JP2017228934A - Fault detection device and fault detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of detecting an intermittent fault with a simple configuration.SOLUTION: A fault detection device includes: a frame termination unit for extracting information to detect a fault from a received frame signal; a fault monitoring unit for determining if there is an alarm in the frame signal for each frame of the frame signal on the basis of the information; and a counter unit for increasing a count value by one every time it is determined that there is an alarm on the basis of its determination result and decreasing the count value by one every time it is determined that there is not an alarm. The fault monitoring unit outputs a signal to determine that a fault has occurred if the count value reaches a prescribed threshold value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a failure detection device and a failure detection method, and more particularly, to a failure detection device and a failure detection method for detecting an intermittent failure.

  In a communication device that includes multiple communication cards, due to external factors, data is garbled at unspecified locations, causing intermittent failures that temporarily cause data errors in communication between communication cards. There is. External factors that cause data errors include, for example, radiation and electromagnetic waves that are applied to circuit elements from the outside. When such a data error occurs, usually, relief is performed by error detection correction processing and retransmission processing each time.

  However, intermittent failures occur repeatedly depending on the degree, and the effect appears in the form of device performance degradation and connection line quality degradation. If the intermittent failure is left as it is, the intermittent failure may eventually shift to a fixed failure. If so, there is a possibility that the influence of the failure may reach the entire communication system connected to the communication device. A fixed failure is a failure that occurs not fixed intermittently but fixed in time, that is, continuously.

  Fixed failures due to internal factors such as cable disconnection, electronic component deterioration failure or sudden failure are often detected as fixed failures in the apparatus. Such a fixed failure is relatively easy to identify the suspicious part. However, since the occurrence of intermittent failures is difficult to notice, it often takes time to identify the location of failure and the cause of failure.

  For example, frame synchronization may be employed as a signal synchronization method between a plurality of communication cards arranged in a communication device. In general, forward protection is set as a detection threshold value for a frame synchronization failure between communication cards, and backward protection is set as a threshold value after failure detection until recovery. Forward protection and backward protection suppress the occurrence of faults and recovery notifications that are overly sensitive.

  In general forward protection, failure detection is triggered when the number of consecutive frames from the frame synchronization state until the frame synchronization pattern matching result detects P consecutive inconsistencies reaches the alarm generation threshold (= the number of forward protection stages). Is done. In general backward protection, a failure occurs when the number of consecutive frames from the out-of-frame synchronization state until the frame synchronization pattern matching result detects Q consecutive matches reaches the alarm stop threshold (= the number of backward protection stages). Recovery is reported. P and Q are natural numbers and are defined by the specifications of the communication card in which frame synchronization is used.

  In relation to the present invention, Patent Document 1 discloses a technique for detecting an intermittent failure. Patent Document 2 discloses a data transmission apparatus having different counts for normal word down-counting and error word up-counting.

JP2012-080426A Japanese Examined Patent Publication No. 58-040383

  Both the number of front protection steps and the number of rear protection steps are cumulative values obtained by continuous counting. Therefore, for example, if the frame synchronization pattern is determined to be normal even for one frame before reaching the number of forward protection stages due to an intermittent failure in the apparatus, the cumulative value by the continuous count becomes “0” (zero). Cleared. In this case, since the cumulative count value is cleared to 0 before reaching the number of forward protection stages, an intermittent failure is not issued.

  When out-of-frame synchronization is detected, it is notified as severely errored second (SES) or non-available second (UAS) by a performance monitor (PM) provided in the communication system. There is a case. However, when an intermittent failure that is not recognized as out-of-frame synchronization as described above has occurred, the PM does not notify the intermittent failure as a failure, so a general PM cannot detect the intermittent failure.

  In the threshold crossing alert (TCA), the number of BIP (Bit Interleaved Parity) calculation results exceeding the threshold is counted, for example, at intervals of 15 minutes or 24 hours. However, if signal loss and loss of frame synchronization are detected, the TCA count is stopped. For this reason, even if an intermittent failure that is not recognized as out of frame synchronization occurs, the intermittent failure may not be known from the TCA count.

  As described above, a general communication device using a frame signal has a problem that an intermittent failure may not be recognized. On the other hand, since the invention described in Patent Document 1 uses a health check packet for detecting intermittent failures, a transmission / reception circuit for the health check packet is necessary. When the invention of Patent Document 1 is applied to a communication device, There exists a subject that the structure of a communication apparatus becomes complicated. Patent Document 2 does not mention a technique for detecting an intermittent failure.

(Object of invention)
An object of this invention is to provide the technique which can detect an intermittent failure with a simple structure.

  The failure detection apparatus of the present invention includes a frame termination unit that extracts information for detecting a failure from a received frame signal, and determines whether there is an alarm in the frame signal for each frame of the frame signal based on the information. And a counter means for accumulating a count value every time it is determined that there is an alarm based on a result of the determination, and subtracting the count value every time it is determined that there is no alarm. And the failure monitoring means outputs a signal for determining that a failure has occurred when the count value reaches a predetermined threshold value.

  The failure detection method of the present invention extracts information for detecting a failure from a received frame signal, and determines the presence or absence of an alarm in the frame signal for each frame of the frame signal based on the information. The count value is accumulated every time it is determined that there is an alarm based on the result of the above, and the count value is subtracted every time it is determined that there is no alarm, and if the count value reaches a predetermined threshold value, a failure occurs. A signal for determining occurrence is output.

  The fault detection program of the present invention is a procedure for extracting information for detecting a fault from a received frame signal to a computer of the fault detection apparatus, and based on the information, the presence or absence of an alarm of the frame signal is detected. A procedure for determining each frame, a procedure for accumulating a count value every time it is determined that there is an alarm based on a result of the determination, and a step for subtracting the count value every time it is determined that there is no alarm, the count value Includes a procedure for executing a procedure for outputting a signal for determining that a failure has occurred when the value reaches a predetermined threshold value.

  The fault detection apparatus and fault detection method of the present invention can detect intermittent faults with a simple configuration.

1 is a block diagram illustrating a configuration example of a communication system 100 and a line interface device 1 according to a first embodiment. It is a figure which shows the example of the frame format of the frame signal in an apparatus. FIG. 10 is a diagram illustrating an example of transition of the count number of an UP / DOWN counter circuit 221. 4 is a flowchart illustrating an example of an operation procedure for detecting an intermittent failure in a card 2. It is a block diagram which shows the structural example of the failure detection apparatus 500 of 2nd Embodiment. 5 is a flowchart illustrating an example of an operation procedure of the failure detection apparatus 500.

  Hereinafter, embodiments of the present invention will be described. In each embodiment, detection of intermittent failure in data transmission between communication cards provided in the apparatus will be described.

(First embodiment)
The configuration of the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of the communication system 100 and the line interface device 1 according to the first embodiment. The communication system 100 includes a line interface device 1 and an external device 4.

  The line interface device 1 performs bidirectional data transmission with the external device 4 in response to an external line interface signal. The data transmitted between the line interface device 1 and the external device 4 may be data generated inside each device or data notified from other devices to each device. The transmission medium for the external line interface signal is, for example, an optical cable or a metallic cable, but is not limited thereto. The line interface device 1 and the external device 4 may be connected by wireless communication.

  The line interface device 1 includes a card 2 and a card 3. The cards 2 and 3 are communication cards having a communication function, and are, for example, electric circuits formed on a printed wiring board and having a signal processing function. Each of the card 2 and the card 3 has a function for realizing the function of the line interface device 1. The card 2 includes an intra-device frame termination unit 21, an intra-device fault monitoring unit 22, a data collection unit 23, a fault reporting unit 24, a line interface termination unit 25, and a line fault monitoring unit 26. The card 3 includes an in-device frame termination unit 31, an in-device failure monitoring unit 32, a data collection unit 33, and a failure notification unit 34. Further, the in-device failure monitoring unit 22 includes an UP / DOWN counter circuit 221, and the in-device failure monitoring unit 32 includes an UP / DOWN counter circuit 321.

  The card 2 communicates with the external device 4 using an external line interface signal, and communicates with the card 3 using an in-device frame signal. The line interface termination unit 25 is a transmission / reception interface with the external device 4 and has a function of terminating an external line interface signal. The data collection unit 23 has a function of extracting data required at the output destination from signals input from the in-device frame termination unit 21 and the line interface termination unit 25. The card 2 has a function of monitoring and processing a failure in communication with the external device 4 and a failure in an interface with the external line by the line failure monitoring unit 26.

  The card 3 communicates with the card 2 using the in-device frame signal. The data collection unit 33 has a function of extracting data necessary for the inside of the card 3 or another communication card (not shown) from the signal input from the in-device frame termination unit 31. The data collection unit 33 may have a function of outputting data generated in the card 3 or another communication card (not shown) to the in-device frame termination unit 31.

  The in-device frame termination units 21 and 31 included in the card 2 and the card 3 are transmission / reception interfaces for communication between cards. The in-device frame terminators 21 and 31 transmit the in-device frame signal to the opposite card and terminate the in-device frame signal received from the opposite card. The card 2 and the card 3 are connected by a physical medium such as an optical cable, a metallic cable, or a connector. The in-device frame termination units 21 and 31 include an interface circuit that converts an in-device frame signal from an optical signal to an electric signal, conversion between different types of electric signals, and the like in accordance with the connection form between cards. The in-device frame termination units 21 and 31 may further include a circuit for multiplexing and demultiplexing the frame signal. Such a configuration enables data transmission between the card 2 and the external device 4 and between the card 3 and the external device 4.

  The line interface device 1 detects an intermittent failure in communication between cards by the device failure monitoring unit 22 in the card 2 and the device failure monitoring unit 32 in the card 3. The in-device failure monitoring units 22 and 32 monitor information required for determining the generation of information indicating a failure due to an abnormality in the in-device frame signal. These pieces of information are, for example, a frame synchronization pattern stored in the in-device frame signal, a BIP calculation result, and the like, and are information used to determine whether an alarm is issued. The frame synchronization pattern is a bit string having a pattern and a length defined by the specifications of the line interface device 1. These pieces of information are notified from the in-device frame termination units 21 and 31 to the in-device failure monitoring units 22 and 32, respectively. The in-device failure monitoring units 22 and 32 determine whether or not an abnormality has occurred based on the notified information and accumulate the alarm information.

  When the accumulated alarm information reaches the failure reporting level, the in-device failure monitoring unit 22 notifies the failure reporting unit 24 of the occurrence of the failure. When the failure notification unit 24 is notified of the occurrence of a failure from the in-device failure monitoring unit 22, the failure notification unit 24 reports the occurrence of a failure related to the in-device frame signal to a higher-level device (not shown). Similarly, when the accumulated alarm information reaches the failure notification level, the in-device failure monitoring unit 32 notifies the failure notification unit 34 of the occurrence of the failure. When the failure notification unit 34 is notified of the occurrence of a failure from the device failure monitoring unit 32, the failure notification unit 34 reports the occurrence of a failure related to the device frame signal to a higher-level device (not shown).

  The line failure monitoring unit 26 monitors information required for determining the occurrence of an alarm caused by an abnormality in the external line interface signal. Information regarding the abnormality of the external line interface signal is notified from the line interface termination unit 25 to the line failure monitoring unit 26. The line failure monitoring unit 26 determines whether or not an abnormality has occurred based on the notified information and accumulates it as alarm information. When the accumulated alarm information reaches the failure notification level, the line failure monitoring unit 26 notifies the failure notification unit 24 of the occurrence of the failure. Even when a failure occurrence is notified from the line failure monitoring unit 26, the failure reporting unit 24 reports the occurrence of a failure related to the external line interface signal to a host device (not shown).

  FIG. 2 is a diagram illustrating an example of the frame format of the intra-device frame signal transmitted and received between the card 2 and the card 3. The in-device frame signal is composed of a repetition of a frame having a length of 125 μs (microseconds). Each frame includes payload (data), overhead (OH), and channel overhead (COH). In the OH, for example, various types of information regarding the frame configuration and the like are stored. For example, a frame synchronization pattern and a BIP calculation result are stored in COH. The frame synchronization pattern is used to detect the position of COH, OH and payload of the received frame signal.

  The frame format in FIG. 2 shows an example of the configuration of the frame signal used in this embodiment, and the data lengths of payload, OH, and COH and their specific contents are defined based on the specifications of the cards 2 and 3. Is done. For example, each payload length is 261 bytes, both OH length and COH length are 9 bytes, and 9 payloads of 261 bytes, 8 9-byte OHs, and 1 9-byte COH in 125 μs May be transmitted. In this case, the transmission rate of the in-device frame signal is 155.52 Mbps (megabits per second), and the payload transmission capacity is 150.336 Mbps. Of course, these numerical values are examples, and the frame format of the embodiment is not limited.

(Description of operation of the first embodiment)
The operation of the line interface device 1 of the first embodiment will be described with reference to the drawings. The card 2 receives the in-device frame signal illustrated in FIG. 2 from the card 3 and terminates the received in-device frame signal in the in-device frame termination unit 21. The in-device failure monitoring unit 22 is notified of information used to determine the occurrence of an alarm stored in either the OH or COH of the in-device frame signal input from the in-device frame termination unit 21, The failure monitoring unit 22 monitors these pieces of information. As will be described later, in the present embodiment, a case will be described in which the frame synchronization pattern stored in the COH is notified from the in-device frame termination unit 21 to the in-device failure monitoring unit 22.

  The UP / DOWN counter circuit 221 in the in-device failure monitoring unit 22 is a counter circuit that counts up or down a numerical value. The UP / DOWN counter circuit 221 counts up or down according to whether or not the frame signal is abnormal. When the in-device frame termination unit 31, the in-device fault monitoring unit 32, and the UP / DOWN counter circuit 221 of the card 3 receive the in-device frame signal from the card 2, the in-device frame termination unit 21, the in-device fault monitoring unit 22, and It operates in the same manner as the UP / DOWN counter circuit 321. For this reason, the detailed description regarding operation | movement of the card | curd 3 is abbreviate | omitted.

  In the present embodiment, as an example, a case will be described in which the frame synchronization pattern is stored in the COH, and the in-device failure monitoring unit 22 monitors the presence or absence of an alarm due to an abnormality in the frame synchronization pattern. The in-device frame termination unit 21 outputs the frame synchronization pattern stored in the COH to the in-device failure monitoring unit 22 every frame (125 μs). The in-device failure monitoring unit 22 monitors the frame synchronization pattern input from the in-device frame termination unit 21, determines that there is an alarm if the frame synchronization pattern is abnormal, and sets the alarm bit to “1”. To do. If the frame synchronization pattern is normal, it is determined that there is no alarm, and the alarm bit is set to “0” (zero).

  The in-device failure monitoring unit 22 checks the normality of the frame synchronization pattern as described above every time the frame synchronization pattern is notified from the in-device frame termination unit 21. That is, the in-device failure monitoring unit 22 determines “no alarm” when the notified frame synchronization pattern matches the prescribed frame synchronization pattern. Further, the in-device failure monitoring unit 22 determines that “alarm is present” when the notified frame synchronization pattern is incorrect even in one bit. However, other criteria may be used to determine “with / without alarm”.

  The alarm bit is, for example, a 1-bit variable stored in the in-device failure monitoring unit 22. The UP / DOWN counter circuit 221 performs the following operation for each frame based on the value of the alarm bit (that is, the presence or absence of an alarm).

  (1) When there is an alarm (alarm bit = “1”), the count value is incremented by M.

  (2) When there is no alarm (alarm bit = “0”), the count value is counted down by N.

  Here, M and N are natural numbers defined in advance by the specifications of the line interface device 1. The count value is accumulated in the UP / DOWN counter circuit 221, and the accumulated count value is represented by T below. The cumulative count value T is not cleared to “0” even when the alarm bit is “0” (that is, when the notified frame synchronization pattern is normal).

  When the cumulative count value T of the UP / DOWN counter circuit 221 reaches the failure detection threshold T0 as a result of the count-up and count-down according to the procedures (1) and (2) above, the in-device failure monitoring unit 22 detects the occurrence of a failure. The failure notification unit 24 is notified. Upon receiving the notification, the failure notification unit 24 notifies the host device of the occurrence of the failure. When the cumulative count value T of the UP / DOWN counter circuit 221 reaches the failure recovery threshold value T1, the in-device failure monitoring unit 22 notifies the failure reporting unit 24 of the failure recovery. Upon receiving the notification, the failure notification unit 24 notifies the host device of the failure recovery. Here, T0 and T1 are predetermined threshold values, and T0> T1.

  In the frame synchronization pattern inspection procedure described above, the alarm detection rate D in the UP / DOWN counter circuit 221 can be defined as D = M / (M + N). The alarm detection rate D is an index indicating the increase rate of the accumulated count value in the UP / DOWN counter circuit 221. When the alarm detection rate D is increased, the increase amount of the cumulative count value T of the UP / DOWN counter circuit 221 can be increased even if the ratio of the “alarm exists” state (that is, the occurrence probability) does not change, and as a result It can be detected earlier.

  Here, the value of the alarm detection rate D can be increased by weighting the count-up value M for “with alarm” and the count-down value N for “without alarm” to be different values. For example, the relationship between the count-up value M when an alarm is detected and the count-down value N when no alarm is detected may be M> N. By setting M> N, the increase in the accumulated count value due to the count-up due to the detection of one “alarm” can be superior to the count-down due to the detection of “no alarm” once.

  Note that the failure reporting condition (the number of forward protection stages, that is, the number of consecutive frames until the frame synchronization pattern matching result is detected in the frame synchronization state) remains the same as the specification for detecting out-of-frame synchronization within the device. It is good. However, if the count-up value M for one “alarm is present” is increased, the protection time until the in-device failure monitoring unit 22 notifies the failure reporting unit 24 of the failure detection is shortened (ie, forward protection). (The number of steps becomes smaller.) For this reason, in the present embodiment, the count-up value M at the time of alarm detection is increased, and at the same time, the failure detection threshold T0 is increased at the same ratio as the count-up value M. For example, consider a case where the length of one frame of the in-device frame signal is 125 μs and the number of forward protection stages is 224. In this case, the failure detection threshold is 125 μs × 224 frames = 28 ms.

  Here, in the present embodiment, it is assumed that the count-up value M = 4 and the count-down value N = 1. That is, M: N is 4: 1. In this case, if the alarm occurrence rate for each frame exceeds 1/5 (= 20%) within the period in which the frame synchronization pattern is monitored, the expected count-up amount is greater than the expected count-down amount. Is also big. Therefore, on average, the count-up prevails over the count-down, so that even an intermittent failure can be detected as a failure. More generally, in general, M / N> (1-A) / A, where A is the alarm occurrence rate and 1-A is the ratio when there is no alarm. It can be expressed that intermittent failure can be detected by setting M and N to. In the above example, A = 0.2, M = 4, and N = 1. “Alarm occurrence rate” is a ratio when it is determined that there is an alarm. Also, 0 <A <1.

  Also, by setting the failure detection threshold T0 to a value four times, the protection time under failure detection can be kept at 28 ms (that is, the number of forward protected frames is 224). That is, since the number of forward protection stages in the time required to determine failure detection at the shortest (failure detection threshold 28 ms) is 224 stages, the cumulative count value T reaching the number of forward protection stages is 224 stages × 4 times = 896 stages. Become. That is, the failure detection threshold T0 is 896 counts.

  Further, when the failure recovery threshold T1 that is the cumulative count value when notifying the recovery of the failure to the host device is “0” count, it is determined that the failure is recovered when the cumulative count value T becomes “0”. Since the time until it is determined to be restored is decreased by 1 count from 896 counts, the shortest time is 112 ms as shown in the following formula 1.

896 (counts) × 125 (μs) = 112 (ms) (Formula 1)
In the above example, when the failure detection threshold T0 is not increased based on the count-up value M, the failure detection threshold T0 is 224 counts. In this case, since 224 ÷ 4 = 56, after the failure recovery (accumulated count value T = 0), the accumulated count value T reaches the failure detection threshold value T0 by 56 “alarms”, so the failure detection threshold value T0. As compared with the case of setting 896 count, intermittent failure can be detected at an early stage.

  FIG. 3 is a diagram illustrating an example of the transition of the count number of the UP / DOWN counter circuit 221. FIG. 3 shows an example of how the count number of the UP / DOWN counter circuit 221 changes based on the above-described contents. The vertical axis in FIG. 3 is the cumulative count value T, and the horizontal axis is time. Since the alarm bit is confirmed every frame of the in-device frame signal, the time advances in units of 125 μs. Then, the UP / DOWN counter circuit 221 performs a count UP / DOWN operation every 125 μs.

  It is assumed that the accumulated count value T of the UP / DOWN counter circuit 221 is 0 in the initial state. When the alarm bit is “1”, the cumulative count value is increased by 4 (for example, the cumulative count value T = 0 → 4 → 8 → 12 in FIG. 3), and when the alarm bit is “0”, the cumulative count value is increased. Decreases by 1 (for example, T = 12 → 11 → 10 in FIG. 3). When the cumulative count value T reaches the fault detection threshold T0 (896 in this embodiment) while repeating the increase / decrease of the cumulative count value in this way, the in-device fault monitoring unit 22 notifies the fault reporting unit 24 of the occurrence of the fault. Notice. Further, after the cumulative count value T reaches the failure detection threshold value T0, when the cumulative count value T decreases to the failure recovery threshold value T1 (T1 = 0 in the present embodiment), the in-device failure monitoring unit 22 24 is notified of failure recovery.

  Depending on the set values of M and N, the cumulative count value T may be negative. In such a case, it may be determined that the failure has been recovered by assuming that T = 0 when T <0. On the other hand, also when the cumulative count value T exceeds the failure detection threshold T0, the in-device failure monitoring unit 22 may determine that a failure has occurred. When the cumulative count value T becomes T ≧ T0, the count-up may be stopped. In the case of “no alarm”, the cumulative count value is counted down by one. When the accumulated count value T is equal to or less than the failure recovery threshold T1, it is determined that the failure is recovered. In the example described above, the failure recovery threshold T1 is set to 0, but it is not always necessary to set T1 = 0. The cumulative count value T may not be cleared to T = 0 after the failure recovery is determined. In this case, the count operation is continued from T = T1, and when “alarm is present”, the cumulative count value T is counted up again by M.

  FIG. 4 is a flowchart showing an example of an intermittent failure detection operation procedure in the card 2. The intra-device frame termination unit 21 extracts information for detecting a failure from the received frame signal, that is, a frame synchronization pattern (step S11 in FIG. 4), and based on the extracted information, an error in the frame synchronization pattern is detected. Presence / absence is determined for each frame (step S12). As a result of the determination, if it is determined that there is an abnormality (“alarm present”), the cumulative count value is incremented by M (step S13), and if it is determined that there is no abnormality (“no alarm”), the cumulative count value is N. Countdown is performed (step S14). Then, it is determined whether or not the cumulative count value has reached the failure detection threshold value T0 or the failure recovery threshold value T1 (step S15). When the cumulative count value T reaches T0 or more (T ≧ T0), the in-device failure monitoring unit 22 notifies the failure reporting unit 24 of the occurrence of the failure (step S16). When the cumulative count value T has decreased to T1 or less (T ≦ T1), the in-device failure monitoring unit 22 notifies the failure reporting unit 24 of failure recovery (step S17).

  The line interface device 1 according to the first embodiment described above has the following effects. That is, the line interface device 1 can detect an intermittent failure in communication using a frame signal, which is difficult to detect by PM (performance monitor) or TCA (threshold excess alert), with a simple configuration. The reason is that the line interface device 1 determines the presence / absence of an alarm based on the frame synchronization pattern extracted from the received frame signal, and detects the occurrence of the failure by the accumulated count value in the UP / DOWN counter circuit 221. is there. The line interface device 1 does not need to generate a health check signal.

  Further, the line interface device 1 can change the failure detection sensitivity. The reason is that, in the UP / DOWN counter circuit 221, the count-up value M when the alarm is generated and the count-down value N when the alarm is not generated are set independently so that the weights of these values are variable. Because.

  As described above, the line interface device 1 according to the first embodiment has an effect that an intermittent failure can be detected with a simple configuration. Since it becomes easy to detect an intermittent failure in the opposing communication card, the failure can be detected early, and the influence on the operation service due to the failure is suppressed.

(Modification of the first embodiment)
The line interface apparatus 1 also has an effect that an intermittent failure can be detected with a simple configuration even by the following modification of the first embodiment.

  In the first embodiment, the procedure for detecting an intermittent failure of the in-device frame signal received from the card 3 in the card 2 has been described. As shown in FIG. 1, the card 3 has the same function as the card 2 for monitoring the in-device frame signal. Therefore, the line interface device 1 may detect an intermittent failure of the in-device frame signal received by the card 3.

  Further, when the line interface device 1 further includes another communication card, the intermittent failure detection procedure described above may be applied to all the interfaces of the in-device frame signals included in each card. With such a configuration, it is possible to detect intermittent failures between opposing communication cards. In addition, since the configuration for fault monitoring provided in the communication card is shared, the manufacturing cost of the communication card can be reduced. In addition, when communication using the in-device frame signal is performed at a plurality of locations in the line interface device 1 and it is desired to increase the detection rate of intermittent failure at a specific location, the count-up value M and the count-down in the communication at that location The ratio of the value N may be adjusted.

  Furthermore, not only an interface between communication cards in the apparatus but also an interface with an external line is used in combination with a failure detection condition based on an official standard such as ITU-T recommendation, and the intermittent failure of the first embodiment. A detection method may be applied. In this case, intermittent failure can be detected also at the interface with the external line. ITU-T is an abbreviation for International Telecommunication Union Telecommunication Standardization Sector.

  Further, in communication cards using parts with a higher failure rate than other communication cards, the weights of the count-up value M and the count-down value N, the failure detection threshold T0, and the failure recovery threshold T1 are set to other communication cards. And may be different. By doing in this way, it becomes easier to detect the intermittent failure of a communication card with a high failure rate, and a more stable operation of a device on which the communication card is mounted becomes possible.

  In the present embodiment, the case where the alarm information is information based on the mismatch of the frame synchronization pattern (that is, loss of frame synchronization) has been described. However, in practice, there are a plurality of pieces of alarm information of inter-device frame signals, and by monitoring a plurality of alarm information at the same time, it is possible to detect intermittent faults for a plurality of alarm information included in the in-device frame signal.

  The card 2 may further include a central processing unit (CPU) and a recording medium. The functions and operation procedures of the line interface device 1 may be realized by the CPU executing a program recorded on the recording medium. The program is recorded on a fixed, non-temporary recording medium. As the recording medium, a semiconductor memory or a fixed magnetic disk device is used, but is not limited thereto.

(Second Embodiment)
FIG. 5 is a block diagram illustrating a configuration example of the failure detection apparatus 500 according to the second embodiment of this invention. The failure detection apparatus 500 includes a frame termination unit 501, a failure monitoring unit 502, and a counter unit 503.

  The frame termination unit 501 receives a frame signal and extracts information for detecting a failure from the received frame signal. The failure monitoring unit 502 determines, for each frame signal frame, whether there is an alarm in the frame signal, based on information extracted from the frame signal for detecting a failure. The determination of the presence or absence of an alarm in the frame signal is performed, for example, by setting “alarm present” when information for detecting a failure is normal and “no alarm” when the information is incorrect. Also good.

  The counter unit 503 is provided in the failure monitoring unit 502. The counter unit 503 accumulates the count value every time it is determined that “alarm exists” based on the determination result of the presence or absence of an alarm, and subtracts the count value every time it is determined that “no alarm”. As a result of the accumulation of the count values, when the count value of the counter unit 503 increases and becomes equal to the predetermined first threshold value, the failure monitoring unit 502 outputs a signal indicating the occurrence of the failure. As a result of the subtraction of the count value, when the count value of the counter unit 503 decreases and becomes equal to the predetermined second threshold, the failure monitoring unit 502 outputs a signal indicating failure recovery. Here, the first threshold value is larger than the second threshold value.

  FIG. 6 is a flowchart illustrating an example of an operation procedure of the failure detection apparatus 500. The failure detection apparatus 500 extracts information for detecting a failure from the received frame signal (step S51 in FIG. 6), and based on the extracted information, the presence / absence of an alarm in the frame signal is determined for each frame signal frame. Judgment is made (step S52). As a result of the determination, if it is determined that there is an alarm, the count value is accumulated (step S53), and if it is determined that there is no alarm, the count value is subtracted (step S54). Then, it is determined whether or not the count value has reached at least one of a predetermined first threshold value and a second threshold value (step S55). If the count value reaches the first threshold as a result of the accumulation of the count value, the failure detection device 500 outputs a signal for determining that a failure has occurred (step S56). If the count value reaches the second threshold value as a result of the subtraction of the count value, the failure detection device 500 outputs a signal for determining failure recovery (step S57).

  The failure detection apparatus 500 having such a configuration has an effect that an intermittent failure can be detected with a simple configuration. The reason is that information for detecting the failure is extracted from the received frame signal, and the failure is detected by the counter unit 503 based on the accumulated count value.

  The in-device frame termination unit 21, the in-device failure monitoring unit 22, and the UP / DOWN counter circuit 221 of the line interface device 1 according to the first embodiment are each a frame termination unit included in the failure detection device 500 according to the second embodiment. 501, a function corresponding to the failure monitoring unit 502 and the counter unit 503 is provided. That is, the line interface device 1 of the first embodiment also has the same function as the failure detection device 500 of the second embodiment. The failure detection threshold T0 and the failure recovery threshold T1 of the first embodiment correspond to the first threshold and the second threshold of the second embodiment, respectively.

  Similar to the line interface device 1 of the first embodiment, the failure detection device 500 may further include a CPU and a recording medium. The functions and operation procedures of the failure detection apparatus 500 may be realized by the CPU executing a program recorded on the recording medium. The program is recorded on a fixed, non-temporary recording medium. As the recording medium, a semiconductor memory or a fixed magnetic disk device is used, but is not limited thereto.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  Further, the configurations described in the respective embodiments are not necessarily mutually exclusive. The operation and effect of the present invention may be realized by a configuration in which all or part of the above-described embodiments are combined.

1 Line interface device 2, 3 card 4 External device 21, 31 Intra-device frame termination unit 22, 32 In-device fault monitoring unit 23, 33 Data collection unit 24, 34 Fault reporting unit 25 Line interface termination unit 26 Line fault monitoring unit DESCRIPTION OF SYMBOLS 100 Communication system 221,321 UP / DOWN counter circuit 500 Fault detection apparatus 501 Frame termination part 502 Fault monitoring part 503 Counter part

Claims (10)

Frame termination means for extracting information for detecting a failure from the received frame signal;
Fault monitoring means for determining the presence or absence of an alarm of the frame signal for each frame of the frame signal based on the information;
A counter means for accumulating a count value every time it is determined that there is an alarm based on a result of the determination, and subtracting the count value every time it is determined that there is no alarm;
The failure monitoring unit is a failure detection device that outputs a signal that determines that a failure has occurred when the count value reaches a predetermined threshold value.   Assuming that the count value accumulated when it is determined that there is the alarm is M, and the count value that is subtracted when it is determined that there is no alarm is N, M and N are natural numbers and M> The failure detection apparatus according to claim 1, wherein N is N.   M / N> (1-A, where A is the ratio when it is determined that there is an alarm and 1-A (where 0 <A <1) is the ratio when it is determined that there is no alarm. 3) The fault detection apparatus according to claim 2, wherein M and N are set to be equal to / A. A line interface device comprising a first communication card and a second communication card,
The first communication card is
A line interface termination means that is an interface with an external device;
The failure detection device according to any one of claims 1 to 3, which receives a frame signal from the second communication card;
A data collection means for transmitting and receiving data between the line interface termination means and the failure detection device;
The second communication card includes other frame termination means for transmitting and receiving the frame signal to and from the first communication card.
Line interface device. The second communication card includes the failure detection device according to any one of claims 1 to 3 instead of the other frame termination unit.
The line interface device according to claim 4. A line interface device according to claim 4 or 5,
An external device that communicates with the line interface device using an external line interface signal;
A communication system comprising: Extract information to detect a failure from the received frame signal,
Based on the information, the presence or absence of an alarm of the frame signal is determined for each frame of the frame signal,
Based on the result of the determination, the count value is accumulated every time it is determined that there is an alarm, and the count value is subtracted every time it is determined that there is no alarm,
When the count value reaches a predetermined threshold, a signal that determines that a failure has occurred is output.
Fault detection method.   Assuming that the count value accumulated when it is determined that there is the alarm is M, and the count value that is subtracted when it is determined that there is no alarm is N, M and N are natural numbers and M> The failure detection method according to claim 7, wherein N is N.   M / N> (1-A, where A is the ratio when it is determined that there is an alarm and 1-A (where 0 <A <1) is the ratio when it is determined that there is no alarm. 9) The failure detection method according to claim 8, wherein M and N are set to be / A. In the computer of the fault detection device,
A procedure for extracting information for detecting a failure from the received frame signal,
A procedure for determining the presence or absence of an alarm in the frame signal for each frame of the frame signal based on the information;
A procedure for accumulating the count value every time it is determined that there is an alarm based on the result of the determination, and subtracting the count value every time it is determined that there is no alarm;
A procedure for outputting a signal for determining that a failure has occurred when the count value reaches a predetermined threshold;
Fault detection program for executing

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