KR0153925B1 - Method of intelligent cell discarding in atm switching system - Google Patents

Abstract

The present invention provides a VPI / VCI (Virtual Path Identifier) in a cell header when providing an ABT service.

The intelligent cell closure method in an asynchronous delivery switch that quickly eliminates the overload condition generated by using the / Virtual Channel Identifier value and efficiently uses the wasted bandwidth. A first step of checking whether it has been exceeded or if the current exchange is overloaded; A second step of determining whether a cell is in communication or an ongoing service is ABT according to the cell entry rate or an overload state of a current exchange; And the third step of tagging or discarding the corresponding cell if the ongoing service is not the ABT service and releasing the circuit connection or discarding the corresponding block if the ABT service is the ABT service. High effect can be expected to prevent and eliminate overload.

Description

Intelligent Cell Closure Method in Asynchronous Transfer Exchange

1 is a general cell waste processing flow chart.

2 is a processor architecture diagram of an ATM switch to which the present invention is applied.

3 is a flowchart of an intelligent cell disposal process according to the present invention.

* Explanation of symbols for main parts of the drawings

210: Central Switching Subsystem (ACS)

211: Interconnect Switch Network Module (ISNM)

212: operation maintenance processor (OMP) 220: connection exchange subsystem (ALS)

221: connection exchange network module (ASNM) 222: call connection processing processor (CCCP)

230: interworking exchange subsystem (IWS / S) 231: interworking processor (IWP)

232: analog matching processor (AASP)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intelligent cell closure method in an asynchronous transfer method (hereinafter referred to as ATM) exchange, and in particular, an overload state generated by using a VPI / VCI (Virtual Path Identifier / Virtual Channel Identifier) value in a cell header when providing an ABT service. It is a smart cell closure method in an ATM switch that can quickly solve the problem and efficiently use the wasted bandwidth.

In general, when a transmitted cell enters the User Parameter Control (UPC) point, if the cell entry rate negotiated at call setup is exceeded or if an overload occurs in the exchange, the exchange is in network service. In order to guarantee the negotiated performance of the call, the lower priority cell is unconditionally discarded based on the Cell Loss Priority (hereinafter referred to as CLP) of the cell header. To be discarded or tagged.

1 is a flow chart of a general cell closure process, which is a user parameter control (UPC) point when the cell entry rate exceeds the negotiated cell entry rate, or when the exchange is overloaded, In order to guarantee the overall efficiency of the network, there is a function of discarding cells, such as UPC function in the pressurized cluster and priority control in the switch.

The UPC function checks whether the subscriber is transmitting a cell in compliance with the transmission cell rate agreed upon between the subscriber and the service provider when setting up a call. The cells are discarded and the cells passing through the UPC point go through Network Parameter Control (NPC) in the same way as UPC during the exchange.

The priority control is a function that eliminates the overload by discarding the cells passing through the switch when the corresponding switch is overloaded when the cell passes through the switch inside the exchange.

This cell waste operation occurs as follows.

As shown in FIG. 1, when a cell transmitted from a transmitter enters (101), the subscriber station checks the cell entry rate and checks whether the current state is overloaded when passing through the switch (102). Pass the cell if the rate is not exceeded and not overloaded (103), and if the cells enter or exceed the agreed cell entry rate at call setup, or if the exchange is overloaded, read the CLP bit in the header of the excess cells (104).

Since the CLP value of the cell header indicates a high rank when 0 and a low rank when 1, when a cell having a high rank exceeds an entry rate, it is tagged or discarded according to the definition of call setup (106). If a low rank cell enters, it is immediately discarded (107).

If the tagged cell is subjected to congestion again, the tagged cell is treated the same as the lower rank cell.

ABT (Full Name ????) service combines cells to be transmitted into several frames, and efficiently uses bandwidth by transmitting data in units of frames at a time when circuit utilization is low.

These ABT services are mainly used for data transfer and are divided into ABT / DT (Delayed Transfer) and ABT / IT (Immediate Transfer). The former can be somewhat delayed but very sensitive to loss. It is used for a service that bundles a small number of cells in time and transmits them together.

In the case of such a data transmission service, if only one of the cells is lost, the remaining cells are likely to lose value as information.

That is, if only a few of the cells belonging to the ABT service are discarded, the remaining cells other than the cells that are lost continuously until the situation is resolved will be allocated to the bandwidth and sent to the destination. .

As a result, the cell-based discarding method has a problem of slowing down the overload resolution time of the exchange itself and wasting bandwidth for transmission of meaningless cells.

In order to solve the problems of the prior art as described above, in the case of ABT service, when one cell is discarded, all of the corresponding cells are discarded in series to quickly eliminate an overload condition and waste bandwidth. The purpose of the present invention is to provide an intelligent cell dispensing method in an ATM exchange system that can efficiently use the ATM.

The present invention for achieving the above object, the Central Switching Subsystem (ATM Central Switching Subsystem) (hereinafter referred to as ACS) that performs the overall system maintenance, and the Connection Exchange Sub connected to the ACS to perform a user access service Interworking Switching Subsystem / Analog Subscriber (hereinafter referred to as ALS) and an ALS connected to the ALS to match an analog subscriber to a Broadband Telecommunication Network (B-ISDN). An intelligent cell closing method applied to an ATM switch having an IWS / S), the method comprising: a first step of checking whether a cell entry rate has been exceeded or a current switch is overloaded when a cell enters; A second step of determining whether a cell is in communication or an ongoing service is ABT according to the cell entry rate or an overload state of a current exchange; As a result of the determination, if the ongoing service is not an ABT service, a third step of tagging or discarding the corresponding cell and disconnecting the circuit connection or discarding the corresponding block is the ABT service.

That is, according to the present invention according to the above process, when a cell transmitted at the UPC point has exceeded cell entry or has to discard one cell due to an overload of a switch, the cells belonging to the ABT service discard the entire block or discard the corresponding ABT service. By releasing the circuit set to provide, the overload condition generated can be quickly eliminated, and the wasted bandwidth can be efficiently used.

In this case, to distinguish between cells belonging to the same service, a VPI / VCI (Virtual Path Identifier / Virtual Channel Identifier) value in the cell header is used.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

2 is a processor structural diagram of an ATM switch to which the present invention is applied, and the ATM switch has a hierarchical structure of subsystems, modules, and blocks.

As shown in the figure, the subsystem includes an ATM Central Switching Subsystem (hereinafter referred to as ACS) 210 and an ATM Local Switching Subsystem (hereinafter referred to as ALS) 220; There are three kinds of interworking switching subsystem (Interworking Switching Subsystem / Analog Subscriber: hereinafter referred to as IWS / S) 230.

In the ACS 2210, an interconnection switch network module (hereinafter referred to as ISNM) 211 performs overall system maintenance, and the ALS 220 includes an access switch network module (Access Switch Netwoek). Module (hereinafter referred to as ASNM) 221 performs a user access service, each function being processed by blocks composed of processors.

First, an Operation & Maintenance Processor (hereinafter referred to as OMP) 212 is connected to the ISNM 211 of the ACS 210 to restart the system, control operations, test, subscriber management, system resource management, and the like. A call connection processing processor (hereinafter referred to as CCCP) 222 is connected to the ASNM 221 of the ALS 220 so as to perform a higher subscriber call processing function, a higher relay line call processing function, and a signaling method. Handles processing functions, maintenance functions, etc.

The upper subscriber / relay line call processing function includes Call Admission Control (CAC), VPI / VCI (Virtual Path Identifier / Virtual Channel Identifier) assignment, number input, switch path selection, and the like. Examples include signal message flow control and signal message transmission error detection and recovery.

In addition, the IWS / S 230 matches an analog subscriber to a broadband integrated information network (B-ISDN), an interworking processor (hereinafter referred to as IWP) 231 and an analog matching processor (Analog Access Switching). Processor (hereinafter referred to as AASP) 232 is responsible for this.

The AASP 232 is the IWS / S 230 performs the overall control of the internal call control, maintenance, etc., the IWP 231 is the internal IPC (Inter) of the CCCP (222) and AASP (232)

Processor Communication) Message matching and digitized voice information are cellized and the multi / demultiplexer is controlled.

FIG. 3 is an intelligent cell discard processing flow chart in accordance with the present invention, which reads the VPI / VCI when discarding a cell and if the current service is ABT, discards all associated cells regardless of the CLP bit.

As shown in the figure, when the cell enters (301), the cell entry rate is exceeded or is overloaded (302), the cell entry rate is not exceeded and passes through the cell if not overloaded (303) If the cell entry rate exceeds the negotiated rate or the current exchange is overloaded, the VPI / VCI of the cell is read (304).

The ongoing service is read according to the read information of the VPI / VCI (305), at which time it is determined whether the pinned service is ABT (306). If it is not an ABT service, the CLP bit of the corresponding cell is checked (307). If it is 0, it is tagged or discarded (308).

If the read service is an ABT service, it is determined whether it is an ABT / DT service or an ABT / IT service (310). If the ABT / DT is used, the circuit connection is released (311). If the ABT / IT service is used, the corresponding block is discarded (312). .

The discarding of the corresponding block is performed by discarding all cells entering with the same VPI / VCI value, and this operation is released at the moment of identifying a cell having another VPI / VCI.

According to the above, the present invention can be expected to have a high effect on the overload prevention and resolution of the area mainly using data services.

Claims (4)

A central switching system (ATM Central Switching Subsystem) (hereinafter referred to as an ACS) 210 that performs overall system maintenance, and an Access Switching Subsystem (ATM Local) connected to the ACS 210 to perform a user access service. Switching Subsystem (hereinafter, referred to as ALS) 220 and an Interworking Switching Subsystem (Aworking Switching Subsystem / Analog Subscriber) connected to the ALS 220 to match an analog subscriber with a Broadband Telecommunication Network (B-ISDN): An intelligent cell dispensing method applied to an ATM exchanger having an IWS / S), comprising: a first step of checking whether a cell entry rate is exceeded or a current exchange is overloaded when a cell enters; A second step of determining whether a cell is in communication or an ongoing service is ABT according to the cell entry rate or an overload state of a current exchange; And a third step of tagging or discarding the corresponding cell if the ongoing service is not the ABT service and releasing the circuit connection or discarding the corresponding block if the ABT service is the ongoing service. Intelligent cell waste method. 2. The method of claim 1, wherein the second step comprises: a fourth step of, after performing the first step, calling a cell if the cell entry rate does not exceed an agreed rate and the current exchange is not overloaded; A fifth step of reading a VPI / VCI (Virtual Path Identifier / Virtual Channel Identifier) of the cell when the cell entry rate exceeds the agreed rate or the current exchange is overloaded after performing the first step; And a sixth step of determining an ABT service by reading an ongoing service according to the read information of the VPI / VCI. The method of claim 1, wherein the third step comprises: after performing the second step, checking a cell loss priority (CLP) bit of a corresponding cell if the ongoing service is not an ABT service; ; Tagging or discarding if the CLP bit is a predetermined bit and discarding if the CLP bit is a predetermined bit; A sixth step of determining whether an ongoing service is an ABT / Delayed Transfer (ABT / DT) service or an ABT / IT (Immediate Transfer) service after performing the second step; And a seventh step of releasing the circuit connection if the ABT / DT is determined and discarding the corresponding block if the ABT / IT is determined as the determination result. 4. The asynchronous method of claim 3, wherein the discarding of the corresponding block in the seventh step discards all the cells entering with the same VPI / VCI value and is released at the moment of identifying the cell having the different VPI / VCI. Intelligent Cell Closure Method in Delivery Exchanges.