JP2004356794A - Optical transmission apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmission apparatus capable of estimating a fault location in a short period of time on the occurrence of a fault even in the case of optical transmission of one to multi connection or multi to multi connection. <P>SOLUTION: The optical transmission apparatus includes: an optical branching unit 55 for branching a data signal transmitted from a CPU board 1 and transmitting the branched signals respectively to memory boards 1 to 3; and an optical coupler for coupling the data signals transmitted respectively from the memory boards 1 to 3 and transmitting the coupled signal to the CPU board 1, transmits the data signal from the CPU board 1 to the memory boards 1 to 3 to write the data signal to memories mounted on the memory boards 1 to 3 and estimates a fault location on the basis of error information of the data signal obtained in the process of receiving the data signals read from each memory by the CPU board 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical transmission device capable of specifically estimating a failure location when a failure occurs.
[0002]
[Prior art]
Conventionally, optical fibers have been used mainly for backbone communications, taking advantage of their characteristics, but the signal transmission method using them is based on transmission in which the transmitting side and the receiving side are connected one-to-one. I have.
[0003]
On the other hand, with the recent development of very large scale integrated circuits (VLSI), circuit functions of circuit boards used in data processing systems have been greatly increased. Further, as circuit functions have increased, the number of signal lines used on each circuit board has also increased, and the number of core wires of cables connecting between the boards has also increased. In such a system, in a conventional transmission method using electric wires, reflection due to mismatching of the characteristic impedance of the cable, signal delay due to variations in the length of the electric wires, or radiated electromagnetic field noise due to unnecessary radiation from the electric wires. However, these have been obstacles to speeding up the signal.
[0004]
As a means for solving this kind of problem, there is a method using optical transmission. If optical fibers are used in optical transmission, it is possible to increase the speed of signals without generating radiated electromagnetic field noise due to unnecessary radiation, and it is also possible to reduce the number of optical fibers by serializing the signals. is there. For the reasons described above, the application of optical fibers to signal transmission between devices, within devices, or between chips on a board is gradually progressing not only for basic communication applications.
[0005]
For example, in an image forming apparatus, the amount of image data developed for high image quality and high-speed output tends to increase year by year, and processors have been improved and the operating frequency has been increasing. . Here, control signals, image data, and the like handled by the image forming apparatus are not necessarily processed in one substrate, but are transmitted and processed between substrates having each function via some transmission medium. There are cases. In this type of device, although the transmission technology, parts and materials have been improved, when the transmission speed exceeds several tens of MHz, image data etc. can not be transmitted electrically easily at present. is there. As transmission speeds increase in the future, electrical transmission will become more difficult, and cable length will be limited for accurate transmission. A technique using an optical transmission medium such as an optical fiber has been reported for such a problem. The optical transmission medium has the following advantages.
a) Since there is no restriction on the length of the cable, the control board and the like can be laid out freely.
b) The frequency band is wide, and is hardly affected by the contact state of the connector.
c) No radiation noise.
[0006]
When considering such an application, if the connection method of the optical fibers is limited to one-to-one, the use range is not widened, and therefore, one-to-many, or one-to-many in order to join (coupling) or split (branch) the signal light. Many-to-many connection methods are required. At that time, an optical branching / coupling device (optical branching device and / or optical coupling device) is used to connect the optical fibers one-to-many or many-to-many. For this, for example, a component such as an optical star coupler is used, but an optical sheet bus as described in Patent Document 1 can also be used.
[Patent Document 1]
JP 10-123350 A
On the other hand, when a failure occurs in the optical transmission device, it is necessary to report the error information to a predetermined device to facilitate the maintenance of the optical transmission device. Therefore, for example, Patent Literature 2 describes an error processing method when a failure occurs in an optical receiving unit.
[Patent Document 2]
Japanese Patent Application Laid-Open No. H2-56658 discloses an error detection unit that determines whether a failure that has occurred in an optical receiving unit is one that hinders recognition of a command from a higher-level device. If so, the control unit is configured to report the error information to the higher-level device by the transmission unit, whereby the error information is reported to the higher-level device, and a quick countermeasure can be taken. .
[0008]
[Problems to be solved by the invention]
By the way, in an optical transmission device used between boards or the like, for example, when transmitting a control signal of a processor by an optical signal, there are many control signals common to each board such as an address bus and a data bus. And an optical branching / coupling device such as an optical sheet bus. In an optical transmission device using this type of optical branching / coupling device, when a failure occurs, the connection between the substrates is one-to-many or many-to-many, so it is difficult to determine where the failure is. When error information is reported from a device equipped with a memory or the like to a processor by optical transmission, a failure may have occurred in the transmission medium itself that transmits the error information. It will be difficult. In the error processing method described in Patent Document 2, it is possible to determine an error in one-to-one connection optical transmission, but it cannot be applied to such one-to-many connection or many-to-many connection optical transmission. There is a problem.
[0009]
Therefore, an object of the present invention is to provide an optical transmission device that can estimate a failure location in a short time when a failure occurs even in one-to-many connection or many-to-many connection optical transmission.
[0010]
[Means for Solving the Problems]
An object of the present invention is to provide a first device equipped with a processor, a plurality of second devices equipped with a memory, and a data signal transmitted from the first device branched to the plurality of second devices respectively. An optical transmission device comprising: an optical branching device for transmitting, and an optical coupling device for coupling data signals respectively transmitted from the plurality of second devices and transmitting the data signal to the first device. Transmitting a data signal from the device to the plurality of second devices, writing the data signal to the memory of the plurality of second devices, and transmitting the data signal read from the memory to the first device. This is achieved by an optical transmission device that estimates a failure location based on error information of the data signal obtained in a receiving process.
[0011]
Here, the error information may include the presence or absence of an error in the data signal transmitted from the first device, the presence or absence of an error in the data signal received by the first device, and the transmission from the first device. The presence of an error due to a mismatch between the data signal obtained and the data signal received by the first device may be included. The presence or absence of an error in the data signal transmitted from the first device and the presence or absence of an error in the data signal received by the first device are respectively detected by an error correction code added to the data signal. Can be. In addition, the optical transmission device can include an error information table that stores the presence or absence of each of the errors. The estimated failure location can be notified to a higher-level device.
[0012]
The failure diagnosis method for an optical transmission device according to the present invention includes transmitting a data signal from a first device equipped with a processor to a plurality of second devices equipped with a memory via an optical branching device. The data signal is written to the memory of the device, and the data signal read from the memory is received by the first device via an optical coupling device, and the data signal transmitted from the first device is received by the first device. The presence or absence of an error, the presence or absence of an error in the data signal received by the first device, and the mismatch between the data signal transmitted from the first device and the data signal received by the first device The failure location is estimated based on the presence or absence of an error. Here, the transmission of the data signal from the first device to the plurality of second devices can be sequentially performed to the plurality of second devices.
With this configuration, even in the case of one-to-many connection or many-to-many connection optical transmission, when a failure occurs, a failure location can be specifically estimated in a short time.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. Before that, a configuration example of an optical transmission device to which the present invention is applied will be described.
FIG. 1 is a diagram illustrating a configuration example of an optical transmission device. A CPU (Central Processing Unit) used for controlling an operation of a mechanical system or an ASIC (Application Specific IC) for image processing, includes a CPU and peripheral devices (ASIC, memory, etc.). There is a CPU bus, also called a CPU interface, for electrically connecting and controlling. When the bidirectional data bus of the CPU bus is to be realized by an optical fiber connection, it is necessary to divide the optical signal system into two systems, a transmitting side and a receiving side, as shown in FIG.
[0014]
As shown in FIG. 1, the optical transmission device of the present embodiment includes a master device 1 (hereinafter, referred to as a CPU board) and a plurality of slave devices 2 to 4 (hereinafter, memory boards 1-3). The CPU board 1 has a CPU (processor) 11, a digital ASIC 12, an optical transmitter 13, and an optical receiver 14. The optical transmitter 13 includes a light emitting element 131 such as one or a plurality of laser diodes (LD), a driving circuit 132 thereof, and an optical connector 133 for coupling to an optical fiber. The optical receiver 14 has a light receiving element 141 such as one or a plurality of photodiodes (PD), a receiving circuit 142, and an optical connector 143 for coupling to an optical fiber. The ASIC 12 is provided with a predetermined clock 15.
[0015]
The memory boards-1 to 3 can have the same configuration, and have memories 21, 31, 41, digital ASICs 22, 32, 42, optical transmitters 23, 33, 43, and optical receivers 24, 34, 44, respectively. . As in the case of the CPU board, the optical transmitters 23, 33, and 43 include one or a plurality of light emitting elements such as laser diodes (LDs), their driving circuits, and optical connectors 233, 333 for coupling to optical fibers. 433. Similarly, the optical receivers 24, 34, and 44 include one or more light receiving elements such as photodiodes (PD), a receiving circuit, and optical connectors 243, 343, and 443 for coupling to an optical fiber. As a variation, an ASIC or a general-purpose IC may be provided in place of the memories 21, 31, and 41. As the memory, a temporary memory in the processor can be used without separately providing a RAM (Random Access Memory).
[0016]
The downstream optical transmission line 5 and the upstream optical transmission line 6 are connected between the CPU board 1 and the memory boards-1 to 3. The downstream optical transmission line 5 has an optical fiber A, an optical branching device 55, and a plurality of optical fibers BD. The upstream optical transmission line 6 has an optical fiber E, an optical coupling device 65, and a plurality of optical fibers F to H. As shown in FIG. 1, the optical fiber A is connected to the optical connector 133, and the optical fibers BD are connected to the optical connectors 243, 343, and 443. The optical fiber E is connected to the optical connector 143, and the optical fibers F to H are connected to the optical connectors 233, 333, and 433. Here, as the optical fiber, for example, a plastic optical fiber (POF) can be used, but it is not limited to this. As the optical branching device 55 and the optical coupling device 65, for example, an optical star coupler or an optical sheet bus provided with a transmitted light diffusing unit (JP-A-10-123350, JP-A-10-282371, etc.) may be used. it can. Power is supplied to the CPU board 1 and the memory boards-1 to 3 from a power supply device (not shown).
[0017]
FIG. 2 is a diagram showing an example of a signal flow in the optical transmission device of FIG. This figure shows a case of 10 downlink channels (D0 to D8, CLK) and 5 uplink channels (D'0 to D'3, CLK). When writing data from the CPU board 1, which is a board on which a CPU (processor) is mounted, to the memory boards 1-3, which are boards on which an ASIC, a memory, and the like are mounted, an address AD, data Each control signal such as DA, write WR, and chip select CS and other signals OT such as an error correction code and a frame clock (CLK) are transmitted from the optical transmitter via the optical transmission line 5. The memory boards-1 to 3 receive these signals by the optical receiver. When reading data from the memory boards-1 to 3, the CPU board 1 first transmits signals such as an address AD, a read RE, and a chip select CS from the CPU board 1 from the optical transmitter via the optical transmission line 5. Each of the memory boards 1 to 3 performs an operation according to a signal received by each optical receiver. Then, the memory boards-1 to 3 send signals such as data DA and error correction code CO to the CPU board 1 from the optical transmitter via the optical transmission line 6. In this example, no return frame clock (CLK ') signal is sent. The CPU board 1 can receive the data signal and the like by the optical receiver and receive the data.
[0018]
When transmitting an optical signal from the CPU board 1 to the memory board via the optical branching device 55, unlike the case of transmission by one-to-one connection, the optical signal from the CPU board 1 is transmitted to all of the memory boards 1-3. Will be sent to This is because the signal branched by the optical branching device 55 reaches each memory board. Therefore, the receiving side of each memory board determines whether the signal is related to itself, and as a result, if the signal is transmitted to itself, receives that signal; otherwise, ignores it. A determination device for performing the determination. To make this determination, a unique identification number is stored in each memory board. This identification number can be assigned to each memory board from the CPU board.
[0019]
The optical signal is usually converted into a serial signal and transmitted. However, since the optical signal is considered to have lower reliability than an electric signal, an error correction code (ECC: Error Correction Code) is generally used instead of a data signal. It may be generated, added to the data signal and transmitted. The receiving side determines at any time from the received data signal and the error correction code whether an error (error) has occurred in the data signal. If an error (error) has occurred in the data signal, the erroneous data signal is corrected, and the data signal is transferred to the subsequent stage. If the error cannot be corrected (error), error information is notified to an external circuit as a transmission error.
[0020]
In the present invention, when a failure occurs in the optical transmission device, a self-diagnosis sequence is provided for specifically estimating a failure location in a short time, and a data signal is transmitted from the CPU board 1 to the memory boards 1-3. A failure point is estimated based on error information of a data signal obtained in a process of writing a data signal to a memory mounted on the memory boards-1 to 3 and receiving a data signal read from each memory by the CPU board 1. . As will be described later, this error information includes the presence or absence of an error in the data signal transmitted from the CPU board 1, the presence or absence of an error in the data signal received by the CPU board 1, and the data signal transmitted from the CPU board 1 and the CPU. It includes the presence / absence of an error due to the mismatch of the data signals received by the board 1. The presence or absence of an error in each data signal can be detected by an error correction code added to the data signal.
[0021]
The means for executing the self-diagnosis sequence can be provided as hardware or software in the CPU board 1. In this example, this software is stored in a memory (not shown) provided in the CPU board 1, and the CPU 11 executes the self-diagnosis sequence using this software. presume. The inferred failure point can be notified to the host device.
[0022]
Immediately after the power is turned on to the system, the CPU board 1 usually starts a self-diagnosis sequence in order to check whether or not a failure has occurred in the circuit. This self-diagnosis sequence may be performed at regular intervals or at each event in some cases.
[0023]
FIGS. 3A and 3B are flowcharts showing a self-diagnosis sequence in one embodiment of the optical transmission device according to the present invention. First, as shown in FIG. 3A, for the memory board-N to which the data signal is transmitted from the CPU board 1, N = 0 is set in step 71, and the memory boards are subjected to the self-diagnosis sequence one by one. At 72, N = N + 1 is set. Next, in step 73, the CPU board 1 writes arbitrary data to the memory of the memory board-N. The memory board-N checks whether a transmission error has occurred based on the received data signal and the error correction code signal, and corrects the data signal if a transmission error has occurred. When the data signal can be corrected, the memory board-N notifies the CPU board 1 as error information when the data signal can be corrected.
[0024]
In step 74, the CPU board 1 determines whether or not the error information has been received from the memory board-N. If the error information cannot be received, in step 75, the error information is stored in the error information table (error in transmission / reception). Is recorded, and the process proceeds to the confirmation of the next memory board-N in step 87 described later. On the other hand, when the CPU board 1 can receive the error information from the memory board-N, in step 76, it detects the presence or absence of an error by using an error correction code (ECC). If there is an error, the CPU board 1 determines in step 77 whether the data signal has been corrected by the error correction code. If not, in step 78, the CPU board 1 stores the error information (memory board) in the error information table. -N transmission cannot be corrected), and the process proceeds to step 87, which will be described later, to confirm the next memory board -N. On the other hand, when the data signal can be corrected by the error correction code in step 77, the CPU board 1 records error information (data correction has occurred in the memory board-N transmission) in the error information table in step 79. .
[0025]
Next, if no error is detected by the ECC (data is normal) in step 76, and if the data signal can be corrected in step 77, the CPU board 1 reads data from the memory of the memory board-N in step 80. Read the signal. Then, in step 81, the CPU board 1 detects the presence or absence of an error in the read data signal by using an error correction code (ECC). If there is an error, the CPU board 1 determines in step 82 whether the data signal could be corrected by the error correction code. If not, in step 83, the CPU board 1 stores the error information (memory board) in the error information table. -N reception cannot be corrected), and the process proceeds to the confirmation of the next memory board -N in step 87 described later. On the other hand, when the data signal can be corrected by the error correction code in step 82, the CPU board 1 records error information (data correction has occurred in the memory board-N reception) in the error information table in step 84. .
[0026]
In step 81, if no error is detected by ECC (data is normal) in step 81, and if the data signal is corrected in step 82, the data written in the memory of the memory board-N is read in step 85. The signal is compared with the data signal read therefrom to determine whether it is the same data signal. If the two data signals do not match, the CPU board 1 records the error information (write / read error of the memory board-N) in the error information table in step 86, and the next memory board in step 87 described later. Move to confirmation of -N.
If the two data signals compared in step 85 are the same, the CPU board 1 proceeds to step 87 to check the next memory board-N and repeats the above sequence. When the confirmation of all the memory boards-N is completed, the self-diagnosis sequence ends.
[0027]
FIG. 4 is a diagram showing an example of an error information table obtained by executing a self-diagnosis sequence in the optical transmission device according to the present invention. With this error information table, it is possible to specifically estimate a component having a high possibility of failure. Hereinafter, cases (1) to (8) shown in FIG. 4 will be described.
[0028]
Case (1): Since all of the memory boards-1 to 3 are marked with a circle and normal writing / reading has been performed in each memory, it is presumed that there is no failure.
Case (2): Regarding the memory board-1, since it is not possible to perform normal writing / reading on the memory, it is marked with a cross. Then, the detection status of the presence or absence of an error by the error correction code is examined. If there is an error in the downstream (transmission) of the optical transmission line, it is assumed that a failure has occurred in the CPU board, the memory board-1, or the downstream B of the optical transmission line, which is marked with a cross in the figure. If there is an error in the upstream (reception) of the optical transmission line, a failure in the CPU board, the memory board-1, or the upstream F of the optical transmission line is estimated. When there is no error, a failure in the memory board-1 is assumed.
[0029]
Case (3): Regarding the memory board-2, it is not possible to perform normal writing / reading to / from the memory, so that the mark is marked “X”. Then, the detection status of the presence or absence of an error by the error correction code is examined. If there is an error in the downstream (transmission) of the optical transmission path, it is assumed that a failure has occurred in the CPU board, the memory board-2 or the downstream C of the optical transmission path marked with a cross. If there is an error in the upstream (reception) of the optical transmission path, a failure in the CPU board, the memory board-2, or the upstream G of the optical transmission path is estimated. When there is no error, a failure in the memory board-2 is assumed.
Case {circle around (4)}: For the memory boards-1 and 2, normal writing / reading to / from the relevant memory cannot be performed, so that the mark is marked with x. Then, the detection status of the presence or absence of an error by the error correction code is examined. If there is an error at the downstream (transmission) of the optical transmission line, it is assumed that a failure occurs in the optical branching device marked with a cross. If there is an error in the upstream (reception) of the optical transmission line, a failure in the optical coupling device is presumed. If there is no error, a failure in the CPU board and the memory boards-1 and 2 is assumed.
[0030]
Case (5): Regarding the memory board-3, it is not possible to perform normal writing / reading to / from the memory, so that the mark is marked "X". Then, the detection status of the presence or absence of an error by the error correction code is examined. If there is an error at the downstream (transmission) of the optical transmission line, a failure at the CPU board, the memory board-3 or the downstream D of the optical transmission line marked with a cross is presumed. If there is an error in the upstream (reception) of the optical transmission line, a failure in the CPU board, the memory board-3, or the upstream H of the optical transmission line is estimated. If there is no error, a failure in the memory board-3 is assumed.
Case (6): Regarding the memory boards-1 and 3, this is marked with x because normal writing / reading cannot be performed on the memory. Then, the detection status of the presence or absence of an error by the error correction code is examined. If there is an error at the downstream (transmission) of the optical transmission line, it is assumed that a failure occurs in the optical branching device marked with a cross. If there is an error in the upstream (reception) of the optical transmission line, a failure in the optical coupling device is presumed. When there is no error, a failure in the CPU board and the memory boards-1 and 3 is estimated.
[0031]
Case (7): Regarding the memory boards -2 and 3, normal writing / reading to / from the memory is not possible, so the mark is marked with "x". Then, the detection status of the presence or absence of an error by the error correction code is examined. If there is an error at the downstream (transmission) of the optical transmission line, it is assumed that a failure occurs in the optical branching device marked with a cross. If there is an error in the upstream (reception) of the optical transmission line, a failure in the optical coupling device is presumed. When there is no error, a failure in the CPU board and the memory boards -2 and 3 is estimated.
Case (8): Regarding all of the memory boards-1 to 3, normal writing / reading to each memory cannot be performed, so that the mark is marked with x. Then, the detection status of the presence or absence of an error by the error correction code is examined. If there is an error in the downstream (transmission) of the optical transmission line, it is assumed that a failure has occurred in the CPU board, the downstream A in the optical transmission line, or the optical branching device marked with a cross. If there is an error in the upstream (reception) of the optical transmission line, a failure in the CPU board, the upstream E of the optical transmission line, or the optical coupling device is presumed. If there is no error, a failure in the CPU board is presumed.
[0032]
In estimating the failure location, consider the error detection by the memory board and the error correction code and the transmission path of the optical sheet bus one-to-many or many-to-one, and consider a location that is linked to the error result and has a high possibility. Is assumed to be a failure. In the determination based on the data signal and the error correction code signal, for example, when an electrical defect occurs in the memory board, there is a high possibility that the data read by the CPU board 1 will cause an error no matter how many times the data is read. When a trouble gradually occurs in the optical transmission path, the data signal read by the CPU board 1 may repeat correct / incorrect. The failure location is estimated based on these. By notifying the host device of such information, it is possible to reduce the time required to find a fault location, and as a result, to reduce the downtime of the system.
[0033]
【The invention's effect】
According to the present invention, even in one-to-many connection or many-to-many connection optical transmission, it is possible to obtain an optical transmission device that can estimate a failure location in a short time when a failure occurs.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of an optical transmission device.
FIG. 2 is a diagram illustrating an example of a signal flow in the optical transmission device of FIG. 1;
FIGS. 3A and 3B are flowcharts showing a self-diagnosis sequence in one embodiment of the optical transmission device according to the present invention.
FIG. 4 is a diagram showing an example of an error information table obtained by executing a self-diagnosis sequence in the optical transmission device according to the present invention.
[Explanation of symbols]
1 CPU board 2-4 Memory board 1-3
5 Downlink optical transmission line 6 Uplink optical transmission line 11 CPU
12, 22, 32, 42 ASIC
13, 23, 33, 43 Optical transmitters 14, 24, 34, 44 Optical receiver 55 Optical branching device 65 Optical coupling device

Claims (7)

A first device equipped with a processor, a plurality of second devices equipped with a memory, and an optical branch for branching a data signal transmitted from the first device and transmitting the data signal to each of the plurality of second devices An optical transmission device comprising: a device; and an optical coupling device that combines the data signals respectively transmitted from the plurality of second devices and transmits the combined data signal to the first device. Transmitting a data signal to a plurality of second devices, writing the data signal to the memory of the plurality of second devices, and receiving the data signal read from the memory by the first device; An optical transmission device, wherein a failure location is estimated based on the obtained error information of the data signal. The error information may include an error in the data signal transmitted from the first device, an error in the data signal received by the first device, and the error transmitted from the first device. The optical transmission device according to claim 1, further comprising an error caused by a mismatch between the data signal and the data signal received by the first device. The presence or absence of an error in the data signal transmitted from the first device and the presence or absence of an error in the data signal received by the first device are detected by error correction codes added to the data signal, respectively. 3. The optical transmission device according to claim 2, wherein: 4. The optical transmission device according to claim 2, further comprising an error information table for storing presence / absence of each of the errors. The optical transmission device according to any one of claims 1 to 4, wherein the estimated failure location is notified to a higher-level device. Transmitting a data signal from a first device equipped with a processor to a plurality of second devices equipped with a memory via an optical branching device, writing the data signal to the memory of the plurality of second devices, and The data signal read from the memory is received by the first device via the optical coupling device, and the presence or absence of an error in the data signal transmitted from the first device is received by the first device. Estimating a fault location based on the presence or absence of an error in the data signal and the presence or absence of an error due to a mismatch between the data signal transmitted from the first device and the data signal received by the first device. A method for diagnosing a failure of an optical transmission device. 7. The optical transmission device according to claim 6, wherein the transmission of the data signal from the first device to the plurality of second devices is sequentially performed to the plurality of second devices. Diagnostic method.

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