JP2013157856A - Uninterruptible switching device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid contention due to a phase difference between writing timing to a buffer memory and reading timing from the buffer memory upon system changeover to enable autonomous restoration of a device failure due to a data error.SOLUTION: An uninterruptible switching device includes an operation system device and a reserve system device. When an error detecting circuit detects an error in a window in a predetermined period, a synchronous control circuit in the operation system changed over from the reserve system after system changeover sets timing of a read reset signal again.

Description

  The present invention relates to an uninterruptible switching device and method.

  Redundant transmission lines (for example, optical fiber transmission lines) and devices (for example, devices (stations) for transmitting / receiving signals (data) to / from the transmission lines), etc. A configuration is adopted in which the operation can be continued by switching to a standby system device in the event of a device failure. In addition, in order to prevent data loss at the time of system switching from the active system apparatus to the standby system apparatus, for example, the reliability of the call / communication service is ensured by implementing a non-instantaneous switching function.

  First, a typical example (reference example) of a non-instantaneous switching memory access control circuit will be described with reference to FIG. In FIG. 8, the active system device 31 (standby system device 32) includes a BIP-8 (Bit Interleaved Parity) insertion circuit 19 (25), a write control circuit 20 (26), an uninterruptible buffer memory 21 (27), and a synchronization. A control circuit 22 (28), a read control circuit 23 (29), and an error detection circuit 24 (30) are provided.

  The BIP-8 insertion circuit 19 (25) performs BIP-8 calculation for each frame on the input data (parallel highway data), stores the calculation result at a predetermined position of the frame, and the uninterruptible buffer memory 21 Data to be written in (27) is generated.

  The write control circuit 20 (26) performs synchronization monitoring on the multiframe number extracted from the input data, generates a synchronization establishment signal and a multiframe pulse (MFP) for each z frame (z is a predetermined positive integer), and This is notified to the synchronous control circuit 22 (28) of the system and the other system. The write control circuit 20 (26) also writes a write reset signal (initial write memory address) to the uninterruptible buffer memory 21 (27) every p frames (p is a predetermined positive integer) based on the extracted multiframe number. The frame data generated by the BIP-8 insertion circuit 19 (25) is written into the uninterruptible buffer memory 21 (27).

  The synchronization control circuit 22 (28) selects and reads the multi-frame pulse of the system whose synchronization is established first from the synchronization establishment signal and the multi-frame pulse from the write control circuit 20 (26) of the own system and the other system. A control signal is generated, and the read control signal is sent to the read control circuit 23 (29).

  The read control circuit 23 (29) performs a read reset for each p frame in accordance with the MF (multi-frame) counter value (0 to z) generated based on the read control signal received from the synchronization control circuit 22 (28). A signal (read memory address initialization signal) is generated, and data is read from the uninterruptible buffer memory 21 (27).

  The uninterruptible buffer memory 21 (27) is a memory having a capacity capable of storing p frames or more, and the uninterruptible buffer memory 21 (27) every time a write reset signal is issued from the write control circuit 20 (26). ), The data is written in order from the write start address, and each time a read reset signal is issued from the read control circuit 23 (29), the data is read in order from the read start address of the uninterruptible buffer memory 21 (27). 1 buffer (FIFO: First In First Out).

  The error detection circuit 24 (30) performs BIP-8 calculation for each frame on the data read from the uninterruptible buffer memory 21 (27), and compares it with the BIP-8 value stored in the frame. To check the normality of the frame data.

  The write control circuits 20 and 26 of the active device and the standby device extract the multiframe number from the input data received by the active device and the standby device, respectively, and write reset timing to the uninterruptible buffer memories 21 and 27 The synchronization control circuits 22 and 28 of the active system and the standby system synchronize the memory read reset timing between the active system and the standby system, and read reset timing to the uninterruptible buffer memories 21 and 27. Are switched at the same timing in the active system and the standby system without interruption.

  For example, Patent Documents 1 and 2 are known as non-instantaneous switching circuits. Patent Document 1 discloses a configuration in which a memory is shared between an active system and a standby system. In Patent Document 1, a frame / multiframe synchronization detection unit synchronizes multiframes in units of 64 frames, a frame buffer holds data for a period of time until an error is detected, and a write determination unit stores write data and a write address Referring to the status bit and the value of the status bit written to the address of the memory unit of the corresponding address, the write determination to the memory unit is made, and the address comparison unit compares the write address of the active system and the standby system A read phase is generated based on the address of the slow system. Further, in Patent Document 2, the active system and the standby system apparatus include an MF (multiframe) synchronization circuit, a phase comparison circuit, a FIFO, a memory read circuit, a write / read phase comparison, an insertion / extraction detection unit, and an operation state monitoring unit, The structure provided with the uninterruptible switching part is disclosed.

JP 2000-013346 A Japanese Patent No. 3389062

  Reference examples and analysis of related technologies are given below.

  In the uninterruptible switching device, as shown as a reference example in FIG. 8, the timing of the write reset to the uninterruptible buffer memory 21 (27) between the active device and the standby device is the write control circuit 20 (26). In FIG. 4, the active system device and the standby system device are generated at individual timings. Also, in order to normally perform non-instantaneous switching from the active system to the standby system, the timing of read reset to the uninterruptible buffer memory 21 (27) is determined by the synchronous control circuit 22 (28) by the active system and the standby system. Synchronized between devices.

  Further, once the state is confirmed and the operation state is entered, the timings of the write reset signal and the read reset signal are not re-synchronized until the synchronization is lost between the active system and the standby system.

  Therefore, when the system is switched between the active system and the standby system (the standby system is the new active system and the active system is the new standby system), the following problems may occur.

  Even if the system is switched between the active system and the standby system, the timing of read reset to the uninterruptible buffer memory does not change, so the transmission path between the active system and the standby system by changing the transmission path ( When the line length difference (mainly optical fiber) becomes large, the timing of write reset to the uninterruptible buffer memory 21 (27) is shifted. If the system is switched in this state, the timing of the write reset to the uninterruptible buffer memory changes. As a result, the positional relationship between the write reset timing and the read reset timing with respect to the uninterruptible buffer memory in the new operation system device may be outside the regulation of the phase difference between them in the steady state.

  In such a case, the frame data write access and read access to the uninterruptible buffer memory compete. As a result, the BIP-8 error is detected by the error detection circuit 24 (30) for the frame data read from the uninterruptible buffer memory, resulting in a hardware failure state (details are compared with the embodiment of the present invention). An example will be described later with reference to FIG. 5).

Also, the cause of hardware failure due to BIP-8 error is
・ Is there a BIP-8 error due to a memory failure in the non-instantaneous buffer memory?
-The positional relationship between the write reset timing and the read reset timing is out of regulation due to the phase difference between the active system and the standby system, and a BIP-8 error occurs due to contention access to the uninterruptible buffer memory. Or
There is also a problem that they cannot be distinguished.

  For this reason, there is a case where a memory failure due to a contention between access to the uninterruptible buffer memory and a read access is determined as a hardware failure even though it is not actually a memory failure. Furthermore, the above-described state (that is, the state of hardware failure due to BIP-8 error detection caused by write and read access contention) continues until recovery from a hardware failure. As a result, communication services and the like are impaired.

  In the configuration of Patent Document 1, when the phase difference between writing and reading to the uninterruptible buffer memory becomes out of regulation, the readjustment is automatically performed (if the writing phase is later than the reading phase). The read phase is automatically determined by re-phase matching). However, every time the frame position fluctuates due to transmission path jitter or the like, readjustment (instantaneous interruption) occurs every time.

  In Patent Document 2, as a method for resetting the read reset signal when switching to the standby system when the phase difference between reading and writing is out of the specified range (outside the allowable range of uninterrupted switching), -The read phase comparison circuit constantly monitors whether the phase difference of the write reset signal from the read reset signal is within the allowable range, and each time the phase difference is outside the allowable range, the phase timing of the read reset signal is determined. The value is reset to a desired value. In this case, every time phase adjustment is performed, a temporary failure (read frame abnormality) such as a temporary discontinuity occurs. Also, if the phase of the read reset signal is automatically adjusted during system switching, if an error occurs when reading the uninterruptible buffer memory, it may be due to a read timing error or an error due to a real memory failure (hardware failure) It becomes impossible to distinguish whether there is.

  The present invention was devised in view of the above problems, and its purpose is to avoid contention due to the phase difference between the write and read timings to the buffer memory at the time of system switching, and to prevent failures due to data errors. Therefore, an object is to provide an uninterruptible switching device and method that can be recovered autonomously.

According to the present invention, each of the active system device and the standby system device extracts a multiframe number from the received input data and generates a write reset signal to the buffer memory;
A synchronization control circuit that generates a read control signal by selecting a multi-frame pulse of a system whose synchronization is first established from a synchronization establishment signal and a multi-frame pulse from the own system and another system,
A read control circuit for generating a read reset signal to the buffer memory for each predetermined number of frames determined in advance based on the read control signal received from the synchronization control circuit;
An error detection circuit that performs an operation for calculating inspection information on the data read from the buffer memory and detects an error in the data in comparison with the inspection information stored in the frame;
In the synchronous control circuit of the apparatus newly switched from the standby system to the active system after system switching, if an error is detected by the error detection circuit within a predetermined predetermined window, the buffer memory There is provided an uninterruptible switching device that performs control for resetting the timing of the read reset signal.

According to the present invention, the processing executed by each of the active device and the standby device is:
A write control step of extracting a multi-frame number from the received input data and generating a write reset signal to the buffer memory;
A synchronization control step of generating a read control signal by selecting a multi-frame pulse of a system whose synchronization is first established from the synchronization establishment signal and the multi-frame pulse from the own system and another system;
A read control step for generating a read reset signal to the buffer memory for each predetermined number of frames based on the read control signal;
An error detection step of calculating inspection information for data read from the buffer memory and detecting an error in the data by comparing with inspection information stored in a frame;
Including
In the apparatus that is newly switched from the standby system to the active system after the system switching, if an error is detected in the error detection process within a predetermined period of time in the synchronization control process, the buffer memory is stored. An uninterruptible switching method for resetting the timing of the read reset signal is provided.

  According to the present invention, at the time of system switching, contention due to the phase difference between the write and read timings to the buffer memory is avoided, and autonomous recovery is possible against a device failure due to a data error.

It is a figure which shows the structure of the 1st exemplary embodiment of this invention. It is a figure which shows the structure of the synchronous control part of the 1st exemplary embodiment of this invention. It is a figure explaining the operation example of the 1st exemplary embodiment of this invention. It is a figure explaining the operation example of the 1st exemplary embodiment of this invention. It is a figure explaining the operation example of a comparative example. It is a figure explaining the operation example of the 1st exemplary embodiment of this invention. It is a figure which shows the structure of the synchronous control part of the 2nd exemplary embodiment of this invention. It is a figure which shows the structure of a reference example.

  Preferred embodiments and embodiments of the present invention will be described below. According to a preferred embodiment of the present invention, the synchronization control circuit of the apparatus that is switched from the standby system to the active system after the system switchover determines the timing of the read reset signal when an error is detected by the error detection circuit within the window for a predetermined period. The configuration is to be reset. More specifically, each of the active system device and the standby system device (13, 14 in FIG. 1) extracts the multiframe number from the received input data, and sets the write reset timing to the buffer memory (3, 9 in FIG. 1). From the write control circuit to be generated (2, 8 in FIG. 1), the synchronization establishment signal and the multiframe pulse from the own system and the other system, the multiframe pulse of the system that has been established first is selected, and the read control signal is selected. A synchronization control circuit (4, 10 in FIG. 1) that generates and notifies the read control circuit (5, 11 in FIG. 1), and the read control signal received from the synchronization control circuit (4, 10 in FIG. 1). As a reference, a read control circuit (5 and 11 in FIG. 1) for generating a read reset timing of the buffer memory (3 and 9 in FIG. 1) for each predetermined frame, and the buffer memory (3 and 9 in FIG. 1). 9) The data read out from the data is calculated for each frame and compared with the data inspection information stored in the frame. If the values do not match, it is determined that there is an error, and the synchronization control circuit (FIG. 1 and 4), and an error detection circuit (6, 12 in FIG. 1), and the synchronous control circuit (in FIG. 1) of the apparatus switched from the standby system to the active system after system switching. 4, 10) resets the timing of the read reset signal when an error is detected by the error detection circuit (6, 12 in FIG. 1) within a window of a predetermined period.

  According to a preferred embodiment of the present invention, the write control circuit (2, 8 in FIG. 1) performs synchronization monitoring on a multiframe number extracted from input data, and establishes a synchronization establishment signal and a multiframe pulse for every predetermined number of frames. 1 and notify the synchronous control circuits (4 and 10 in FIG. 1) of the own system and the other system, and write reset signals to the buffer memory for each predetermined number of frames based on the multiframe number. Generate.

  According to a preferred embodiment of the present invention, the synchronization control circuit (4, 10 in FIG. 1) is configured to detect the multiframe of the system that has been synchronized first from the synchronization establishment signal and the multiframe pulse from the own system and the other system. A pulse is selected, a read control signal is generated, and the read control circuit (5, 11 in FIG. 1) is notified. The read control circuit (5, 11 in FIG. 1) is configured to determine a predetermined frame according to a multiframe counter value generated based on the read control signal received from the synchronization control circuit (4, 10 in FIG. 1). Each time a read reset signal is generated, data is read from the buffer memory (3, 9 in FIG. 1). According to a preferred embodiment of the present invention, when the write reset signal is issued, the buffer memory (3, 9 in FIG. 1) writes data sequentially from the write head address, and the read reset signal is issued. Then, data is read sequentially from the read head address. The error detection circuit (6, 12 in FIG. 1) performs inspection information calculation for each frame on the data read from the buffer memory (3, 9 in FIG. 1), and is stored in the frame. If the values do not coincide with each other, the data error is determined and an error signal is notified to the synchronous control circuit (4 and 10 in FIG. 1).

  According to a preferred embodiment of the present invention, in the apparatus switched from the standby system to the active system after system switching, the synchronous control circuit (4, 10 in FIG. 1) generates a window for a predetermined time period, When an error is detected by the error detection circuit, a multi-frame pulse resynchronization instruction is issued to generate the read control signal, and the read control circuit (5, 11 in FIG. 1) The timing of the read reset signal is reset to the buffer memory (3 and 9 in FIG. 1).

  According to a preferred embodiment of the present invention, the synchronization control circuit (4 and 10 in FIG. 2) monitors the synchronization state by the synchronization establishment signal, selects the multiframe pulse of the system that has established synchronization earlier, and selects it. A multi-frame pulse synchronization control unit (MFP synchronization control unit 15 in FIG. 2) that generates a read control signal based on a multi-frame pulse, and a control signal (ACT signal) indicating an active system in an active state and a standby system in an inactive state : A device to which an active ACT signal is input becomes an active system), and after a system switch occurs and the value of the control signal changes to an active state, a predetermined number (s maximum) ) And the error detection circuit (6, 12 in FIG. 1) when the system switching window signal is enabled. When an error signal (BIP-8 error signal) is received, the multiframe pulse synchronization control unit (15 in FIG. 2) is instructed to resynchronize the multiframe pulse, and the window control unit (in FIG. 2). 16), a read reset control unit (RR control unit 17 in FIG. 2) for sending a disable signal is provided.

  According to another preferred embodiment of the present invention, the synchronous control circuit (4 ′, 10 ′ in FIG. 7) detects the error a plurality of times when the system switching window is enabled, and the read reset control unit ( An error detection protection unit (18 in FIG. 7) that notifies the RR control unit 17) of FIG. 7 of an error signal may be provided.

  According to one of the preferred embodiments of the present invention, after system switching, a new operating system device (a device switched from the standby system device to the operating system) is used for BIP-8 in the window control and error detection circuit in the synchronous control circuit. From the error detection monitoring result, it is determined whether or not to reset the read reset signal to the uninterruptible buffer memory. That is, the timing of the read reset signal is reset using the system switching and the BIP-8 error detection in the error detection circuit 12 as triggers.

  Further, when system switching is performed, after the system switching, window control is performed in the synchronous control circuit (4, 10 in FIG. 1), and the error detection circuit detects, for example, a BIP-8 error in the window, The timing of the read reset signal to the uninterruptible buffer memory is changed by the synchronous control circuit and the read control circuit. The window control performed by the synchronous control circuit (4 and 10 in FIG. 1) determines whether the BIP-8 error is due to a memory failure or an error due to memory access contention due to system switching. Used to do.

  With the above configuration, it is possible to avoid the occurrence of contention between reading and writing to the uninterruptible buffer memory in the new operational system after system switching, to eliminate the occurrence of BIP-8 errors, and to generate frames from the uninterruptible buffer memory. At the time of data reading, it is possible to recover autonomously by eliminating the occurrence of the BIP-8 error from the hardware failure due to the detection of the BIP-8 error. After that, the new read reset timing is notified to the newly set up device, and the read reset timing is synchronized again in both systems. Hereinafter, exemplary embodiments will be described.

<Embodiment 1>
FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention. Referring to FIG. 1, in the operational system device 13 (standby system device 14), the BIP-8 insertion circuit 1 (7) performs BIP-8 operation for each frame on the input data (parallel highway data), The calculation result is stored at a predetermined position of the frame, and data to be written to the uninterruptible buffer memory 3 is generated.

  The write control circuit 2 (8) performs synchronization monitoring on the multiframe number (0 to z: z is a predetermined positive integer determined in advance) extracted from the input data, and establishes a synchronization establishment signal and a multiframe pulse for each z frame. (MFP) is generated and notified to the synchronization control circuit 4 (10) of the own system and the other system. Further, based on the extracted multiframe number, a write reset signal (write memory address initialization signal) to the uninterruptible buffer memory 3 (9) every p frames (p is a predetermined positive integer determined in advance). The frame data generated and generated by the BIP-8 insertion circuit 1 is written into the uninterruptible buffer memory 3 (9).

  The synchronization control circuit 4 (10) generates a read control signal by selecting the multi-frame pulse of the first synchronization established system from the synchronization establishment signal and multi-frame pulse from the own system and the other system, and generates a read control signal. 5 (11).

  The read control circuit 5 (11) generates a read reset signal (read memory) for each p frame in accordance with the MF counter value (0 to z) generated based on the read control signal received from the synchronization control circuit 4 (10). Address initialization signal) is generated, and the read is executed to the uninterruptible buffer memory 3 (9).

  The uninterruptible buffer memory 3 (9) is a memory having a capacity capable of storing p frames or more, and every time a write reset signal is issued, data is sequentially written from the write start address of the uninterruptible buffer memory 3 (9). Each time a read reset signal is issued, the buffer (FIFO) reads data sequentially from the read head address of the uninterruptible buffer memory 3 (9).

  The error detection circuit 6 (12) performs BIP-8 calculation for each frame on the frame data read from the uninterruptible buffer memory 3 (9) and compares it with the BIP-8 value stored in the frame. Then, the normality of the frame data is confirmed.

  In the error detection circuit 6 (12), when the BIP-8 calculation result does not match the stored value, it is determined as a BIP-8 error, and a BIP-8 error signal is notified to the synchronization control circuit 4. The same operation is performed in the standby system device 14.

  FIG. 2 is a diagram showing an example of the configuration of the synchronization control circuit 4 (10) of FIG. In FIG. 2, the MFP (multi-frame pulse) synchronization control unit 15 monitors the synchronization state based on the synchronization establishment signal from the write control circuits 2 and 8, selects the multi-frame pulse of the system that has established synchronization earlier, and selects it. A read control signal is generated based on the multi-frame pulse.

  The window control unit 16 monitors the ACT signal, and after system switching occurs and the value of the ACT signal changes (for example, from the standby state (SBY) to the active (ACT) state), the maximum number of s frames (s is a predetermined value) System switching window signal is enabled during (positive integer). A device that inputs an ACT signal (activation signal) that has changed from a standby state (SBY) to an active (ACT) state changes from a standby system to an active system device. A device that inputs an ACT signal (activation signal) in a standby state (SBY) is a standby device.

  Further, when the window control unit 16 does not detect the BIP-8 error between s frames, the window switching window signal is disabled.

  When the system switching window signal is enabled, the RR (Read Reset) control unit 17 receives the BIP-8 error signal output from the error detection circuit 6 (12) of FIG. The MFP is then instructed to resynchronize. In addition, a disable signal is sent to the window control unit 16.

  When receiving the disable signal, the window control unit 16 disables the system switching window signal.

  However, when the RR control unit 17 detects a BIP-8 error signal outside the system switching window, the RR control unit 17 determines that a memory failure has occurred and does not issue a resynchronization instruction to the MFP synchronization control unit 15.

  Upon receiving the MFP resynchronization instruction from the RR control unit 17, the MFP synchronization control unit 15 switches to the selection of the own multiframe pulse and regenerates the read control signal if the other system multiframe pulse has been selected. . Thereby, in the read control circuit 5 (11) of FIG. 1, the MF counter (not shown) is also resynchronized, and the read reset signal is reset.

  Hereinafter, the operation of the present embodiment will be described with reference to time charts shown in FIGS.

  A method for generating the write reset signal (WR) and the read reset signal (RR) will be described with reference to FIG. FIG. 3 shows input data (1 frame = 125 us (u: micro second)), multiframe number MFNo, write reset signal WR, multiframe pulse MFP, multiframe count (MF count), and read reset signal (RR). The transition on the time axis is shown.

  First, a multiframe number (MFNo) is extracted from input data, and when the multiframe number is m, a write reset signal (WR) is generated.

  When the multiframe number is m-1, a multiframe pulse (MFP) is generated, and the MF count (not shown in FIGS. 1 and 2) is set to m in the next frame that receives the multiframe pulse of the selected system. To do.

  Thereafter, the MF count is incremented by 1 every frame (125 us). When the MF count is m + n, a read reset signal (RR) is generated.

  Thereby, the read reset signal (RR) is set after n frames from the write reset signal (WR) of the reference system of the active system and the standby system. Here, the periods of the write reset signal (WR) and the read reset signal (RR) are both a period of p frames (= p × 125 us).

  With reference to FIG. 4, a case where the uninterruptible switching can be normally executed will be described. In FIG. 4, the operational system input data, the operational write reset signal WR, the read reset signal RR, the standby system input data and the standby system write reset signal WR, the read reset signal RR, the operational system read data and the standby system The transition of the read data on the time axis is shown.

  Writes sequentially from the initial address of the non-instantaneous buffer memory based on the write reset signal (WR) at the timing set in each of the active and standby systems, and the read reset signal (RR) common to the active and standby systems Based on the above, reading of the uninterruptible buffer memory (3, 9) is started simultaneously in both systems. Here, when the position of the standby write reset signal (WR) is within the uninterruptible switching range q (us) with respect to the position of the active write reset signal (WR), the standby system switches from the standby system to the standby system. The system can be switched normally.

  Next, with reference to FIG. 5, the case where the uninterruptible switching cannot be normally performed will be described. FIG. 5 shows on the time axis of the active system input data, the active system write reset signal WR, the read reset signal RR, the standby system input data, the standby system write reset signal WR, the read reset signal RR, and the standby system read data. The transition of is shown. FIG. 5 is a comparative example for explaining a case where the uninterruptible switching cannot be normally performed in the configuration of FIG. 8 described as the reference example.

  In FIG. 5, the phase relationship between the frames is greatly shifted between the active system and the standby system, and the position of the standby system light reset signal (WR) is not instantaneously compared to the position of the active system light reset signal (WR). When it is outside the disconnect switchable range q (us) (non-standard), it is transferred from the phase relationship between the write reset signal (WR) and the read reset signal (RR) to the standby uninterruptible buffer memory (27 in FIG. 8). The read processing from the data overtakes the write processing to the uninterruptible buffer memory (27 in FIG. 8) in the middle (the read address to the uninterruptible buffer memory 27 overtakes the writing).

  At this time, the read data (standby read data) from the spare uninterruptible buffer memory (27 in FIG. 8) is broken, and the error detection circuit 30 uses the BIP-8 for confirming the normality of the data. An error occurs (for example, m + p frame data and m frame data are mixed in one frame). Note that the writing process to the uninterruptible buffer memory takes longer time than the reading process.

  When the phase relationship between writing and reading is in such a state, if the system is switched between the active system and the standby system, a BIP-8 error occurs when reading from the uninterruptible buffer memory, and it is determined that a hardware failure has occurred. This hardware failure continues as it is.

  With respect to such a situation, according to the present embodiment described with reference to FIGS. 1 and 2, when the phase difference in write reset timing is large between the active system and the standby system, system switching is performed and no instantaneous interruption occurs. Provided is a configuration that enables recovery (restoration) when a hardware failure occurs due to a BIP-8 error in reading to a buffer memory.

  The operation of the present embodiment shown in FIGS. 1 and 2 will be described with reference to FIG. FIG. 6 shows active system input data, active system write reset signal WR, read reset signal RR, standby system input data and standby system write reset signal WR, read reset signal RR, standby system read data, and synchronization control circuit. The transition (value, waveform) on the time axis of the ACT signal, system switching window, BIP-8 error signal, and MFP resynchronization instruction in (4, 10 in FIG. 2) is shown.

  When the ACT signal changes from the SBY state (not particularly limited, for example, Low level) to the ACT state (High level) by system switching, the window control unit 16 enables the system switching window signal (not particularly limited). For example, High level).

  Next, when the system switching window signal is enabled and a BIP-8 error is detected (although not particularly limited, the BIP-8 error signal transitions from a low level to a high level), the RR control unit 17 The resynchronization instruction signal is activated (not particularly limited, but a high pulse). Upon receiving the activated MFP re-synchronization instruction signal, the MF synchronization control unit 15 resets the read reset signal (RR) at the position (on the time axis) of the self-system write reset signal (WR) + n frame. As a result, the conflict between the writing to the uninterruptible buffer memory and the reading process is eliminated, and the BIP-8 error is also eliminated.

  The system switching window signal is used to distinguish between a BIP-8 error caused by a conflict between writing to the uninterruptible buffer memory and a read process during system switching and a BIP-8 error due to a memory failure.

  If a BIP-8 error occurs when the system switching window signal is disabled (not particularly limited, for example, low level), it is assumed that a memory failure has occurred, and the RR control unit 17 activates the MFP resynchronization instruction signal. The read reset signal is not reset, and a hardware failure occurs.

  As described above, in the present embodiment, in the apparatus having the redundant redundant configuration of the active system and the standby system, if the normal configuration remains as it is, for example, there is a large line length difference between the transmission lines, and the uninterruptible system switching is performed. When the normal operation cannot be performed, the occurrence of the BIP-8 error is eliminated by resetting the read reset signal from the system switching window control triggered by the system switching and the BIP-8 error detection condition. For this reason, it is possible to autonomously recover from a hardware failure state of a BIP-8 error caused by contention between read and write access to the uninterruptible buffer memory due to system switching.

<Embodiment 2>
Next, another exemplary embodiment of the present invention will be described. Although the basic configuration of the present embodiment is the same as that of the first embodiment, the generation and detection of BIP-8 may be configured to use other error detection codes such as CRC (Cyclic Redundancy Check).

  In the present embodiment, the synchronization control circuit 4 '(10') is further devised. FIG. 7 is a diagram illustrating a configuration example of the synchronization control circuit 4 ′ (10 ′) of the present embodiment. Referring to FIG. 7, an error detection protection unit 18 that receives a system switching window from the window control unit 16, receives a BIP-8 error signal, and outputs a BIP-8 error signal to the RR control unit 17 is added. The MF synchronization control unit 15, the window control unit 16, and the RR control unit 17 are the same as those in FIG.

  The error detection protection unit 18 notifies the RR control unit 17 as a BIP-8 error signal when a BIP-8 error is detected a plurality of times while the system switching window is enabled. The error detection protection unit 18 operates only when the system switching window is enabled. When the system switching window is disabled, the error detection protection unit 18 notifies the RR control unit 17 of the BIP-8 error signal even if a BIP-8 error is detected. Do not mask. As a result, erroneous detection of BIP-8 errors due to disturbances in the read reset signal (timing variations) can be prevented, and the accuracy of error detection can be improved.

  It should be noted that the disclosures of the above patent documents are incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. Various disclosed elements (including each element of each claim, each element of each embodiment, each element of each drawing, etc.) can be combined or selected within the scope of the claims of the present invention. . That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea.

1, 7, 19, 25 BIP-8 insertion circuit 2, 8, 20, 26 Write control circuit 3, 9, 21, 27 Uninterruptible buffer memory 4, 4 ', 10, 10', 22, 28 Synchronous control circuit 5, 11, 23, 29 Read control circuit 6, 12, 24, 30 Error detection circuit 13, 31 Operation system device 14, 32 Backup system device 15 MFP synchronization control unit 16 Window control unit 17 RR control unit 18 Error detection protection unit

Claims (10)

Each of the active system and standby system
A write control circuit that extracts a multiframe number from received input data and generates a write reset signal to the buffer memory; and
A synchronization control circuit that generates a read control signal by selecting a multi-frame pulse of a system whose synchronization is first established from a synchronization establishment signal and a multi-frame pulse from the own system and another system,
A read control circuit for generating a read reset signal to the buffer memory for each predetermined number of frames determined in advance based on the read control signal received from the synchronization control circuit;
An error detection circuit that performs an operation for calculating inspection information on the data read from the buffer memory and detects an error in the data in comparison with the inspection information stored in the frame;
With
In the synchronous control circuit of the apparatus newly switched from the standby system to the active system after system switching, when an error is detected by the error detection circuit within a predetermined period of time, the buffer memory is A non-instantaneous switching device characterized by performing control for resetting the timing of a read reset signal. The write control circuit performs synchronization monitoring on the multiframe number extracted from the input data, generates a synchronization establishment signal, and a multiframe pulse for each predetermined number of frames, Notifying the synchronization control circuit of another system, based on the multi-frame number, for each predetermined number of frames, to generate the write reset signal to the buffer memory,
The synchronization control circuit selects a multi-frame pulse of a system that has been previously established from a synchronization establishment signal and a multi-frame pulse from its own system and another system, and generates the read control signal to generate the read control circuit. Notify
The read control circuit generates the read reset signal for each predetermined number of frames according to a multi-frame counter value generated based on the read control signal received from the synchronization control circuit, and Read data from buffer memory,
When the write reset signal is output from the write control circuit, the buffer memory writes data from the head address, and when the read reset signal is output from the read control circuit, the buffer memory reads data from the head address. Go and
The error detection circuit performs an operation for calculating inspection information for each frame of data read from the buffer memory, and compares the calculated inspection information with inspection information stored in the frame. When both values do not match, it is determined as an error, and an error signal is notified to the synchronous control circuit,
In the synchronous control circuit of the device switched from the standby system to the active system after system switching, a window for a predetermined period is generated,
When an error is detected by the error detection circuit within the window, the read control signal is generated by performing a resynchronization instruction of a multi-frame pulse,
2. The uninterruptible switching device according to claim 1, wherein the timing of the read reset signal to the buffer memory is reset via the read control circuit.   Data in which each of the operational system apparatus and the standby system apparatus performs an inspection information calculation operation on the input data for each frame, stores the inspection information at a predetermined position of the frame, and writes it to the buffer memory 3. An uninterruptible switching device according to claim 1, further comprising an inspection information insertion circuit for generating The synchronization control circuit monitors a synchronization state based on the synchronization establishment signal, selects a multiframe pulse of a system that has previously established synchronization, and generates a read control signal based on the selected multiframe pulse. A pulse synchronization controller;
A control signal indicating an active system in an active state and a standby system in an inactive state is monitored, and after a system switchover occurs and the value of the control signal changes to an active state, a predetermined number of frame periods are determined in advance. A window control unit for enabling the system switching window signal during
When an error signal is received from the error detection circuit when the system switching window signal is enabled, the multi-frame pulse resynchronization instruction is issued to the multi-frame pulse synchronization control unit, and the window control unit is instructed. A read reset controller that sends a disable signal to the
The uninterruptible switching device according to claim 2 or 3, characterized by comprising:   The synchronization control circuit includes an error detection protection unit that notifies the read reset control unit of an error signal when an error signal is received from the error detection circuit a plurality of times when the system switching window is enabled. The uninterruptible switching device according to claim 4, further comprising: The processing executed on each of the active device and standby device is
A write control step of extracting a multi-frame number from the received input data and generating a write reset signal to the buffer memory;
A synchronization control step of generating a read control signal by selecting a multi-frame pulse of a system whose synchronization is first established from the synchronization establishment signal and the multi-frame pulse from the own system and another system;
A read control step for generating a read reset signal to the buffer memory for each predetermined number of frames based on the read control signal;
An error detection step of calculating inspection information for data read from the buffer memory and detecting an error in the data by comparing with inspection information stored in a frame;
Including
In the apparatus that is newly switched from the standby system to the active system after the system switching, if an error is detected in the error detection process within a predetermined period of time in the synchronization control process, the buffer memory is stored. And resetting the timing of the read reset signal. The write control step performs synchronization monitoring on the multiframe number extracted from the input data, generates a synchronization establishment signal and a multiframe pulse for each predetermined number of frames, and the local system and the other system Notifying the synchronization control step, based on the multi-frame number, to generate the write reset signal to the buffer memory every predetermined number of frames,
When the write reset signal is issued, the buffer memory continues to write data from the top address,
The synchronization control step selects the multi-frame pulse of the system that has been previously established from the synchronization establishment signal and the multi-frame pulse from its own system and another system, generates the read control signal, and generates the read control signal. Notify
The read control step generates a read reset signal for each predetermined number of frames according to a multiframe counter value generated based on the read control signal received from the synchronization control step, and Read data from memory,
When the read reset signal is issued, the buffer memory reads data from the head address,
The error detection step performs, for each frame, calculation of inspection information for the data read from the buffer memory, and compares the calculated inspection information with the inspection information stored in the frame. In the case where both values do not match, it is determined as an error, and an error signal is notified to the synchronous control process,
After the system switching, in the synchronous control process of the device switched from the standby system to the active system, a window for a predetermined period is generated,
If an error is detected in the error detection step within the window, the read control signal is generated by performing a resynchronization instruction of a multi-frame pulse,
7. The method of switching without interruption according to claim 6, wherein the timing of the read reset signal to the buffer memory is reset through the read control step. Each of the operational system device and the standby system device,
The inspection information is calculated for each frame of the input data, the inspection information is stored at a predetermined position of the frame, and data to be written to the buffer memory is generated. 7. The non-instantaneous switching method according to 7. The synchronization control step includes
A synchronization state is monitored by the synchronization establishment signal, a multiframe pulse of a system that has been previously established in synchronization is selected, and a multiframe pulse synchronization control step that generates the read control signal based on the selected multiframe pulse;
A control signal indicating an active system in an active state and a standby system in an inactive state is monitored, and after a system switchover occurs and the value of the control signal changes to an active state, a predetermined number of frame periods are determined in advance. A window control step for enabling the system switching window signal during
If the error signal is received when the system switching window signal is enabled, the multiframe pulse resynchronization instruction is issued to the multiframe pulse synchronization control step, and the window control step is disabled. A lead reset control process for sending a signal;
The method of switching without interruptions according to claim 6 or 7, characterized by comprising:   In the synchronization control step, when the error signal from the error detection circuit is received a plurality of times when the system switching window is enabled, an error signal is notified to the read reset control step. The non-instantaneous switching method according to claim 9.

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