JP2000244501A - Atm communication system and cell transmission rate controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cell waste due to the overflow of a buffer memory by allowing an opposing transmitting side to adjust the transmission rate of an effective ATM cell outputted at such a transmission rate as generates the overflow of the buffer memory on a receiving side by cell band control information. SOLUTION: When overflow is generated on the receiving side FIFO 2, a counting circuit 3 counts the number of wasted ATM cells based on a cell waste signal from the FIFO 2. A circuit 3a counts the free space of a buffer memory based on the number of cell space signal of the receiving side FIFO 2 and overlays information for adjusting the transmission rate of an effective cell. For example, when the number of free spaces of the buffer memory becomes only one cell, information for lowering the transmission rate of the effective ATM cells is overlaid to cell band control information, thereby the transmission rate of the effective cell can be lowered before the abandonment of cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an SDH (Sync).
Hronous Digital Hierarch
y) ATM using frame as transmission format
(Asynchronous Transfer Mo
de) The present invention relates to a communication system, and more particularly to control of a cell transmission rate when data is transferred via a buffer memory.

[0002]

2. Description of the Related Art Such an ATM communication system is provided with a buffer memory (FIFO) to buffer data, as disclosed in, for example, Japanese Patent Application Laid-Open No. 04-074046, to reduce fluctuations in data transmission speed. It has been proposed to absorb.

FIG. 5 shows a conventional receiving side circuit used in such an ATM communication system. The ATM cells transmitted from the SDH receiving device (not shown) are buffered by the receiving FIFO 2 through the cell synchronization circuit and the cell descrambler 1 (not shown). An ATM cell is transmitted as output data according to a request from the layer.

FIG. 6 shows a conventional transmitting side circuit. The ATM cell transmitted from the upper layer is buffered as input data in the transmission FIFO 6, and is transmitted via an empty cell insertion circuit 5 and cell scrambler 4 to an SDH (not shown)
The data is sequentially transmitted to the transmitting device. ATM on the sending FIFO6
If the cell is not buffered, the empty cell insertion circuit 5 sends the cell scrambler 4 and an SDH (not shown).
An empty cell is transmitted to the transmitting device.

[0005]

In the prior art described with reference to FIGS. 4 and 5, the transmission amount of cells requested from the upper layer to the receiving FIFO 2 is received from the SDH receiving apparatus due to fluctuations in transmission speed. When a period smaller than the transmission amount of the cells buffered in the side FIFO 2 continues,
An overflow occurs in the receiving FIFO2 and the ATM
Since a cell is discarded, a retransmission request must be made in an upper layer, which has a problem that data transmission is greatly affected.

It is a primary object of the present invention to provide a method of controlling a cell transmission rate in order to minimize the discard of ATM cells in a buffer memory due to fluctuations in the transmission rate.

Another object of the present invention is to provide an ATM communication system in which the above control method is implemented.

[0008]

An AT using an SDH frame as a transmission format according to the first aspect of the present invention.
M communication system, monitoring means for monitoring the state of the buffer memory on the receiving side, means for transmitting the cell band control information generated by the monitoring means to the opposite transmitting side, based on the cell band control information Effective A of opposing sender
Means for adjusting the transmission rate of the TM cell.

A method for controlling a cell transmission rate in an ATM communication system using an SDH frame as a transmission format according to a second aspect of the present invention includes the steps of monitoring a state of a buffer memory on a receiving side and generating cell band control information. And transmitting the cell band control information to an opposing transmitting side; and adjusting a transmission rate of an effective ATM cell of the opposing transmitting side based on the cell band control information. I have.

According to the cell band control information, a valid ATM cell output at a transmission rate at which a buffer memory overflows on the receiving side is adjusted on the opposite transmitting side.

Therefore, it is possible to reduce cell discard due to overflow of the buffer memory occurring on the receiving side, and it is possible to obtain an effect of enabling smooth data transmission.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to clarify the above and other objects, features and advantages of the present invention, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, there is shown a receiving circuit of an ATM communication system according to an embodiment of the present invention. The receiving side circuit includes a cell descrambler 1, a receiving side FIFO 2, and a counting circuit 3.

When an overflow occurs in the receiving FIFO 2, the counting circuit 3 counts the number of discarded ATM cells based on the cell discarding signal from the FIFO 2. Information for lowering the transmission rate of the ATM cell is carried.

The cell band control information includes an overhead area SOH existing in the SDH frame as shown in FIG.
(Section Overhead) or POH
(Path Overhead), and is transmitted from an SDH transmitting apparatus on the receiving side (not shown) to an SDH receiving apparatus on the opposite transmitting side.

Referring to FIG. 2, there is shown a transmitting side circuit of an ATM communication system according to an embodiment of the present invention. The transmission side circuit includes a transmission side FIFO 6, an empty cell insertion circuit 5, and a cell scrambler 4.

In the empty cell insertion circuit 5, an ATM cell is transmitted to the transmitting FIFO 6 based on cell band control information (information for lowering the transmission rate of valid ATM cells) obtained from an SDH receiver (not shown). Even in the case of buffering, empty cells are inserted at a rate of, for example, one out of every ten cells, and the effective ATM cell transmission rate is reduced.

An SDH frame carrying an ATM cell stream having a reduced effective transmission rate is received from an SDH transmitting device on the transmitting side via an SDH receiving device on the opposite receiving side, where buffer memory overflow has occurred. Side FI
Transmitted to FO2. Here, since the transmission speed of the valid ATM cells transmitted to the receiving FIFO 2 is reduced, the cell discard due to the overflow occurring in the receiving FIFO 2 is eliminated. As a result, the cell band control information generated by the counting circuit 3 carries information for restoring the effective ATM cell transmission rate, and is transmitted to the SDH receiver on the opposite transmitting side.

As described above, since the overflow of the buffer memory of the receiving side can be monitored and the transmission speed of the effective ATM cell transmitted from the SDH transmitting apparatus of the opposite transmitting side can be adjusted, the overflow of the buffer memory of the receiving side can be adjusted. As a result, it is possible to minimize the discarding of the ATM cells, and smooth data transmission becomes possible.

As another embodiment of the present invention, the basic configuration is as described above, but the counter circuit for generating the cell band control information of the receiving side circuit is further devised. The configuration is shown in FIG.

In FIG. 4, the counting circuit 3a includes a receiving side F
In addition to counting the number of discarded ATM cells based on the cell discard signal output from the FIFO 2, the receiving FI
Based on the cell empty number signal of the FO2, the empty space of the buffer memory is counted, and information for adjusting the effective cell transmission rate is added to the cell band control information. For example, when the number of vacancies in the buffer memory becomes one more cell, information for lowering the transmission rate of the valid ATM cell is added to the cell band control information, so that the valid ATM cell is discarded before the cell is discarded.
Cell transmission speed can be reduced.

As described above, according to the present embodiment, it is possible to prevent the discard of the ATM cells caused by the overflow of the buffer memory in advance, thereby enabling smooth data transmission.

It should be noted that the present invention is not limited to the above embodiments, and it is clear that the embodiments can be appropriately modified within the scope of the technical idea of the present invention.

[0024]

As described above, according to the present invention, an effective ATM cell output at a transmission rate at which the buffer memory overflows on the receiving side by the cell band control information is transmitted to the opposing transmitting side. By adjusting the transmission rate, it is possible to reduce cell discard due to buffer memory overflow occurring on the receiving side, and to provide an ATM communication system that realizes smooth data transmission.

[Brief description of the drawings]

FIG. 1 is a diagram showing a receiving side circuit of an ATM communication system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a transmission side circuit of the ATM communication system according to the embodiment of the present invention.

FIG. 3 is a diagram showing an example of an SDH frame when the present invention is applied.

FIG. 4 is a diagram showing a receiving side circuit of an ATM communication system according to another embodiment of the present invention.

FIG. 5 is a diagram showing a receiving-side circuit of a conventional ATM communication system.

FIG. 6 is a diagram showing a transmission side circuit of a conventional ATM communication system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 cell descrambler 2 receiving FIFO 3 counting circuit 3 a counting circuit 4 cell scrambler 5 empty cell insertion circuit 6 transmission FIFO

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[Procedure amendment]

[Submission date] May 19, 2000 (2005.1.
9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

In the prior art described with reference to FIGS . 5 and 6 , the transmission amount of cells requested from the upper layer to the receiving FIFO 2 is buffered from the SDH receiving apparatus to the receiving FIFO 2 due to fluctuations in the transmission speed. If the period less than the transmission amount of the cell continues, the receiving FIFO 2
In this case, an overflow occurs and the ATM cell is discarded. Therefore, a retransmission request must be made in an upper layer, which has a problem that data transmission is greatly affected.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

SUMMARY OF THE INVENTION According to the present invention, in an ATM communication system using an SDH frame as a transmission format, a receiver circuit monitors a state of a buffer memory of a receiver, and a monitor generated by the monitor means. Means for transmitting cell band control information to the opposing transmitting circuit, and means for adjusting the effective ATM cell transmission rate of the opposing transmitting circuit based on the cell band control information, When an overflow occurs in the receiving buffer memory, the number of cells discarded based on the cell discarding signal from the receiving buffer memory is counted in the counting circuit of the monitoring means, and the cell band control information from the counting circuit is counted. Information for lowering the transmission rate of an effective cell is placed, and the transmission rate is adjusted by the opposed transmitting side circuit. That. Further, according to the present invention, in an ATM communication system using an SDH frame as a transmission format, a receiving circuit opposes monitoring means for monitoring a state of a receiving buffer memory and cell band control information generated by the monitoring means. And a means for adjusting the effective ATM cell transmission rate of the opposing transmitting side circuit based on the cell band control information. The number of empty cells in the receiving buffer memory is counted based on the cell empty number signal from the receiving buffer memory, and information for adjusting the transmission rate of cells valid for the cell band control information from the counting circuit is provided. The transmission speed is adjusted by the opposing transmission-side circuit. Further, the present invention provides an ATM communication system using an SDH frame as a transmission format, wherein a receiving side circuit comprises:
Monitoring means for monitoring the state of the receiving buffer memory; means for transmitting cell band control information generated by the monitoring means to an opposing transmitting circuit; and the opposing transmitting side based on the cell band control information. Means for adjusting the effective ATM cell transmission rate of the circuit, wherein the counting circuit of the monitoring means counts the number of cells discarded based on the cell discard signal from the receiving buffer memory; and The number of empty cells in the receiving buffer memory is counted based on the cell empty signal from the receiving buffer memory, and information for adjusting the transmission rate of cells valid for the cell band control information from the counting circuit. And the transmission speed is adjusted by the opposing transmission side circuit. Also, the present invention provides an ATM communication system using an SDH frame as a transmission format, wherein the opposed transmission side circuit has a transmission side buffer memory and an empty cell insertion circuit, and transmits cell band control information from the reception side circuit. The transmission rate of an effective cell is adjusted based on whether or not an empty cell is inserted by the empty cell insertion circuit.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

The present invention also relates to a method for controlling a cell transmission rate in an ATM communication system using an SDH frame as a transmission format, wherein a step of monitoring a state of a buffer memory on a receiving side and generating cell band control information; Transmitting the band control information to the opposing transmitting circuit; and adjusting the effective ATM cell transmission rate of the opposing transmitting circuit based on the cell band control information; When an overflow occurs in the memory, the number of cells discarded based on the cell discard signal from the receiving buffer memory is counted, and information for lowering the effective cell transmission rate is added to the cell band control information, The transmission speed is adjusted by the opposing transmission side circuit. In addition, the present invention uses an SDH frame as a transmission format.
In a method for controlling a cell transmission rate of a TM communication system,
Monitoring the state of the buffer memory on the receiving side, generating cell band control information, transmitting the cell band control information to an opposing transmitting side circuit, and transmitting the opposing transmitting side based on the cell band control information. Effective AT of the circuit
Adjusting the transmission rate of M cells, wherein the number of empty cells in the receiving buffer memory is counted based on the cell empty number signal from the receiving buffer memory, and the number of cells available in the cell band control information is counted. The information for adjusting the transmission speed of the data is carried, and the transmission speed is adjusted by the opposed transmitting side circuit. Further, the present invention relates to S
In a method for controlling a cell transmission rate of an ATM communication system using a DH frame as a transmission format, a step of monitoring a state of a buffer memory on a receiving side and generating cell band control information; And adjusting the effective ATM cell transmission rate of the opposing transmitting side circuit based on the cell band control information, and discarding based on a cell discarding signal from the receiving side buffer memory. The number of vacant cells is counted, and the number of vacant cells of the receiving buffer memory is counted based on the cell vacancy signal from the receiving buffer memory. Information for adjustment is carried, and the transmission speed is adjusted by the opposed transmitting side circuit. The present invention also relates to a method for controlling a cell transmission rate of an ATM communication system using an SDH frame as a transmission format, wherein the opposed transmitting side circuit uses an empty cell inserting circuit based on the cell band control information from a receiving side. The transmission rate of an effective cell is adjusted depending on whether or not an empty cell is inserted.

Claims (19)

[Claims] In an ATM communication system using an SDH frame as a transmission format, monitoring means for monitoring a state of a buffer memory on a receiving side, and transmitting cell band control information generated by the monitoring means to an opposite transmitting side. Means for adjusting the transmission rate of valid ATM cells on the opposite transmitting side based on the cell band control information. 2. The apparatus according to claim 1, wherein the monitoring means for monitoring the state of the receiving buffer memory counts the number of cell discards in the receiving buffer memory to generate the cell band control information. An ATM communication system as described. 3. The apparatus according to claim 1, wherein the monitoring means for monitoring the state of the receiving buffer memory counts the number of empty cells in the receiving buffer memory to generate the cell band control information. An ATM communication system as described. 4. A monitoring means for monitoring the state of the receiving buffer memory counts the number of cell discards in the receiving buffer memory and the number of empty cells in the receiving buffer memory to generate the cell band control information. The ATM communication system according to claim 1, wherein the communication is performed. 5. When a cell is discarded when the buffer memory of the receiving side overflows, the monitoring means sets an AT
Generating cell band control information for lowering the transmission rate of M cells, and when the overflow is eliminated, the monitoring means generates cell band control information for restoring the transmission rate of the ATM cells. The ATM communication system according to claim 2, wherein 6. The monitoring means, when counting the number of empty cells in the receiving buffer memory, generates cell band control information for reducing the transmission rate of ATM cells, and generates the cell band control information due to overflow of the receiving buffer memory. The ATM communication system according to claim 3 or 4, wherein discarding of a cell is prevented in advance. 7. The communication device according to claim 1, wherein said means for transmitting said cell band control information to an opposing transmitting side carries said cell band control information on an overhead portion of an SDH frame. An ATM communication system according to any one of claims 1 to 3. 8. The method according to claim 1, wherein said means for adjusting the transmission rate of valid ATM cells on the opposite transmitting side is performed based on whether or not an empty cell is inserted between valid ATM cells. The ATM communication system according to any one of the above. 9. When the cell band control information is information for lowering the transmission rate of ATM cells, the means for adjusting the transmission rate of valid ATM cells on the opposite transmitting side is effective. 9. The ATM communication system according to claim 8, wherein empty cells are inserted between the ATM cells. 10. When the cell band control information is information for returning a transmission rate of an ATM cell, the means for adjusting the transmission rate of an effective ATM cell on the opposite transmitting side is effective. 9. The ATM communication system according to claim 8, wherein insertion of empty cells between ATM cells is stopped. 11. A method for controlling a cell transmission rate in an ATM communication system using an SDH frame as a transmission format, comprising: monitoring a state of a buffer memory on a receiving side and generating cell band control information; Transmitting to an opposing transmitting side; and adjusting a transmission rate of an effective ATM cell of the opposing transmitting side based on the cell band control information. Speed control method. 12. The ATM communication system according to claim 11, wherein the monitoring of the state of said receiving buffer memory is performed by counting the number of cell discards in said receiving buffer memory. Control method. 13. The ATM transmission system according to claim 11, wherein the monitoring of the state of the receiving buffer memory is performed by counting the number of empty cells in the receiving buffer memory. Control method. 14. The apparatus according to claim 11, wherein the monitoring of the state of the receiving buffer memory is performed by counting the number of cell discards in the receiving buffer memory and the number of empty cells in the receiving buffer memory. AT described
A method for controlling a cell transmission rate of an M communication system. 15. When a cell is discarded when the buffer memory of the receiving side overflows, cell band control information for lowering the transmission rate of the ATM cell is generated. 15. The method for controlling a cell transmission rate in an ATM communication system according to claim 12, wherein cell band control information for restoring the transmission rate of the cell is generated. 16. Counting the number of empty cells in the receiving buffer memory generates cell band control information for lowering the transmission rate of ATM cells, and discards cells generated due to overflow of the receiving buffer memory. The method according to claim 13 or 14, wherein the control is performed in advance. 17. The method according to claim 11, wherein the transmission rate of the valid ATM cells on the opposite transmitting side is adjusted based on whether or not an empty cell is inserted between the valid ATM cells.
17. The method for controlling a cell transmission rate of an ATM communication system according to any one of 16. 18. When the cell band control information is information for lowering the transmission rate of an ATM cell, adjustment of the transmission rate of an effective ATM cell on the opposite transmitting side is performed by:
18. The method according to claim 17, wherein the method is performed by inserting an empty cell between valid ATM cells. 19. When the cell band control information is information for returning a transmission rate of an ATM cell, the adjustment of the transmission rate of the valid ATM cell on the opposite transmitting side is performed by adjusting the valid ATM cell. 18. The method according to claim 17, wherein the control is performed by stopping the insertion of empty cells between the cells.