KR100458828B1 - Buffer Control Apparatus and Method of ATM Switching System - Google Patents

Abstract

The present invention relates to an apparatus and method for controlling a buffer in an ATM switch that distinguishes real-time traffic from non-real-time traffic so as to first process real-time traffic.

In the conventional ATM switching system, data is temporarily stored using a common buffer method. Therefore, data transmission is performed in the order of input, regardless of service class, so that data requiring real-time processing is not processed in real time. There is a problem that can not satisfy the quality.

The present invention distinguishes the classes of input data and stores them in a buffer divided by classes, and outputs the data stored in the buffers according to the priority of the classes so that real-time traffic can be processed first, thereby improving the quality of service. You can be satisfied.

Description

Buffer Control Apparatus and Method of ATM Switching System

The present invention relates to a buffer control apparatus and method of an ATM switch, and more particularly, to a buffer control apparatus and method of an ATM switch which distinguishes real-time traffic from non-real-time traffic so as to prioritize real-time traffic.

In general, ATM allows various kinds of services to be accommodated in one communication network called B-ISDN, and ATM services include Constant Bit Rate (CBR), Variable Bit Rate (VBR), Available Bit Rate (ABR), and Unavailable (UBR). Bit Rate).

The CBR service described above is a service mainly applied to real-time services such as circuit emulation or interactive or broadcast video and audio services, and always provides a fixed transmission bandwidth, and guarantees quality of service for cell delay and loss rate. .

In VBR service, the service bit rate is specified by a statistical parameter that allows a change within a certain range, and the link can be efficiently used by statistical multiplexing.

The ABR service transmits high speed data while maximizing the available bandwidth of the link that is not used by CBR and VBR traffic while ensuring the minimum cell rate.

UBR service is a service that transmits data by using the remaining bandwidth used by CBR, VBR and ABR traffic. It is used for e-mail or file transfer service because there is no guarantee of quality of service for cell delay or cell loss.

As described above, in the ATM switch which provides various types of services, as shown in FIG. 1, when data is input through an input module using a common buffer scheme, the data is input to the common buffer 10. The data is stored for a while and then transmitted through the output module in the order of input. When using the common buffer method, a cell delay variation (CDV) occurring between data can be eliminated. .

As described above, in the conventional ATM exchanger, the cell delay variation can be eliminated by temporarily storing data using a common buffer method, but the data is output in the order of input without distinguishing the service class. .

Therefore, when CBR data requiring real time processing is input later than UBR data which may be processed in real time, CBR data is transmitted after UBR data is transmitted, thereby satisfying the Quality of Service (QoS). There is a problem that can not be.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and the service quality is satisfied by storing the input data in a buffer divided by class, extracting and outputting the data stored in the buffer according to the priority of the class. It is an object of the present invention to provide an apparatus and a method for controlling a buffer of an ATM exchange.

1 is a view for explaining a buffer control method of a conventional ATM switch.

Figure 2 is a diagram showing the configuration of a buffer control device of the ATM switch according to the present invention.

3 is a diagram showing the configuration of a class discriminating table provided in the class discriminating unit by way of example.

Figure 4 illustrates the configuration of a class buffer management table applied to the present invention by way of example.

FIG. 5 is a diagram for explaining a process of storing data in a corresponding class buffer according to the present invention. FIG.

6 is a flowchart for explaining a buffer control method of an ATM exchange according to the present invention;

*** Explanation of symbols for the main parts of the drawing ***

110. class buffer section, 120. buffer section,

121. real-time buffer, 123. non-real-time buffer,

125.VBR buffer, 127.ABR buffer,

129. UBR buffer, 130. Buffer control unit,

140. Priority Control

In order to achieve the above object, a buffer control apparatus of an ATM switch according to the present invention, when data is input through a predetermined data channel, class discriminates the class of the received data according to the class specified when the data channel is set up. Wealth; A buffer unit which is divided into a class buffer corresponding to the number of classes and stores data received from the class discriminating unit; A buffer control unit for storing the data distinguished by the class in the class discriminating unit in a corresponding class buffer, increasing the number of data stored in the corresponding class buffer by one, and linking the previously stored data using a linked list structure; And a priority control unit for extracting and outputting data stored in the buffer unit according to the priority of the class, and reducing the number of data stored in the corresponding class buffer by one.

On the other hand, the buffer control method of the ATM switch according to the present invention, if the data is input through a predetermined data channel, the process of determining the class buffer to store the received data by searching the class identification table by the ID of the data channel and ; A storing step of storing the received data in the class buffer; It includes the output process of extracting and outputting data from the selected class buffer according to the priority.

The storing may include: determining whether the received data may be stored in the class buffer using the buffer size of the class buffer and the number of data currently stored in the class buffer; If it is determined that the received data can be stored in the class buffer, storing the received data in a corresponding area of the class buffer; Reading address information of the last data stored in the class buffer from a class buffer management table; Generating a linked list by recording an address of the stored data in a link list portion of previously stored data based on the read address information; Changing address information of the last data stored in the class buffer to address information of the stored data; And increasing the number of data stored in the class buffer by one.

The output may include: determining whether data exists in a selected class buffer according to a priority; Reading the address information of the first data stored in the class buffer from the class buffer management table when there is data in the class buffer as a result of the determination; Reading and outputting data from a corresponding area of the class buffer based on the read address information; Changing address information of the first data stored in the class buffer to address information recorded in the link list portion of the output data; It characterized in that the process of reducing the number of cells stored in the class buffer by one.

In this case, if the data does not exist in the class buffer as a result of the determination, the data stored in the class buffer of the next priority is output or next priority depending on whether data exists in the class buffer of the next priority. And outputting the data stored in the class buffer of the rank.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the buffer control apparatus and method of the ATM switch according to an embodiment of the present invention.

2 is a road showing a configuration of a buffer control apparatus of an ATM switch according to the present invention, including a class discriminating unit 110, a buffer unit 120, a buffer control unit 130, and a priority control unit 140. Is done.

In such a configuration, when data (= cell) is input through a specific data channel, the class discriminator 110 searches for a class discrimination table with an ID of a specific data channel receiving the data, and assigns a class assigned to the corresponding channel. Find out.

3 is a diagram illustrating an example of a configuration of a class discrimination table provided in a class discriminating unit. In the class discriminating table, a data channel ID currently set and a class designated at the time of setting the data channel are stored in one-to-one correspondence. have.

Therefore, if the class of the first data channel is set to CBR when the first data channel is set, all classes of data input through the first data channel are distinguished by CBR.

On the other hand, the buffer unit 120 is divided into a class buffer corresponding to the number of classes, the real-time buffer 121 is stored largely real-time data such as CBR data, and non-real-time data such as VBR, ABR, UBR data, etc. The non-real time buffer 123 is stored, and the non-real time buffer may be divided into the VBR buffer 125, the ABR buffer 127, and the UBR buffer 129. Here, the buffer unit 120 is implemented as a common buffer, the number of buffers divided and the buffer size is adjusted by the operator.

The operator can adjust the number of buffers and the buffer size divided by designating the class type and the buffer size specified for each class provided in the class buffer management table.

As such, the buffer unit 120 stores the data received from the class discriminator 110 under the control of the buffer controller 130 in the corresponding class buffer.

4 is a diagram illustrating a configuration of a class buffer management table according to the present invention. In the class buffer management table, a class type, a buffer size specified for each class, a number of cells stored in the class buffer, and a corresponding class buffer are shown. The address information of the first cell stored in the cell and the address information of the last cell stored in the corresponding class buffer are stored.

Meanwhile, if there is data input through a specific channel, the buffer controller 130 stores the data distinguished by the class discriminator 110 in the corresponding class buffer, and increases the number of data stored in the corresponding class buffer by one. When the data is stored, the data is linked with previously stored data using a linked list structure.

FIG. 5 is a diagram illustrating an example of a process of storing data in a corresponding class buffer according to the present invention. When a third cell is input in a state in which a second cell is stored in the corresponding class buffer, FIG. Stores the data entered at the location and reads the address information of the last cell (second cell) stored in the corresponding class buffer from the class buffer management table.

Subsequently, based on the address information of the last cell (second cell) read from the class buffer management table, the address of the cell (third cell) stored last in the link list portion of the previously stored cell (second cell) is selected. Write to make a linked list, and change the address information of the last cell stored in the corresponding class buffer from the address information of the second cell to the address information of the third cell.

Finally, the number of cells stored in the class buffer is increased by one.

Meanwhile, the priority control unit 140 extracts and outputs data stored in a class buffer having a high priority according to a preset priority of a class. For example, if the priority is specified in the order of CBR, VBR, ABR, UBR, and extracted from the data stored in the CBR buffer 121, which is a high-priority real-time buffer, and outputs to the CBR buffer 121 When up to the third cell is stored, the address information of the first cell (first cell) stored in the CBR buffer 121 is read from the class buffer management table, and the CBR buffer 121 is read based on the read address information. Read data from the corresponding location of and print it.

Thereafter, the address information of the first cell stored in the CBR buffer 121 is changed to the address information of the second cell recorded in the link list portion of the first cell, and the number of cells stored in the CBR buffer 121 is changed. 1 decreases.

6 is a flowchart illustrating a buffer control method of an ATM switch according to the present invention.

First, a class buffer management table is configured by specifying a class type and a buffer size for each class at system initialization, and a class discrimination table is configured using the class type specified at data channel setting (S10 and S12).

Subsequently, when data is input through a specific data channel set up, the class identification table is searched by the ID of the data channel to which the data is input to find out the class assigned to the data channel, and input based on the found class information. The class buffer in which the data is to be stored is determined (S14, S16). For example, assuming that the class of the first data channel is set to CBR when the first data channel is set, data input through the first data channel is classified as CBR data and stored in the CBR buffer 121. Is determined.

Thereafter, by comparing the buffer size of the class buffer designated in step S16 with the number of data currently stored in the corresponding class buffer, it is determined whether the data input in step S14 can be stored (S18).

If the determination result data of step S18 cannot be stored, the data input in step S14 is discarded (S20).

On the other hand, if the determination result data of step S18 can be stored, the data input in step S14 is stored in an arbitrary place of the corresponding class buffer, and the last stored in the corresponding class buffer in the corresponding class buffer management table. The address information of the data is read (S22, S24).

Subsequently, based on the address information of the last data read in step S24 described above, a link list is created by writing the address of the data last stored in step S22 in the link list portion of previously stored data, and a class buffer management table The address information of the last data stored in the corresponding class buffer stored at is changed to the address information of the data stored at the above step S22 (S26 and S28).

Then, the number of data stored in the corresponding class buffer is increased by one (S30).

The data stored in the corresponding class buffer are output from the data stored in the class buffer determined according to the priority of the preset class through steps S18 through S30. The priority is increased by searching the class buffer management table. It is determined whether the number of data stored in the highest class buffer, for example, the CBR buffer 121 is greater than zero (S32).

As a result of the determination in step S32, when the number of data stored in the highest priority class buffer, for example, the CBR buffer 121 is greater than 0, the class buffer is stored in the corresponding class buffer in the class buffer management table. The address information of the first data is read, and data is read and output from the corresponding position of the corresponding class buffer based on the read address information (S34, S36).

Thereafter, the address information of the first data stored in the corresponding class buffer is changed to the address information recorded in the link list portion of the data output in step S36, and the number of cells stored in the CBR buffer 121 is changed to 1. Decrease (S38, S40).

On the other hand, if the number of data stored in the highest priority class buffer, for example, the CBR buffer 121 is not greater than zero, as a result of the determination in step S32, the next highest priority class buffer, For example, it is determined whether the number of data stored in the VBR buffer 125 is greater than zero (S42).

As a result of the determination of step S42, if the number of data stored in the next-highest priority class buffer, for example, the VBR buffer 125 is greater than zero, the steps S34 to S40 are repeatedly performed. Outputs the data stored in the class buffer and outputs the data stored in the corresponding class buffer through the same process for the remaining classes.

The buffer control apparatus and method of the ATM switch of the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea of the present invention.

According to the buffer control apparatus and method of the ATM switch of the present invention as described above, the class of the input data is distinguished and stored in a buffer divided into classes, and the data stored in the buffer according to the priority of the class. By outputting, real-time traffic can be processed first, thereby satisfying service quality. Then, the buffer resource can be efficiently used.

Claims (9)

A class discriminating unit for classifying a class of data input through the data channel based on a class designated when the data channel is set when data is input through a predetermined data channel; A buffer unit which is divided into a class buffer corresponding to the number of classes, and stores data received from the class discriminating unit in a corresponding class buffer; A buffer control unit for storing the data distinguished by the class in the class discriminating unit in a corresponding class buffer, increasing the number of data stored in the corresponding class buffer by one, and linking the previously stored data using a linked list structure; And a priority control unit configured to extract and store data stored in a high priority class buffer according to a preset priority of the class, and to reduce the number of data stored in the class buffer in which the data is output by one. Buffer controller of ATM switch. The method of claim 1, wherein the buffer unit, A real time buffer unit for storing real time data; A buffer control apparatus of an ATM switch, characterized in that the non-real time buffer unit for storing the non-real time data. The non-real time buffer unit of claim 2, A buffer control apparatus of an ATM switch comprising at least one of a VBR buffer, an ABR buffer, and a UBR buffer. Determining a class buffer in which the received data is to be stored by searching a class discrimination table based on an ID of the data channel when data is input through a predetermined data channel; A storing step of storing the received data in the determined class buffer; And an output process of extracting and outputting data stored in a high priority class buffer according to a preset priority of a class. The method of claim 4, wherein the class distinction table, A data channel ID for which a current channel is set; And a class information designated at the time of data channel setting. The method of claim 4, wherein the storing process, Determining whether the received data can be stored in the class buffer using the buffer size of the class buffer and the number of data currently stored in the class buffer; If it is determined that the received data can be stored in the class buffer, storing the received data in a corresponding area of the class buffer; Reading address information of the last data stored in the class buffer from a class buffer management table; Generating a linked list by recording an address of the stored data in a link list portion of previously stored data based on the read address information; Changing address information of the last data stored in the class buffer to address information of the stored data; And controlling the number of data stored in the class buffer by one. The method of claim 6, wherein the class buffer management table, A buffer size designated for each class type; The number of data stored in the corresponding class buffer; Address information of the first cell stored in the corresponding class buffer; A method of controlling a buffer of an ATM switch, comprising: address information of a last cell stored in a corresponding class buffer. The method of claim 4, wherein the output process, Determining whether data exists in the selected class buffer according to the priority; Reading the address information of the first data stored in the class buffer from the class buffer management table when there is data in the class buffer as a result of the determination; Reading and outputting data from a corresponding area of the class buffer based on the read address information; Changing address information of the first data stored in the class buffer to address information recorded in the link list portion of the output data; And controlling the number of cells stored in the class buffer by one. 10. The method of claim 8, wherein when there is no data in the class buffer as a result of the determination, Outputting the data stored in the next priority class buffer or outputting the data stored in the next priority class buffer according to whether data exists in the next priority class buffer. The buffer control method of the AT switch.