JPH08316966A - Atm cell transmitter - Google Patents

Abstract

PURPOSE: To reduce the number of times of the retransmission of a cell by having a monitoring circuit monitoring data quantity to be fetched in a cell generation means for every reference time and a circuit controlling cell transmission speed in accordance with the monitoring output of the monitoring circuit. CONSTITUTION: A data packet processing circuit 1 stores a received data packet and a data packet to be retransmitted and transmits the packets to a data packet decomposition circuit 2 after properly arranging the order of the packets. At this time, transmitted packet amount is notified to a throughput monitoring circuit 5 by a signal a. The circuit 5 receives a signal b from a reference time generation circuit 6 for every unit time, calculates the transmission throughput of the data packet from the packet amount transmitted within unit time and notifies the throughput to a cell transmission speed control circuit 7. The circuit 7 determines cell transmission speed from the fluctuation of the throughput for every unit time and notifies the result to a cell transmission circuit 4. The circuit 4 transmits the cell by the timing according to the cell transmission speed notified by the circuit 7 based on a reference clock e.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an ATM (Asynchronous Trunk).
ansfer Mode) Used for the network. In particular, it relates to a technique for improving the throughput of an ATM cell transmission device.

[0002]

2. Description of the Related Art A conventional example in which cells, which are fixed-length data packets, are communicated between ATM data terminals is shown in FIG.
Will be described with reference to. FIG. 4 is a diagram showing a processing flow of the ATM cell transmitting apparatus of the conventional example. In the ATM cell transmission device, each application delivers a data packet to a data transfer protocol (TCP / IP, etc.), and the data transfer protocol performs unique processing and then AAL (ATM Adapt
the protocol data unit to the application layer). A
In AL, this unit is processed according to each AAL type and then disassembled into ATM cells (AAL-PDU: AAL-P
rotocol Data Unit).

The disassembled cells are transmitted by the ATM cell transmission device at a predetermined maximum speed or less in a connection established between a transmission terminal and a reception terminal in the ATM network. The receiving terminal assembles the original data packet after receiving the cell. As a result, cell communication is performed between the transmitting and receiving terminals.

At this time, in the ATM cell transmitting apparatus of the transmitting terminal, cells are transmitted at intervals (minimum intervals) indicated by the reciprocal of the maximum speed as long as there are cells in the transmitting buffer. Transmission is stopped.

[0005]

When a cell is transferred on the connection established between the transmitting terminal and the receiving terminal, the ATM cell transmitting device of the transmitting terminal respects the maximum speed determined in advance. Nevertheless, cell loss may occur due to congestion at an exchange or other relay node relaying the connection. At this time, an error may occur in the data packet assembled by the receiving terminal, or the data packet may be omitted. In the cell communication between the transmitting and receiving terminals, if the transmitter has a resend function, an error has occurred from the transmitting terminal,
Alternatively, it is guaranteed that the correct data packet is received by retransmitting the dropped cell. But,
When the cell loss occurrence frequency is high, the communication throughput of the cell is reduced due to frequent retransmission between the transmitting and receiving terminals.

The present invention has been made against such a background, and an object thereof is to provide an ATM cell transmitting apparatus capable of increasing or decreasing the cell transmitting speed according to the amount of data to be transmitted. It is an object of the present invention to provide an ATM cell transmitting device that can reduce the number of cell retransmissions. An object of the present invention is to provide an ATM cell sending device capable of improving the communication throughput of cells.

[0007]

According to the present invention, the cell transmission rate is increased or decreased according to the amount of data to be transmitted.
The main feature is that it does not cause excessive congestion in the ATM network.

That is, according to the present invention, the AT is converted from the input data.
A cell provided with a cell generation means for generating M cells, a cell storage circuit for temporarily storing the ATM cells, and a cell transmission circuit for transmitting the read output of the cell storage circuit to the ATM communication network.
This is a TM cell transmission device. Here, a feature of the present invention is that a monitoring circuit for monitoring the amount of data taken into the cell generating means at each reference time, and a cell transmission speed control for controlling the cell transmission speed according to the monitoring output of this monitoring circuit. It is equipped with a circuit.

The data taken in by the cell generation means is in the packet format, and the cell generation means performs the data protocol processing on the data in the packet format, and the protocol data unit output from the processing circuit. And a data packet disassembling circuit for disassembling ATM cells to generate ATM cells, and the amount of data monitored by the monitoring circuit is preferably the number of data packets processed by the data packet processing circuit within a reference time.

[0010]

In the ATM cell transmitting apparatus, the throughput of data transmission, that is, the amount of data packets delivered by the application to the data transfer protocol per unit time is monitored during communication. According to the result of this monitoring, the cell transmission speed is increased or decreased according to the data packet amount. One AT
By performing such control in many of the ATM cell transmission devices existing in the M network, it is possible to suppress an increase in the cell loss occurrence frequency as an ATM network unit, thereby suppressing the occurrence frequency of the lost cell retransmission, and reducing the data packet. To prevent a decrease in communication throughput.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an apparatus according to the present invention.

According to the present invention, there is provided a cell generation unit 10 as a cell generation means for generating an ATM cell from input data,
This is an ATM cell transmission device including a cell storage circuit 3 for temporarily storing TM cells and a cell transmission circuit 4 for transmitting the read output of the cell storage circuit 3 to an ATM communication network.

Here, the feature of the present invention is that the throughput monitoring circuit 5 monitors the amount of data taken into the cell generator 10 at each reference time, and the cell transmission rate according to the monitoring output of the throughput monitoring circuit 5. And a cell transmission speed control circuit 7 for controlling

The data taken in by the cell generation unit 10 is in the packet format, and the cell generation unit 10 outputs the data packet processing circuit 1 for performing the data protocol processing on the data in the packet format and the data packet processing circuit 1. AT by disassembling protocol data unit
A data packet decomposition circuit 2 for generating M cells,
The data amount monitored by the throughput monitoring circuit 5 is the number of data packets processed by the data packet processing circuit 1 within the reference time generated by the reference time generation circuit 6.

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a diagram showing the relationship between cell retransmission frequency and throughput. The horizontal axis represents the frequency of retransmission occurrence, and the vertical axis represents the throughput. FIG. 3 is a diagram showing a flow of processing of the ATM cell transmitting apparatus according to the embodiment of the present invention. When data packets are communicated between a sending terminal and a receiving terminal on a connection that does not cause cell loss, the number of retransmissions due to data packet errors and omissions is small. The packet communication speed also increases, and as a result, the data communication throughput also increases. However, as shown in FIG. 2, when the cell loss occurrence frequency becomes high due to the congestion of the relay node, frequent retransmissions cause a decrease in throughput (point in FIG. 2 □). In this case, the lower the cell inflow rate to the buffer in the node relaying the connection, the lower the cell loss frequency. Therefore, the cell transmission rate in the ATM cell transmission device of the transmission terminal is reduced. As a result, the frequency of occurrence of cell loss in the buffer and the frequency of data packet retransmission due to cell loss are also reduced. When the maximum cell transmission rate is controlled within the range in which the influence of the decrease in cell transmission rate is dominant (point in Figure 2), but in the range in which the impact of decrease in retransmission frequency is dominant (point in Figure 2 ○) In addition, the present invention is effective in improving the reduction in throughput. In the embodiment of the present invention, as shown in FIG.
The transmission throughput when the application is handed over to the data transfer protocol is monitored, and the cell transmission speed is controlled according to the monitoring result.

Returning to FIG. 1 again, the flow of processing will be described more specifically. First, the data packet processing circuit 1 accumulates the data packets received from the application and the data packets to be retransmitted, and arranges them in order to pass them to the data packet disassembling circuit 2. At this time, the passed packet amount is notified to the throughput monitoring circuit 5 by the transmission packet amount signal a. The throughput monitoring circuit 5 receives the unit time elapsed signal b from the reference time generation circuit 6 for each unit time, and calculates the data packet transmission throughput from the amount of packets transmitted within the unit time. The calculated throughput is notified to the cell transmission rate control circuit 7 by the throughput monitor signal c. The cell sending speed control circuit 7 determines the cell sending speed from the fluctuation of the throughput per unit time, and notifies the cell sending circuit 4 of the result by the cell sending speed signal d. The packet received by the data packet decomposing circuit 2 is decomposed into ATM cells and then accumulated in the cell accumulating circuit 3. This cell is sent out on the transmission line by the cell sending circuit 4. At this time, the cell sending circuit 4 is provided with the reference clock signal e from the reference time generating circuit 6, and the cell sending circuit 4 sends the cell based on this reference clock signal e. The cells are transmitted at a timing (cell transmission interval) according to the cell transmission rate notified by the rate control circuit 7.

[0017]

As described above, according to the present invention,
Since the cell transmission rate can be increased or decreased according to the amount of data to be transmitted, the number of times of cell retransmission can be reduced. As a result, the communication throughput of cells in the ATM network can be improved.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between cell retransmission frequency and throughput.

FIG. 3 is a diagram showing a processing flow of an ATM cell transmission device according to the embodiment of the present invention.

FIG. 4 is a diagram showing a processing flow of a conventional ATM cell transmission device.

[Explanation of symbols]

 1 Data Packet Processing Circuit 2 Data Packet Decomposition Circuit 3 Cell Storage Circuit 4 Cell Transmission Circuit 5 Throughput Monitoring Circuit 6 Reference Time Generation Circuit 7 Cell Transmission Speed Control Circuit 10 Cell Generation Unit a Transmitted Packet Volume Signal b Unit Time Elapsed Signal c Throughput Monitoring Signal d Cell transmission speed signal e Reference clock signal

Claims (2)

[Claims] 1. A cell generation circuit for generating an ATM cell from input data, a cell storage circuit for temporarily storing the ATM cell, and a cell transmission circuit for transmitting a read output of the cell storage circuit to an ATM communication network. The ATM cell transmission device further comprises a monitoring circuit for monitoring the amount of data taken into the cell generating means at each reference time, and a cell transmission speed control circuit for controlling the cell transmission speed according to the monitoring output of this monitoring circuit. An ATM cell transmission device characterized by the above. 2. The data taken in by the cell generation means is in a packet format, and the cell generation means carries out a data protocol processing on the data in the packet format, and a protocol output from the processing circuit. 2. A data packet decomposing circuit for decomposing a data unit to generate an ATM cell, wherein the amount of data monitored by the monitoring circuit is the number of data packets processed by the data packet processing circuit within a reference time. ATM cell sending device.