in a mounting state management part 111 and test data is exchanged with another communication control processor 11 by test data transmitting/receiving part 112. A central control processor 14 analyzes device states, based on test result reports from the respective communication control processors 11. Thus, the transmission path states of the exchange switch 13 and the bus controller 12 are synthetically recognized so that the failure of the bus controller 12 is correctly judged so as to suppress the change-over operation of the exchange switch as mucn as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for detecting a fault in a data communication switching system, and more particularly, to a method for connecting a plurality of communication control processors in a data communication switching system having a plurality of communication control processors therein. The present invention relates to a failure detection device and a failure detection method capable of detecting a failure of a bus control device when connected to a device.

[0002]

2. Description of the Related Art In recent years, in a communication control processing device of a data communication switching system, the device is modularized for each predetermined component in view of design change and ease of maintenance, and the device is mounted on a bus in a certain unit. By connecting them and interconnecting them via an exchange switch, a plurality of communication control processes are often distributed.

In such a distributed processing type data communication switching system, when a communication error occurs in any one of the communication control processing devices, a notification of the communication error is sent to the central control processing device, whereby the central processing unit is notified. The control processing device performs a failure process for each communication control processing device and a failure process for the exchange switch due to the notification from each communication control processing device.

Hereinafter, a failure detection device in such a conventional system will be described with reference to FIG.

FIG. 2 shows a central control processing unit and a plurality of communication control processing units which are connected in a decentralized state on respective buses and further connected to an exchange switch. 1 is a block diagram illustrating an example of a configuration of a distributed processing type data communication switching system that enables communication between communication control processing devices via a communication interface.

In FIG. 2, the conventional data communication effect system includes a plurality of communication control processors 11 connected to one bus for some groups and a plurality of buses provided for each bus. A bus controller for controlling the bus controller and a plurality of exchange switches for switching the bus controller;
And a central control processor 14 for connecting a plurality of communication control processors grouped for each bus in parallel on a bus basis.

The plurality of communication control processing devices 11 are distributed for each predetermined component in the data communication switching system,
FIG. 2 shows a case where six communication control processing devices 11 are provided. Each communication control processor 11 is assigned an identification number #n (n = 1, 2,..., 6).

When several communication control processors 11 are connected on a bus, the bus control unit 12 controls the data communication operation of the communication control processors under the bus. In FIG. 2, the data communication switching system includes two bus controllers, and each bus controller 12 is connected to three communication control processors 11 belonging to the bus controller 12. . Each bus control device 12 is given an identification number #n (n = 0, 1).

The exchange switch 13 is connected to the bus controller 12 of # 0 and the bus controller 12 of # 1, respectively, and has identification numbers # 1 and # of the communication control processors 11 belonging to the bus controller 12 of # 0. 2, # 3 and the identification numbers # 4 of the communication control processors 11 under the control of the bus controller 12 of # 1;
An exchange switch for exchanging data transfer between # 5 and # 6. FIG. 2 shows a redundant configuration in which two exchange switches are implemented in consideration of the occurrence of a device failure in the exchange switch 13, and an identification number #n (n =
0, 1) are given. Normally, one is in operation and the other is in standby, so that they are alternately started.

The central control processor 14 manages the entire data communication switching system in an integrated manner and controls all devices arranged in the switching system. Normally, each time the communication control processing device 11 periodically transmits test data with its own communication control processing device 11 as a communication partner, the communication control processing device 11 determines whether the test data has been transmitted normally. This determination is made by determining whether or not a response signal has been returned from the bus control device.

For example, when transmitting test data from the communication control processing device 11 having the identification number # 1 to the communication control processing device 11 having the identification number # 1, the communication control processing device 11 having the identification number # 1 transmits the test data. Test data addressed to one communication control processing device 11 is output. The test data passes through the bus control device 12 having the identification number # 0 and accommodates the communication control processing device 11 having the identification number # 1, and further passes through the exchange switch 13 and again through the bus control device 12 having the identification number # 0. Then, it is supplied to the communication control processing device 11 having the identification number # 1.

At this time, when the data is received by the communication control processing device 11 of the identification number # 1, the identification number # accommodating the communication control processing device 11 of the identification number # 1 that received the data.
0 from the bus control unit 12 via the exchange switch 13 in the same manner as described above.
A response signal is returned to the bus control device 12 having the identification number # 0 that accommodates the ID number # 1.
This is supplied to one communication control processing device 11.

On the other hand, if no test data is received, no response signal is returned. Therefore, identification number # 1
The communication control processing device 11 can determine whether the test data has been transmitted normally by determining whether the response signal has been returned.

When it is determined that the data is not transmitted normally, a notification that the data transmission is not normal is transmitted to the central control processing unit 14. The central control processing device 14 is, for example, the bus control device 12 having the identification number # 0.
When a notification of a transmission error is received from any one of the communication control processing devices 11 belonging to the group, it is determined that a failure has occurred in the bus control device 12 having the identification number # 0.

That is, as a cause of the occurrence of the transmission abnormality, a failure of the communication control processing device 11 for transmitting and receiving the test data, a failure of the bus control device 12 accommodating the communication control processing device 11 detecting the transmission abnormality, and Exchange switch 13
However, even if one of the communication control processors 11 belonging to the bus control device 12 detects a transmission error, it is difficult to determine which of these causes caused the transmission error.

However, in the same bus control device 12, the communication control processing device 1 belonging to the bus control device 12
The greater the number of transmission abnormalities detected from 1, the greater the possibility that a failure has occurred in the bus control device 12. In this way, the higher the possibility that a failure has occurred in the bus control device 12, the more the bus control device 12
The possibility of occurrence of a failure also increases with respect to the port of the exchange switch 13 connected to the switch. Therefore, when the exchange switch 13 has a redundant configuration, by switching the active exchange switch 13 to the standby exchange switch 13, an attempt is made to reconfigure the apparatus capable of normal communication.

[0017]

As described above, the fault detecting device in the conventional data communication switching system is:
A specific bus controller 12 provided in the switching system
For each of the communication control processing devices 11 in the group, the presence / absence of a transmission error at the time of test data transmission is determined, and when all the communication control processing devices 11 in the group of the bus control device 12 detect the test data transmission abnormality, It is determined that a failure has occurred in the bus control device 12. Also,
If the exchange switch 13 has a redundant configuration in the device configuration of the data communication exchange system, the failure of the port of the active exchange switch 13 connected to the bus control device 12 recognized as having a failure has occurred. Then, the exchange switch 13 is switched.

However, according to the configuration of the conventional fault detecting device having the above configuration, for example, even if the device in which the fault actually occurs is the specific bus control device 12, the fault is recognized as the fault in the exchange switch 13. And the replacement switch 13
There is a problem that switching is performed. When the exchange switch 13 is switched in such a situation, first, for example, in the communication control processing device 11 other than the communication control processing device 11 belonging to the bus control device 12 that has been recognized as having a failure, the exchange If the data being transferred between the communication control processing devices 11 is lost in the currently operating exchange switch 13 when the switch 13 is switched, there has been a problem that data retransmission processing frequently occurs.

Therefore, when a device failure occurs at any point in the data communication switching system, whether the device which has actually failed is the communication control processing device, the bus control device, or the switching device. There is a need for a failure detection apparatus and method in a data communication switching system that can more accurately determine whether the switch is a switch, avoid unnecessary switching of the switching switch as much as possible, and do not adversely affect normal communication. ing.

[0020]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a plurality of communication control processors each executing a predetermined communication control processing operation, and a plurality of these communication control processors. , A plurality of bus controllers for managing each of a group of processing devices connected to one bus as a group of several predetermined numbers, an exchange switch for exchanging these plural bus controllers, and a plurality of communication control units. In a fault detection device for detecting a fault in a data communication switching system including a central control processing device that performs fault detection and fault processing in each communication control processing device by connecting processing devices in parallel for each group, It is characterized by comprising means.

That is, (1) management means for recognizing and managing all communication control processing devices mounted in the data communication switching system by notification from the central control processing device, and (2) management means. Transmission path state determination means for determining a transmission path state between the communication control processing apparatuses by an operation of transmitting test data between the communication control processing apparatuses mounted in the obtained data communication switching system; (3)
And a device state analyzing means for comprehensively determining a transmission path state in each communication control processing device obtained by the transmission path state determining means.

According to a second aspect of the present invention, there are provided a plurality of communication control processing devices each of which executes a predetermined communication control processing operation, and the plurality of communication control processing devices are grouped into a predetermined number of one group. A plurality of bus control devices for managing each of the processing device groups connected to one bus, an exchange switch for exchanging and switching the plurality of bus control devices, and a plurality of communication control processing devices connected in parallel for each group and A method for detecting a failure in a data communication switching system including a central control processing device that performs failure detection and failure processing in the communication control processing device has the following steps.

That is, a first step of transmitting test data from each communication control processor to a transmission path pattern to be tested in advance, and the test data is normally transmitted based on the test data transmitted in the first step. A second step in which each communication control processing device determines whether or not the transmission has been performed. If it is determined in the second step that the transmission has not been performed normally, a test result report corresponding to the transmission path pattern on which the test was performed is sent to each communication control processor. A third step in which the communication control processing device notifies the central control processing device, and a fourth step of determining a specific communication control processing device in which the failure has occurred in the central control processing device based on the notification in the third step. And a step.

In the above configuration, the test data is transmitted to a predetermined transmission line pattern to be tested by the communication control processing device communication state determination means of each communication control processing device. Based on the test data, each communication control processing device determines whether the test data has been transmitted normally. When a result of the determination that transmission is not performed normally is obtained by this determination, a test result report corresponding to the transmission path pattern on which the test was performed is notified from each communication control processing device to the central control processing device. In the central control processing device, a device in which a failure has occurred is determined by the device state analysis means based on a test result report from each communication control processing device.

According to such a configuration, all transmission path states including the communication control processing apparatus, the exchange switch, the bus control apparatus, etc. are comprehensively recognized based on the transmission path state determination result from each communication control processing apparatus. Therefore, the failure of the bus control device can be accurately determined, and the switching operation of the exchange switch can be suppressed as much as possible.

[0026]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A preferred embodiment of the present invention will be described in detail.

FIG. 1 is a block diagram showing the configuration of a fault detecting device according to one embodiment of the present invention. FIG.
Is an example in which the present invention is applied to the distributed processing type data communication switching system of FIG. 2, and is characterized by the configuration of each communication control processing device 11 and central control processing device 14. . In FIG. 1, the characteristics of the communication control processing device 11 are as follows.
1 will be described as a representative example. In FIG. 1, each communication control processing device 11 is a mounting state management unit that registers the mounting states of all the communication control processing devices 11 mounted in the data communication switching system according to a notification from the central control processing device 14. Test data transmitting and receiving unit 1 for transmitting and receiving test data between the communication control unit 111 and another communication control processing device 11
12, the mounting state management unit 111 and the test data transmission / reception unit 1
12 is provided. Also,
The central control processing device 14 includes a device state analysis unit 141 that receives a test result report from each communication control processing device 11 and analyzes the device state based on the test result report.

A failure detection method as an operation of the failure detection device in the data communication switching system having the above configuration will be described.

This fault detecting method includes a first step of transmitting test data from each communication control processor to a transmission line pattern to be tested in advance, and a step of transmitting test data based on the test data transmitted in the first step. A second method in which each communication control processing device determines whether or not transmission has been normally performed;
When it is determined in the step and the second step that the transmission has not been performed normally, each communication control processing device notifies the central control processing device of a test result report corresponding to the tested transmission path pattern. The method includes a third step and a fourth step of determining a specific communication control processing device in which a failure has occurred in the central control processing device based on the notification in the third step.

In the first step, the mounting state management unit 111 is notified by the central control processing unit 14 when the communication control processing unit 11 of the own system is started up, and is installed in the data communication switching system. Of the communication control processing device 11 described above, and selects and manages the communication control processing device 11 to which the test data is to be transmitted, based on a predetermined transmission path pattern to be tested.

When a test data transmission request is generated, the test data transmission / reception section 112 executes the operation of generating and transmitting test data addressed to its own communication control processing device 11, and is managed by the mounting state management section 111. The test data is generated and transmitted to the communication control processor 11 corresponding to the transmission path pattern that is present. In addition, when test data addressed to the own communication control processing device 11 is transmitted, the test data transmission / reception unit 112 receives the test data and performs a predetermined reception processing operation.

The control unit 113 sets a transmission path pattern to be tested to the mounting state management unit 111, and periodically instructs the test data transmission / reception unit 112 to execute a test data transmission operation. .

In the second step, the apparatus state analysis unit 1
Reference numeral 41 analyzes the contents of the test result report based on a test result report notified when an abnormality in the transmission path is detected by the communication state determination unit between the communication control processing units performed in each communication control processing unit 11, and Judgment is made comprehensively, and a device which is considered to have an abnormality is determined.

A description will be given of a failure detection operation when a failure occurs in the bus control device 12 having the identification number # 0 in the above configuration. First, a description will be given of a determination operation of detecting an abnormality in a transmission path in the communication state determination unit between the communication control processing units in each communication control processing unit 11. FIG. 3 is a flowchart illustrating the determination operation of the third step performed by each communication control processing device 11 for detecting an abnormality in the transmission path.

The determining operation in the third step is shown in steps S1 to S10 in FIG. 3, and is started by the control unit 113 at predetermined intervals. In this determination operation, first, a process of reading the identification number of the own communication control processing device registered in a table or the like (not shown) is performed (step S1). Next, test data having the destination of the identification number of the communication control processing device is generated (Step S).
2). The content of the test data to be generated is significant in that an identification number is assigned to each of the communication control processing devices of the test data transmission source and the test data transmission destination. It may be something like this.

When the generation of the test data is completed, the test data is transmitted (step S3). The transmitted test data is sent to the exchange switch 1 via the bus controller 12 to which the communication control processor 11 is connected.
3 is transferred. Thereafter, by determining whether or not a response signal has been sent from the bus control device 12 to which the own communication control processing device is connected, a process of determining whether or not the test data has been normally transmitted is performed (Step S1). S4).
When receiving the test data, the test data transmitting / receiving unit 112 discards the test data.

If a response signal has been sent, it is determined that the test data has been transmitted normally, and the communication state determination operation in this cycle ends. On the other hand, if no response signal is sent, it is determined that the test data was not sent normally.

Next, a transmission path pattern as a test target managed in advance by the mounting state management unit 111 is read (step S5). The transmission path patterns to be tested include various patterns considered to be effective for analyzing a device in which a failure has occurred. For example, the communication control processing device 11 that has detected an abnormal transmission of test data is referred to. In this case, a transmission line pattern with another communication control processing device 11 belonging to the same bus control device 12 and a transmission line pattern with another communication control processing device 11 belonging to a different bus control device 12 Etc. can be considered. In step S5, it is determined whether or not the read transmission path pattern is completed. If not, the read transmission path pattern is valid (step S6).

Next, test data addressed to the identification number of the communication control processor 11 corresponding to the transmission path pattern determined to be valid is generated (step S7), and the test data is transmitted (step S8). ). Then, the transmission result of the test data based on the valid transmission path pattern is unconditionally set as the test result in the test result notification message (step S9). Here, the test operation for the transmission path pattern ends, and in step S5, processing for reading the next transmission path pattern to be tested is performed.

If it is determined in step S6 that the read transmission line pattern has been completed, the transmission control unit 11 checks the transmission line state in the communication control processing unit 11 which has detected an abnormal transmission of test data. All the test patterns have been completed.

Next, in the processing up to this point, the transmission result of the test data is set for each transmission path pattern, and the test result report including the test result notification message is transmitted to the central control processing unit 14. This is performed (step S10).

Next, based on the test result notification message of the test result report content notified from each communication control processing device 11, the device state determination operation of the fourth step of analyzing the device in which the fault has occurred is shown in FIG. Steps S21 to S32 of No. 4 will be described. When a test result notification message is sent from each communication control processing device 11, it is first registered in a test result notification message registration table in the central control processing device, and thereafter, the operation of determining the device state is executed. .

FIG. 4 is a flowchart showing a test result notification message analyzing operation executed in the device state analyzing unit 141 in the central control processing device 14. The operation in FIG. 4 is executed each time a test result notification message is sent from each communication control processing device 11. In FIG. 4, the identification number of the bus control device 12 is indicated by #i, and the identification number of the communication control processing device 11 is indicated by #j.

First, when a test result notification message is sent from the communication control processing device 11 which has detected a test data transmission error, the same identification number as that of the communication control processing device 11 which sent the test result notification message is used. The process of reading out the test result notification messages from all the communication control processing devices 11 connected to the bus control device #i from the test result notification message registration table is performed (step S21). In the test result notification message read in step S21, for example, a process of reading a test result notification message corresponding to the communication control processing device 11 with the smallest identification number #j in each communication control processing device 11 is performed (step S21). S22). Then, a process is performed to determine whether or not there is a test result notification message of the communication control processing device 11 having the identification number #j (step S23).

Next, in step S23, when it is determined that there is a test result notification message, the identification number # is used to perform a detailed analysis of the test result notification message.
The transmission line pattern corresponding to the j communication control processing device 11 is read (step S24), and a process of determining whether or not the read transmission line pattern is completed is performed (step S25). If it is determined that the read transmission path pattern is not completed, a process of determining a faulty device is performed based on the transmission path pattern and the contents of the test result in the transmission path pattern (step S).
26).

Next, in step S26, the failure count corresponding to the device determined to have a failure is updated (step S27), and step S2 is performed again.
At 4, the next transmission path pattern is read. That is, in step S27, the device that updates the failure count is the result of determining a failure device for each transmission line pattern that is one test unit in the communication control processing device 11 having the identification number #j.

On the other hand, in step S23, as a result of determining whether or not there is a test result notification message of the communication control processor 11 having the identification number #j, if it is determined that there is no test result notification message, the identification number is determined. Assuming that the test result notification message has not been notified from the communication control processing device #j of #j, the process proceeds to the next process of determining the communication control processing device 11. Similarly, step S25
In this case, even when the transmission path pattern has been completed, the process proceeds to the process of making a determination by the next communication control processing device 11.

Next, when the analysis of the test result notification message for the communication control processor 11 having the current identification number #j is completed, the identification number #j is updated, and the test result of the next communication control processor 11 is updated. The process proceeds to the analysis of the notification message (step S28). When the identification number #j is updated, the communication control processing device 11 of the identification number #j is actually updated.
Is implemented (step S2).
9). Here, when it is determined that the communication control processing device 11 with the updated identification number #j is mounted,
Proceeding to step S22 again, the updated identification number #
The test result notification message of the communication control processing device 11 of j is analyzed.

Conversely, if it is determined in step S29 that the communication control processing device 11 with the updated identification number #j is not installed, it belongs to the bus control device 12 with the current identification number #i. All communication control processing devices 11
Is completed, the identification number #i is updated, and the process proceeds to the analysis process for the next bus control device 12 (step S3).
0).

Next, the identification number # in step S30
When updating i, it is determined whether or not the bus control device 12 with the identification number #i is actually installed (step S31). Here, when it is determined that the bus control device 12 with the updated identification number #i is mounted,
Proceeding to step S21 again, the updated identification number #i
The analysis processing of the test result notification message to each communication control processing device 11 belonging to the bus control device 12 is performed.

On the other hand, if it is determined in step S31 that the bus control device 12 with the updated identification number #i is not installed, the device for all the bus control devices 12 installed in the exchange is controlled. Since the state determination process has been completed, a device having a final failure is determined based on the failure count number based on the analysis results so far (step S32).

Thereafter, similarly, each time a test result notification message is sent, the above-described determination operation is repeated.

According to the apparatus and method for detecting a failure in a data communication switching system according to one embodiment described in detail above,
The following effects are obtained. (1) First, a test data transmission operation in a predetermined cycle in the communication control processing device can detect a device abnormality separately from a normal data transmission operation. Can be freely detected regardless of other devices. (2) When a transmission abnormality is detected by the test data transmission operation, the transmission operation of the test data is performed between the other communication control processing devices, but some transmission line patterns to be tested are prepared in advance. This makes it possible to collect effective data when analyzing a certain failure of the device thereafter. (3) Even when preparing a transmission line pattern for performing the test, only the effective transmission line pattern can be set efficiently by managing the communication control processing device mounted in the exchange. (4) Further, by analyzing valid data,
Since the state of the transmission line surrounding the exchange switch and the bus control device can be comprehensively recognized, the failure of the bus control device can be accurately determined, so that the switching operation of the exchange switch can be suppressed as much as possible.

As described above, one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, and any modifications and changes can be made without departing from the gist of the present invention. You can do it. (1) For example, in the above embodiment, the case where the transmission abnormality of the test data is determined based on whether or not the response signal is returned from the bus control device 12 has been described. However, the present invention may determine whether there is a transmission abnormality by determining whether test data has been received. (2) In the above embodiment, when the communication control processor 11 transmits the test data based on the transmission path pattern, the test result notification message is set unconditionally regardless of the presence or absence of the transmission abnormality, and the central control processing is performed. The case of notifying the device 14 has been described. However, only when there is a transmission abnormality, the central control processing device 14 may be notified. (3) In the above embodiment, the central control processor 1
In the update of the fault count of the faulty device in No. 4, the case where the faulty device is determined for each transmission path pattern and the fault count is updated has been described. However, when there are a plurality of transmission line patterns that are considered to be the same, the failure count may be updated using the plurality of transmission line patterns as one transmission line pattern. (4) Further, in the above-described embodiment, a case has been described in which, in the update of the fault count of the faulty device in the central control processing device 14, the bus control device 12 performs the device state determination operation with one reference. However, the communication control processing device 11
May be used as one criterion to perform the device state determination operation.

[0055]

As described above in detail, according to the present invention, it is possible to recognize detailed transmission path conditions from each communication control processing device and to collect data effective for device failure analysis processing. It is possible to accurately determine the location of an actual failure in a data communication switching system, thereby avoiding unnecessary switching operations of the switching switch as much as possible and not adversely affecting normal communication. It is possible to provide a failure detection device and method that can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of a failure detection device in a data communication switching system according to an embodiment.

FIG. 2 is a block diagram illustrating a configuration of a conventional failure detection device.

FIG. 3 is a flowchart illustrating a communication state determination operation in the failure detection device according to the embodiment.

FIG. 4 is a flowchart illustrating a device state determination operation in the failure detection device according to the embodiment.

[Explanation of symbols]

 Reference Signs List 11 communication control processing device 12 bus control device 13 exchange switch 14 central control processing device 111 mounting state management unit (management unit) 112 test data transmission / reception unit (transmission line state determination unit) 113 control unit (transmission line state determination unit) 141 device State analysis unit (device state analysis means)

Claims (4)

[Claims] 1. A plurality of communication control processing devices each of which executes a predetermined communication control processing operation, and a plurality of communication control processing devices connected to one bus as a predetermined number of groups. A plurality of bus control devices for managing each of the groups; an exchange switch for exchanging and switching these plurality of bus control devices; and a plurality of communication control processing devices connected in parallel to each group to form a group in each communication control processing device. A fault detection device in a data communication switching system including a central control processing device that performs fault detection and fault processing in the system including the fault described above, wherein the fault detection device is mounted in the data communication switching system by a notification from the central control processing device. Management means for recognizing and managing all communication control processing devices, and the data obtained by the management means. Transmission path state determination means for determining a transmission path state between the communication control processing apparatuses by an operation of transmitting test data between communication control processing apparatuses mounted in the communication switching system, and transmission path state determination means. And a device state analyzing means for comprehensively judging a transmission path state in each communication control processing device. 2. A data communication switching system provided with the fault detecting device, wherein the communication control processing device is modularized for each predetermined component, and is connected to a bus in a fixed unit to exchange these components. 2. The failure detection device in a data communication switching system according to claim 1, wherein the failure detection device is a bus distributed processing type data communication switching system in which a plurality of communication control processes are decentralized by being connected to each other via a switch. 3. The fault in the data communication switching system according to claim 1, wherein said transmission path state determination means is provided for each communication control processing device of said plurality of communication control processing devices. Detection device. 4. A plurality of communication control processors each of which executes a predetermined communication control processing operation, and a plurality of predetermined number of communication control processors connected to one bus as one group of a predetermined number. A plurality of bus control devices for managing each of the groups; an exchange switch for exchanging and switching these plurality of bus control devices; and a plurality of communication control processing devices connected in parallel to each group to form a group in each communication control processing device. A fault detection method in a data communication switching system including a central control processing unit that performs fault detection and fault processing in the system including a fault in the system, wherein the communication control processing unit tests a transmission line pattern to be tested in advance. A first step of transmitting data, and the test data is normally transmitted based on the test data transmitted in the first step. A second step in which each of the communication control processing devices determines whether or not a communication has been received; and, if it is determined in the second step that the transmission has not been performed normally, the transmission control unit corresponds to the transmission path pattern on which the test was performed. A third step of notifying a test result report from each communication control processing device to the central control processing device; and a specific communication in which a failure has occurred in the central control processing device based on the notification in the third step. And a fourth step of determining a control processing device.