KR19990058286A - Traffic Control Device on Asynchronous Forward Mode Network Nodes - Google Patents

Abstract

The present invention relates to traffic control on a node in an asynchronous transmission mode network. When a traffic jam occurs in a predetermined node, the cell is discarded at a priority level considering the delay limit and the cell discarding rank (CLP) to prevent traffic on the node. It is to provide a traffic control device on an asynchronous delivery mode network node for control. Accordingly, an apparatus according to the present invention includes a cell pool for storing and reading ATM cells on a cell basis; A control unit which analyzes the authorized ATM cell header to extract delay limit and cell abandonment priority information as priority information, and controls traffic of the node; when a new cell is applied, outputs an idle address and, if a congestion occurs, A cell address queue for outputting addresses according to priorities to idle addresses; It stores the information combining the priority information transmitted from the control unit and the address transmitted from the cell address queue according to the priority, and if the cell discard request signal is applied from the control unit, the address of the cell having the highest cell abandonment rank and the lowest delay limit is stored. A priority queue for outputting to a discard address; And a transmission means for transmitting the discard address output from the priority queue to the cell address queue. Therefore, when congestion occurs on a node in the asynchronous transmission mode, the reliability of the traffic control on the node can be improved by further considering that a large value of the delay limit is more likely to be serviced.

Description

Traffic Control Device on Asynchronous Forward Mode Network Nodes

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traffic control device on an asynchronous transfer mode (hereinafter, referred to as ATM) network node, and in particular, to overflow of a buffer due to congestion at an arbitrary node. When is generated, relates to a traffic control device for controlling the traffic on the node with efficient Discard (Discard).

ATM is a communication method that has emerged as a realization of BISDN (Broadband Integrated Services Digital Network). It is a method that integrates the existing line mode digital communication method and packet mode communication method to handle various services in common. have. As such, ATM has the advantage of increasing efficiency and supporting various services simultaneously. However, in order to fully exploit these advantages, traffic control and resource management problems must be solved. To this end, the ATM network controls traffic such as connection admission control, user parameter control, network parameter control, priority control, and congestion control. Provide the ability.

1 is a model diagram of an ATM network resource management using user variable control (UPC). When a cell is sent from the signal sources 101 to 103 through the multiplexer 110, the UPC 120 is connected to the signal sources 101 to 103. FIG. While monitoring whether the call setup contract based on the statistical characteristics presented by each star is being observed, routing or traffic is transmitted to the destination to avoid the congested node among the nodes provided in the communication network 130. To control the flow.

As such, the traffic control method in the ATM network having the UPC 120 may be classified into traffic control at the cell level and traffic control at the call level. Traffic control at the cell level includes user variable monitoring at the UPC 120 and buffer management at each node. Traffic control at the call level includes connection acceptance control and VC path assignment.

In particular, when a buffer is generated to control traffic at the cell level, when a randomization occurs at an arbitrary node, a cell having a lower priority using a cell loss priority bit included in the cell header is used. Traffic was controlled by discarding or passing it through. That is, a cell having a lower priority by the user's designation is transmitted with the CLP bit set to '1'. When a jam occurs in an arbitrary node, the CLP bit of a newly arrived cell is analyzed and set to '1'. If it is set, it is determined that the priority is low and then discarded. If the CLP bit is not '1', it is determined as a high priority cell, and among the cells already stored in the buffer of the node, the low priority cell having the CLP bit is '1' is discarded, and a new arrival cell is created. Serve

However, when solving the jam with this pushout method, the cell is discarded with a priority considering only the CLP bit, so that a cell having a substantially higher priority is discarded. This is because the cells classified as low priority because the CLP bit is set to '1' may be classified again according to whether the delay limit is small or large. That is, a higher delay limit among cells having a lower priority because the CLP bit is set to '1' has a higher priority than a smaller delay limit. However, the conventional method discards the cell by considering only the CLP, so that although the CLP bit is set to '1' and there is a cell with a small delay limit, the cell with the CLP bit set to '1' and the large delay limit is discarded. Phenomenon occurs, which reduces the reliability of traffic control.

The present invention has been made to solve the above-described drawbacks, and when congestion occurs at a given node of an asynchronous transmission mode network, the cell is discarded at a priority level considering the delay limit and the cell abandonment rank (CLP). An object of the present invention is to provide a traffic control device on an asynchronous delivery mode network node for controlling traffic.

In order to achieve the above object, a traffic control apparatus on an asynchronous delivery mode network node according to the present invention, in a traffic control apparatus for a node provided in an asynchronous delivery mode network, stores an asynchronous delivery mode cell applied on a cell basis. A cell pool to read; A controller for analyzing the applied asynchronous delivery mode cell header to extract delay limits and cell discard priority information as priority information and to control traffic of the node; A cell address queue for outputting an idle address if cell arrival information is applied from the control unit and for transmitting information (Empty) that no idle address exists to the control unit if no idle address exists; Stores information combining the priority information transmitted from the control unit and the address transmitted from the cell address queue according to the priority, and outputs the address of the cell having the smallest delay limit when the service request signal is applied from the control unit. A priority queue for outputting an address of a cell having a high cell discard priority and the smallest delay limit to the discard address when the cell discard request signal is applied; The transmission path is controlled by the control unit, characterized in that it comprises a transmission means for transmitting the service address and the discard address output from the priority queue to the cell address queue.

1 is an ATM network resource management model diagram using UPC,

2 is a block diagram of a traffic control apparatus on an asynchronous delivery mode network node according to the present invention.

<Description of the symbols for the main parts of the drawings>

201: controller 202: cell pool

203: Cell address queue 204: Priority queue

205: multiplexer

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram of a traffic control apparatus on an asynchronous delivery mode network node according to the present invention. When the asynchronous delivery mode (hereinafter, referred to as ATM) cell information is applied, FIG. 2 is stored in a designated address area and cell information set in a service address area is shown. Cell output information from the control unit 202 and the control unit 202 for determining the priority by analyzing the output of the cell pool 201, header information of the applied cell, and controlling traffic according to the state of the cell pool 201 Is applied, the priority information of the currently applied cell transmitted from the cell address queue 203 and the control unit 202 generating the write address W_addr of the cell pool 201 according to the address situation of the cell pool 201. Transmission path is controlled by the priority queue 204 and the control unit 202, which stores priority information in units of cells combining the address information provided from the cell address queue 203 and the control unit 202 and is output from the priority queue 204. And a multiplexer 205 for selectively transmitting the service address and the discard address to the cell address queue 203.

In the asynchronous delivery mode network node configured as described above, the traffic control apparatus operates as follows.

First, when predetermined ATM cell information is applied, pure data information is transmitted to the cell pool 201, and cell header information is transmitted to the control unit 202.

When the currently applied cell header is applied, the control unit 202 first transmits cell arrival information to the cell address queue 203, and extracts a delay line (DL) and CLP information from information loaded on the cell header. The priority information is transmitted to the priority queue 204.

The cell address queue 203 outputs an idle address when cell arrival information is applied from the control unit 202. The output address is transmitted to the priority queue 204 and the write address terminal W_addr of the cell pool 201. The cell pool 201 stores the applied cell data at an address applied to the write address terminal.

The priority queue 204 is a priority based on a delay limit of information combining the idle address transmitted from the cell address queue 203 and the priority information transmitted from the control unit 202 (information consisting of a delay limit value and CLP information). Determine and save. This is because, when serving the cell, the delay limit is made in the order of smallest. Therefore, if service is requested from the control unit 202 in a state where no congestion occurs, the address of the cell having the smallest delay limit is transmitted to the read address terminal R_addr of the cell pool 201 and stored at the address. Is read into the serviced cell.

At this time, the service address output from the priority queue 204 is also transmitted to the cell address queue 203 through the multiplexer 205. When a predetermined address is transmitted from the multiplexer 205, the cell address queue 206 holds the transmitted predetermined address as one idle address if an idle address exists. In the multiplexer 205, the transmission path is controlled by the control unit 202. When the service address is output from the priority queue 204 as described above, the input terminal to which the service address is applied is connected to the output terminal.

On the other hand, when the cell address queue 203 transmits a signal (Empty) indicating that the idle address is empty for the cell arrival information sent by the control unit 202 to the control unit 202, the control unit 202 is a priority queue A cell discard request is made at 204.

When cell discard is requested from the control unit 202, the priority queue 204 searches and outputs the address of the cell having the high cell discarding priority bit (CLP = 1) to the multiplexer 205 in the order of the cells with the lowest delay limit. . At this time, the multiplexer 205 is controlled by the control unit 202 so that the input terminal to which the discard address is input is connected to the output terminal. Therefore, the discard address output from the priority queue 204 is transmitted to the cell address queue 203.

Since the idle address does not exist at all when the discard address is applied from the multiplexer 205, the cell address queue 203 outputs the applied address as an idle address. The output addresses are transmitted to the priority queue 204 and the cell pool 201, respectively. Accordingly, the cell pool 201 stores the cell data currently applied at the provided address.

As described above, according to the present invention, when congestion occurs on a node in an asynchronous delivery mode network, the cell is controlled by discarding the cell at a priority level considering the delay limit and the cell discarding priority, so that the cell having a small delay limit when the jam occurs. Considering that a larger cell is more likely to be serviced, there is an effect of improving the reliability of traffic control on the node.

Claims (2)

In the traffic control device for a node provided in the asynchronous delivery mode network, A cell pool for storing and reading the applied asynchronous transfer mode cells on a cell basis; A control unit for analyzing the applied asynchronous delivery mode cell header, extracting delay limit value and cell discard rank information as priority information, and controlling traffic of the node; A cell address queue that outputs an idle address when cell arrival information is applied from the controller, and transmits information (Empty) that the idle address does not exist to the controller when the idle address does not exist; Stores the combined information of the priority information transmitted from the control unit and the address transmitted from the cell address queue according to the priority, and outputs the address of the cell having the smallest delay limit when a service request signal is applied from the control unit. And a priority queue for outputting an address of a cell having a high cell discarding rank and the smallest delay limit as a discard address when a cell discard request signal is applied from the controller. And transmission means for transmitting the service address and the discard address output from the priority queue to the cell address queue by the control unit by the control unit. The cell address queue of claim 1, wherein when the discard address is applied from the transmitting means, the cell address queue outputs the applied discard address to the priority queue and the cell pool, respectively. And if a service address is applied, holding the authorized service address as an idle address.