JPH07170269A - Data transfer device - Google Patents

Abstract

PURPOSE:To suppress the time required for retransmission accompanying abandonment cell generation to minimum by measuring the interval of the abandonment cell generation occuring in an ATM transmission line in real time and adjusting the length of transfer data corresponding to the abandonment interval. CONSTITUTION:This data transfer device is provided with a transmission part 100 and a reception part 200 through an asynchronous transmission mode (ATM) communication network, the transmission part 100 is provided with a means for gathering cells to be transmitted by every plural N pieces, adding error detection codes and transmitting them and the reception part 200 is provided with the means for conducting error detection for the plural N pieces of the cells and performing reception. Also, the transmission part 100 is provided with the means for adding a sequence number to every plural N pieces of the cells, the reception part 200 is provided with the means for detecting abandonment cells from the sequence number and generating the generation information of the abandonment cells and a control means for feeding back the generation information of the abandonment cells from the reception part 200 to the transmission part 100 and changing the value of N is provided. Then, the generation interval is measured in the reception part 200 and fed back to the transmission part 100 and a transmission cell length is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used for data transfer using an ATM (Asynchronous Transfer Mode) communication network. The present invention relates to a data transfer device capable of reducing loss of data due to the influence of discarded cells and improving transmission efficiency.

[0002]

2. Description of the Related Art Conventionally, when data is transferred, an error detection signal is inserted for each predetermined data length, and when an error occurs, retransmission is performed for each predetermined data length. .

As conventional techniques, a technique for variably setting the ATM packet transmission rate (see Japanese Patent Laid-Open No. 2-98256) and a technique for changing the transmission cell interval according to the traffic of the ATM communication network (Japanese Patent Laid-Open No. 3-136432). (See Japanese Patent Publication).

[0004]

When data is transferred using an ATM transmission line, there is a problem that when the cell discard, which is a feature of the ATM transmission line, occurs, information of the discarded cells is lost. .

Since the frequency of cell discard depends on the load condition of the transmission path, the interval between cell discards is likely to be short when the load on the transmission path is large. If the data length is long, data errors frequently occur. As a result, retransmission is repeated and the data transfer efficiency decreases. Conversely, if the load on the transmission path is light, the interval between cell discards is likely to be long, and even if the data length is long, it is possible to transfer data without error, but the error detection signal becomes useless and the data transfer efficiency is low. There is a problem.

[0006] The present invention has been made under such a background, and with respect to the cell discard generated in the ATM transmission line,
An object of the present invention is to provide a device capable of efficiently using a transmission line by reducing loss of data due to the influence of a discarded cell.

[0007]

SUMMARY OF THE INVENTION The present invention comprises a transmitter and a receiver connected through an ATM communication network, and the transmitter collects a plurality of N cells to be transmitted and outputs an error detection code. In the data transfer apparatus, the data transfer apparatus further comprises means for transmitting and attaching the plurality of N cells, and the receiving section includes means for performing error detection on the plurality of N cells and receiving the sequence. A means for numbering is provided, the receiving section is provided with means for detecting a discarded cell from the sequence number and generating generation information of the discarded cell, and the generation information of the discarded cell is fed back from the receiving section to the transmitting section. The N
It is characterized in that a control means for changing the value of is provided.

The transmitting means comprises a buffer (101) for temporarily storing input transmission data, a cell assembling circuit (102) for assembling a plurality of M pieces of data extracted from the buffer into one cell, and the cell assembling. And an error detection code insertion circuit (104) for adding N bits of output cells of the circuit and adding an error detection code. The control means is provided in the reception unit, and an ATM cell measurement result of the discarded cell interval is provided.
Cellizing circuit for converting cells into cells that can be transmitted through a communication network (20
7) and a cell disassembly circuit (109) provided in the transmission section for disassembling the cell containing the measurement result, and a cell length determination circuit (107) for determining N from the disassembly information
A cell counter (108) for setting the number of read cells of the buffer (101) according to the cell length, and N received N-cells as means for detecting discarded cells from the sequence number and generating generation information of the discarded cells. Sequence number separation circuit (201) for separating the sequence number added to each cell, a discard cell detection circuit (202) for detecting a discard cell from the sequence number, and a discard cell interval for measuring the generation interval of the discard cell It is desirable to include a measurement circuit (205).

[0009]

When transmitting the data sequence in the asynchronous transmission mode (ATM), the transmitting side assembles cells for each M data (M is a natural number) of the data sequence, and the cells are assembled with the cell length N (N). Is a natural number), and an error detection signal is added to each cell having a cell length of N and transmitted. The receiving side disassembles the received cells having a cell length of N, and when an error is detected, transmits a retransmission request signal requesting the retransmission of the cells having a cell length of N cells. The transmitting side retransmits cells having a cell length of N according to the retransmission request signal.

In such an operation, the transmitting side sequentially adds consecutive sequence numbers to the cells, and the receiving side separates the sequence numbers added to the received cells to determine the continuity of the sequence numbers. Then, the discarded cells are detected, the generation time intervals of the detected discarded cells are measured, and the discarded cell generation time intervals are transmitted to the transmission side. On the transmission side, the cell length N is determined according to the discarded cell generation interval.

[0011] With this, it is possible to measure the interval of the discarded cells actually occurring in the ATM transmission line in real time, adjust the length of the transfer data according to the measured discarded cell occurrence interval, and discard the discarded cells. The time required for retransmission due to occurrence can be minimized.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment of the present invention.

The embodiment of the present invention comprises a transmission section 100 and a reception section 200 connected via an ATM communication network, and the transmission section 100 collects a plurality of N cells to be transmitted and adds an error detection code. The receiving unit 200 includes a unit that performs error detection on the plurality N of cells and receives the error detection unit.
00, means for assigning a sequence number to each of a plurality of N cells is provided, and the receiving unit 200 is provided with means for detecting a discarded cell from the sequence number and generating generation information of the discarded cell, and generating the generation information of the discarded cell. From the receiving unit 200 to the transmitting unit 10
A control means for changing the value of N by returning to 0 is provided.

The transmitting means includes a buffer 101 for temporarily storing input transmission data, and the buffer 101.
A first cell assembling circuit 102 for assembling a plurality of M pieces of data taken out from one cell into one cell, and an error detecting code insertion for putting together N pieces of output cells of the first cell assembling circuit 102 and adding an error detecting code. The control means includes a circuit 104 and a second cell conversion circuit 207 which is provided in the reception unit 200 and converts the measurement result of the discarded cell interval into cells that can be transmitted by the ATM communication network, and further includes the transmission unit 100. Cell disassembling circuit 1 provided in a cell and disassembling a cell including measurement results
09, a cell length determination circuit 107 that determines the N from the decomposition information, and a buffer 101 according to the cell length.
Cell counter 108 for setting the number of read cells of.

The received N is used as a means for detecting a discarded cell from the sequence number and generating information on the generation of the discarded cell.
A sequence number separation circuit 201 for separating the sequence number added to each cell, a discarded cell detection circuit 202 for detecting a discarded cell from the sequence number, and a discarded cell interval measurement circuit 205 for measuring the generation interval of the discarded cells.
Including and

Further, in the transmitting section 100, an error detection code generating circuit 103 for generating an error detecting signal, and a means for transmitting with the addition of the sequence number is a sequence number generating circuit 105 for generating a sequence number, And a sequence number adding circuit 106 for transmitting the added sequence number, and the receiving unit 200 includes an error detecting circuit 203 for receiving the cell from the transmitting unit 100 and detecting an error.
And a cell disassembly circuit 204 that disassembles cells in which no error is detected and transmits as received data, and an error detection circuit 20.
3 includes a retransmission request signal generation circuit 206 that generates a retransmission request signal requesting the transmission unit 100 to transmit cells of the cell length N when the error is detected.

Now, the data transfer path of the embodiment of the present invention having such a configuration will be described.

The transmission data 1 input from the input terminal A is input to the buffer 101, and the transmission data 2 is output from the buffer 101 and input to the first cell formation circuit 102. The transmission cell 3 is output from the first cell assembling circuit 102. The transmission cell 3 is input to the error detection code generation circuit 103 and the error detection code insertion circuit 104. The error detection code generation circuit 103 outputs the error detection code 4. The error detection code 4 is input to the error detection code insertion circuit 104, and the transmission cell 5 and the cell synchronization signal 6 are output from the error detection code insertion circuit 104. The transmission cell 5 is input to the sequence number addition circuit 106, and the cell synchronization signal 6 is input to the sequence number generation circuit 105. The transmission sequence number 7 is output from the sequence number generation circuit 105, and this transmission sequence number 7 is input to the sequence number addition circuit 106. Sequence number addition circuit 106
Then, the transmission cell 8 is output to the transmission line via the transmission line output terminal B.

When the transmission cell 8 output from the transmission unit 100 from the transmission line is input to the transmission line input terminal C as the reception cell 9, the reception cell 9 is input to the sequence number separation circuit 201, and the sequence number separation circuit 201 outputs it. Is the receiving cell 1
0 and reception sequence number 11 are output. Receiving cell 1
0 is input to the error detection circuit 203, and the received sequence number 11 is input to the discarded cell detection circuit 202. The error detection circuit 203 outputs the reception cell 12 and the error determination signal 13, the reception cell 12 is input to the cell disassembly circuit 204, and the error determination signal 13 is input to the retransmission request signal generation circuit 206. Received data 14 from the cell disassembly circuit 204
Is output via the output terminal D. The discarded cell detection circuit 202 outputs the discarded cell determination signal 15 to the discarded cell interval measurement circuit 205, and the discarded cell interval measurement circuit 205 outputs the discarded cell generation interval 16. The discarded cell generation interval 16 is input to the second cell conversion circuit 207. The retransmission request signal 17 is output from the retransmission request signal generation circuit 206, and the retransmission request signal 17 is input to the second cell conversion circuit 207. The transmission resend request cell 18 is output from the second cell conversion circuit 207 to the transmission line via the transmission line output terminal E.

The reception resend request cell 19 is input from the transmission path to the transmission path input terminal F of the transmission unit, and the reception resend request cell 19 is input.
Is input to the cell disassembly circuit 109. Cell disassembly circuit 10
From 9, a discarded cell generation interval 20 and a retransmission request signal 21 are output. The discarded cell generation interval 20 is the cell length determination circuit 10
7, the retransmission request signal 21 is input to each cell counter. The transmission cell length 22 is input from the cell length determination circuit 107 to the cell counter 108. Cell counter 108
Outputs an error detection code calculation enable signal 23, an error detection code insertion timing signal 24, and a buffer read signal 25. Error detection code operation enable signal 2
3 is to the error detection code generation circuit 103, the error detection code insertion timing signal 24 is to the error detection code insertion circuit 104,
The buffer read signal 25 is input to the buffer 101, respectively.

Next, the operation of the embodiment of the present invention will be described. The transmission data 1 from the input terminal A is written in the buffer 101, and the transmission data 1 written in the buffer 101 is read from the buffer 101 according to the buffer read signal 25. As the buffer read signal 25, only the data of the number “N” of cells having the transmission cell length 22 determined by the cell length determination circuit 107 is read from the buffer 101. The first cell assembling circuit 102 divides the input transmission data 2 every M pieces and adds a cell header to assemble a cell. The error detection code generation circuit 103 calculates the parity of the input data for N cells and outputs it as the error detection signal 4. The error detection code insertion circuit 104 multiplexes the error detection code 4 into the transmission cell 3. The sequence number generation circuit 105 counts the cell synchronization signal 6 and generates a continuous number to be added to the transmission cell 5, that is, a transmission sequence number 7. The sequence number addition circuit 106 multiplexes the transmission sequence number 7 into the transmission cell 5.

Sequence number separation circuit 2 of receiving section 200
In 01, the multiplexed sequence number of the receiving cell 9 is separated. The error detection circuit 203 calculates the parity of the data for N cells and detects the error, and outputs the error determination signal 13 when the error is detected. The discard cell detection circuit 202 determines the continuity of the separated reception sequence numbers, and when discontinuity occurs, determines that a discard cell has occurred and outputs a discard cell determination signal 15. The discard cell interval measuring circuit 205 measures the generation interval time of the discard cell determination signal 15 and outputs the generation interval time as the discard cell generation interval 16. The retransmission request signal generation circuit 206 outputs the error determination signal 13
When the error occurs, the retransmission request signal 17 is output. In the second cell conversion circuit 207, a cell header is added to the discard cell generation interval 16 and the retransmission request signal 17, and the transmission retransmission request cell 18 is assembled and output.

The cell disassembly circuit 109 separates the reception retransmission request cell 19 from the discarded cell generation interval 20 and the retransmission request signal 21. In the cell length determination circuit 107, the discarded cell occurrence interval 2
The transmission cell length 22 is determined according to 0. As a determination method, when the discarded cell occurrence interval 20 is T cells, the transmission cell length 22 “N” is N cells = (1 + a) × T cells: a is a positive real number and has a margin.

By the above operation, the discarding cell generation interval generated in the transmission line is measured in the receiving section 200, the discarding cell generation interval is fielded back to the transmitting section 100, and the cell length to be transmitted is determined from the discarding cell generation interval.

[0025]

As described above, according to the present invention, A
The time required for retransmission due to the occurrence of a discarded cell is minimized by measuring the actual interval of the discarded cell occurrence on the TM transmission line in real time and adjusting the length of the transfer data according to the measured discarded cell occurrence interval. There is an effect that can be suppressed to the limit.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

[Explanation of symbols]

 1, 2 Transmission data 3, 5, 8 Transmission cell 4 Error detection code 6 Cell synchronization signal 7 Transmission sequence number 9, 10, 12 Reception cell 11 Reception sequence number 13 Error determination signal 14 Reception data 15 Discarded cell determination signal 16, 20 Discarded cell generation interval 17, 21 Retransmission request signal 18 Transmission retransmission request cell 19 Reception retransmission request cell 22 Transmission cell length 23 Error detection code operation enable signal 24 Error detection code insertion timing signal 25 Buffer read signal 100 Transmitter 101 Buffer 102 First Cell conversion circuit 103 error detection code generation circuit 104 error detection code insertion circuit 105 sequence number generation circuit 106 sequence number addition circuit 107 cell length determination circuit 108 cell counters 109 and 204 cell disassembly circuit 200 reception unit 201 sequence number separation circuit 02 discarded cell detection circuit 203 the error detection circuit 205 discards the cell interval measuring circuit 206 the retransmission request signal generation circuit 207 the second cell of the circuit A input terminal B, E transmission path output terminal C, F transmission path input terminal D output terminal

Claims (3)

[Claims] 1. A transmission unit and a reception unit connected via an ATM communication network, and the transmission unit has a unit for collectively transmitting a plurality of N cells to be transmitted with an error detection code. In the data transfer device, the receiving unit has means for performing error detection on the plurality of N cells and receiving the error, wherein the transmitting unit is provided with a unit for giving a sequence number to each of the N cells. The receiving unit is provided with means for detecting a discarded cell from the sequence number and generating information on the generation of the discarded cell, and controlling the return of the generation information of the discarded cell from the receiving unit to the transmitting unit to change the value of N. A data transfer device comprising means. 2. The transmitting means comprises a buffer for temporarily storing input transmission data, a cell assembling circuit for assembling a plurality of M pieces of data extracted from the buffer into one cell, and an output cell of the cell assembling circuit. And an error detection code insertion circuit for adding N error detection codes to each other and adding the error detection code, wherein the control unit is provided in the reception unit, and converts the measurement result of the discarded cell interval into cells that can be transmitted through the ATM communication network. A cell disassembling circuit for disassembling a cell including a measurement result, the cell disassembling circuit for determining the N from the disassembly information, and the buffer of the buffer according to the cell length. The data transfer device according to claim 1, further comprising a cell counter for setting the number of read cells. 3. The received N as means for detecting a discarded cell from the sequence number and generating information on the generation of the discarded cell.
It includes a sequence number separation circuit for separating the sequence number added to each cell, a discarded cell detection circuit for detecting a discarded cell from the sequence number, and a discarded cell interval measurement circuit for measuring the generation interval of the discarded cells. The data transfer device according to claim 1.