JP2002111670A - Concentrator/multiplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate analysis of the cause of abnormality in an ATM concentrator/multiplexer by reproducing the state of an input signal on the occurrence of an abnormality. SOLUTION: The concentrator/multiplexer comprises a cell buffer 14 for holding a specified data volume of input signal to an ATM processing section 9 sequentially and holding operation of the cell buffer 14 is stopped based on the occurrence of an abnormality. When the cause of abnormality is analyzed, an input signal is reproduced by reading out data stored in the cell buffer 14 thus realizing a concentrator/multiplexer in which the processing operation can be analyzed easily on the occurrence of abnormality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concentrator / multiplexer in a transmission system using ATM cells.
The present invention relates to a concentrator / multiplexer capable of easily performing a failure analysis related to ATM processing.

[0002]

2. Description of the Related Art In recent years, with the spread of the Internet and the like, the transmission amount of information on a network has been increasing more and more. Further, information to be transmitted is various types of data such as character data, voice, image data, and the like, and a technology for transmitting such multimedia has been developed. Among them, ATM (Asynchronous Transformer) suitable for multiplexing
The transmission system adopting ferMode (asynchronous transfer mode) is increasing. The ATM is a system that has been internationally standardized as a broadband ISDN technology, and has various functions that are excellent not only in the speed of a telecommunication network but also in flexibility.

FIG. 2 is a diagram showing a configuration example of a transmission system using an ATM. The transmission system shown in this figure is a concentrator / multiplexer 2a accommodating a plurality of terminal devices 1a to 1n.
And a concentrator / multiplexer 2b accommodating a plurality of terminal devices 3a to 3n are arranged opposite to each other. The concentrator / multiplexers 2a and 2b are connected by an ATM dedicated line 4, and each of the terminal devices 1a to 3n. 1n and the line concentrator 2a, and between each of the terminal devices 3a-3n and the line concentrator 2b, UTOPIA (U
niversal Test & Operations PHY Interface for ATM)
They are connected by an interface line 5. The UTOPIA interface line 5 is an interface that defines data to be transferred between the ATM layer and the physical layer, and can absorb the diversity of the physical layer and achieve efficient matching.

[0004] This transmission system comprises a concentrator / multiplexer 2a.
Multiplexing devices 2a and 2b multiplex signals from a plurality of terminal devices, respectively, for performing communication between the terminal devices 1a to 1n on the side and the terminal devices 3a to 3n on the line multiplexing device 2b side. The signal is output to the ATM dedicated line 4 and the signal from the ATM dedicated line 4 is demultiplexed (separated) and output to each terminal device. At this time, ATM
FIG. 3 shows a transmission signal form on the dedicated line 4.

FIG. 3 is a diagram showing an example of the form of a transmission signal on the ATM leased line 4, and shows a case where ATM cells are mapped to a secondary group 6M frame. In other words, the 6M frame is a frame composed of 789 bits in a time of 125 μs, of which the last 5 bits are F bits for frame synchronization and error monitoring, and 96 bytes (8 bits × 8 bits) as an area for ATM cell mapping. 96 = 768 bits) and the remaining 2 bytes (8 bits × 2 = 16 bits) are allocated as unused. Then, an ATM cell consisting of 53 bytes is arbitrarily arranged in the ATM cell mapping area. The ATM cell is a 53-byte fixed-length cell in which a payload, which is a 48-byte data block area, is added with a cell header, which is a 5-byte header information area.

In such a transmission system, an ATM is used.
FIG. 4 shows an example of the configuration of a concentrator / multiplexer for multiplexing / demultiplexing cells. FIG. 4 is a diagram illustrating a configuration example of a conventional line multiplexing apparatus. The concentrator / multiplexer 2 shown in FIG. 1 includes a transmission line IF (interface) unit 6 and a frame synchronization unit 7
, A cell synchronization unit 8, an ATM processing unit 9, and a plurality of UTOs.
PIA interface unit 10 and frame generation unit 11
, A transmission path IF 12 and a common control unit 13.
The operation of the concentrator / multiplexer 2 shown in this example will be described for each signal direction. First, the transmission path IF unit 6 receives a multiplexed signal arriving via the ATM leased line 4, and converts the received signal into an electric signal if the received signal is an optical signal, or a code for the transmission path. (AMI, CMI, etc.) signal is converted into a unipolar code signal for use in the device. Next, the frame synchronization unit 7 performs frame synchronization with respect to the output of the transmission line IF 6, and outputs a frame synchronized signal to the cell synchronization unit 8. The cell synchronizer 8 removes the ATM cell from the frame, synchronizes the ATM cell, and then synchronizes the ATM cell.
Output to Then, the ATM processing unit 9 includes the cell synchronization unit 8
Performs predetermined processing based on the ATM protocol and separates and outputs the output according to the destination of each cell. The separated outputs are respectively supplied to a plurality of UTOPIA interface units 10 provided in accordance with the UTOPIA interface lines 5 connected to each terminal device, and the UTOPIA
The interface unit 10 maps the ATM cell to the UTOPIA interface and outputs the ATM cell to the UTOPIA interface line 5.

[0007] As a signal flow in the opposite direction, each UTOPIA interface unit 10 transmits an ATM signal from a UTOPIA interface line 5 corresponding to each terminal device to an ATM.
Cells are extracted and multiplexed by the ATM processing unit 9. The multiplexed ATM cells are arranged in a frame by the frame generation unit 11, and the output from the frame generation unit 11 is output to the ATM dedicated line 4 after the transmission path IF 12 performs the reverse conversion of the transmission path IF 6. The common control unit 13
Is to control these units as a whole.

[0008] In this manner, multiplexing / demultiplexing is performed by the line concentrator / multiplexer 2 corresponding to the ATM, and the transmission order can be flexibly changed according to the data amount and the priority order, so that efficient transmission is possible. It has become.

[0009]

However, the above-described conventional line multiplexing apparatus has the following problems. That is, in the concentrator / multiplexer, A
System abnormalities such as cell loss due to loss of TM cells and the stoppage of the function blocks of the line multiplexing device may occur. When these occur, the line multiplexing device issues an alarm and the abnormality is generated. It can detect what happened. In the case of a cell loss, the receiving terminal of the communication makes a retry request by requesting a retransmission to the transmitting terminal, and in the case of a system abnormality, the concentrator / multiplexer stops functioning. This was addressed by forcibly and automatically resetting the function block where the error occurred. Here, the above-described abnormality alarm may be generated only when a signal input to the concentrator / multiplexer is in a specific state. For example, a case where a specific ATM cell continues even though an ATM cell is normally input, or a case where a specific ATM cell is input.
There is an event that an abnormality is caused by a combination of cells and the like, and even if other ATM cells are input, the abnormality does not occur. In such a case, it is necessary to analyze the concentrator / multiplexer itself in order to identify where the cause is inherent in the concentrator / multiplexer and take measures to prevent the same event from being repeated. However, it was difficult to reproduce and analyze the state of the input signal when the alarm was generated. In other words, in an ATM transmission system in which data is transferred asynchronously, even if the same communication is performed between the same terminal devices as when an alarm occurs, the ATM transmission system is no longer used.
The arrangement order of the cells and the delimitation of the data mounted in those cells are also different. Therefore, there has been a problem that much time is often spent to identify the cause inherent in the concentrator / multiplexer.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is possible to reproduce the state of an input signal when an alarm is generated, so that the cause of the occurrence of an abnormality can be easily analyzed. An object of the present invention is to provide a concentrator / multiplexer.

[0011]

In order to solve the above-mentioned problems, a concentrator / multiplexer according to the present invention is a concentrator / multiplexer disposed between a plurality of non-ATM interface lines and an ATM line. ATM based on protocol
An ATM processing unit for processing cells; a common control unit for controlling the concentrator / multiplexer; a cell buffer for sequentially shifting and storing ATM cells input to the ATM processing unit by a predetermined amount; A storage unit for storing the content stored in the storage unit at every predetermined timing; and a maintenance interface unit for connecting an external device having a function for maintenance. It is characterized in that the state of an input signal when an abnormality occurs can be reproduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. FIG. 1 is a functional block diagram showing an embodiment of a concentrator / multiplexer according to the present invention. Note that functional blocks similar to those shown in FIG. 4 are denoted by the same reference numerals and description thereof will be omitted.

The concentrator / multiplexer 20 shown in FIG.
In addition to the configuration of the conventional concentrator / multiplexer shown in FIG. 1, a cell buffer unit 14 having a memory 15 and a memory control unit 16 is further added.
And a storage unit 17 connected to the cell buffer unit 14 and a maintenance interface unit 18 connected to the common control unit 13. Memory 15 of cell buffer unit 14
Is a memory having a virtually ring-shaped structure, and A
The input signal to the TM processing section 9 is stored so as to be rewritten while always overwriting a predetermined data amount (depending on the memory capacity). Here, the memory capacity of the memory 15 is 64
k bytes, memory 6 for each cell (53 bytes)
Four bytes are used to hold 1024 cell data at all times. In the memory address control in this case, the memory control unit 16 generates an address based on the start position information of the ATM cell determined by the cell synchronization unit 8.

The concentrator / multiplexer 20 shown in FIG. 1 functions as follows. That is, during operation of the concentrator / multiplexer 20, for example, if a cell loss occurs in the ATM processing unit 9, a signal indicating that a cell loss has occurred is output from the ATM processing unit 9 to the common control unit 13, and the common control unit 13 displays an alarm and outputs an alarm signal to the cell buffer unit 14.
This alarm signal is sent to the memory control unit 16 of the cell buffer unit 14.
Is received, the memory control unit 16 controls the write operation of the memory 15 to stop, and the memory 15 stops the write operation. Next, the memory control unit 16
Store the data (1024 ATM cells) held in the storage unit 17 together with the type of the alarm signal. Thus, the storage unit 17 is filed as an input signal when an alarm is generated. When the data transfer to the storage unit 17 is completed, the memory control unit 16 starts the writing operation of the memory 15 again.

The above-described series of operations is the same even when a system abnormality occurs. In this case, the common control unit 13 issues an alarm signal and then sends the function block to the functional block in which the system abnormality has occurred. On the other hand, a reset signal is applied, and the operation is performed so as to immediately recover.

On the other hand, a case in which a cause analysis is performed based on an alarm display generated by the common control unit 13 will be described. First, a maintenance person or the like prepares an analysis device 30 and supplies the analysis device 30 to the maintenance multiplexing device 20 provided with the maintenance device. Interface unit 1
Connect to 8. Then, the concentrator / multiplexer 20 is changed from the operation state to the test state, and the operation is stopped. Next, the analysis device 30 is started, and data communication is performed between the analysis device 30 and the common control unit 13. The common control unit 13 responds to a request from the analysis device 30 by reading the data file group stored in the storage unit 17. The data at the time of the alarm to be analyzed is extracted from the data, and the data is output to the ATM processing unit 9 via the cell buffer 14.
To reproduce the input signal when a desired alarm is generated.

The analysis device 30 includes a concentrator / multiplexer 20.
Has a normal operation database to be performed and a predetermined analysis program, and performs analysis while controlling the line concentrator / multiplexer 20 based on the analysis program. That is, the reproduced input signal is processed in the ATM processing unit 9, and the information of the processing operation is sequentially monitored by the analysis device via the common control unit 13 and the maintenance interface unit 18. The operation stored in the database in advance is compared with the processing operation performed by the ATM processing unit 9 to determine whether the ATM processing unit 9 has performed an erroneous process.

At this time, if the ATM processing unit 9 performs an erroneous process, an alarm such as a cell loss or a system abnormality is generated again by the common control unit 13. It is possible to specifically specify whether an error has occurred in the procedure for performing such processing.
When the cause can be specified in this way, the analysis device 30 transfers the data corresponding to the reproduced input signal from the storage unit 17 to the analysis device 30, and ends the analysis. Then, the analysis device 30
And the concentrator / multiplexer 20 are disconnected, and the concentrator / multiplexer 2 is disconnected.
0 operation is resumed.

In the above-described embodiment of the present invention, an example in which the operation of the concentrator / multiplexer 20 is stopped and the analysis is performed has been described, but if the operation of the concentrator / multiplexer 20 is to be stopped. In the meantime, there arises a problem that communication between the terminal devices across the concentrator / multiplexer 20 cannot be performed. Therefore, a concentrator / multiplexer having the same configuration as the concentrator / multiplexer 20 is separately prepared, and the prepared concentrator / multiplexer performs analysis. For example, the line concentrator / multiplexer 20
A spare (test) line multiplexing device is placed at the manufacturer of the device, and only the data stored in the storage unit 17 of the line multiplexing device 20 in operation is sent to the manufacturer, which is owned by the manufacturer. The analysis is performed by a concentrator / multiplexer of the same type. Specifically, an external recording device is connected to the maintenance interface unit 18 of the concentrator / multiplexer 20, and the data stored in the storage unit 17 is transferred to this external recording device.
The external storage device storing the data may be sent to the manufacturer. Note that a network device may be connected to the maintenance interface unit 18 to send data via the Internet, for example. In this way, without stopping the operation of the line multiplexing device 20, the input signal can be reproduced by the line multiplexing device of the same type owned by the manufacturer.
Can be analyzed.

The form of the ATM transmission system using the concentrator / multiplexer according to the present invention is not limited to the one shown in FIG. 2, but may be, for example, an existing LAN (Local Area Network) instead of the terminal devices 1a to 1n. ) Or, instead of the ATM leased line 4, an ATM network (A
It is needless to say that the line concentrator / multiplexer of the present invention can be applied even to a TM ring system and an ATM switch system.

As described above, the concentrator / multiplexer 20 according to the present invention can reproduce an input signal when an unexpected abnormality occurs in the apparatus, so that the cause analysis can be easily performed, and furthermore, This is extremely effective in resolving the drawbacks of the concentrator / multiplexer to provide a more reliable transmission system.

[0022]

As described above, the concentrator / multiplexer according to the present invention is provided with a cell buffer for sequentially holding a predetermined data amount of an input signal, and performs the holding operation of the cell buffer based on the occurrence of an abnormality. Stopping, when analyzing the cause of the occurrence of the abnormality, since the data stored in the cell buffer is read and the input signal is reproduced, the line multiplexing device that can easily analyze the processing operation at the time of the occurrence of the abnormality Can be realized.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating a configuration example of a line multiplexing apparatus according to the present invention.

FIG. 2 is a diagram illustrating a configuration example of a transmission system using an ATM.

FIG. 3 is a diagram showing an example of a transmission signal form on an ATM leased line.

FIG. 4 is a functional block diagram illustrating a configuration example of a concentrator / multiplexer according to the related art.

[Explanation of symbols]

 1a to 1n Terminal device 2 (2a, 2b) Concentrator / multiplexer 3a to 2n Terminal device 4 ATM dedicated line 5 UTOPIA interface line 6, 12 Transmission Route IF unit 7 ... Frame synchronization unit 8 ... Cell synchronization unit 9 ... ATM processing unit 10 ... UTOPIA interface unit 11 ... Frame generation unit 13 ... Common control unit 14 ... Cell Buffer 15 Memory 16 Memory control unit 17 Storage unit 20 Concentrator / multiplexer 30 Analysis device

Claims (1)

[Claims] A plurality of non-ATM interface lines and an AT
An ATM multiplexer for processing ATM cells based on a predetermined protocol in a line concentrator / multiplexer disposed between the ATM line and the M line.
A processing unit; a cell buffer for sequentially shifting and storing the ATM cells input to the ATM processing unit by a predetermined amount; and a storage unit connected to the cell buffer, wherein when an abnormality occurs in the ATM processing unit, By storing the contents of the cell buffer in the storage unit,
A line concentrator / multiplexer wherein the state of an input signal when the abnormality occurs can be reproduced.