KR0133800B1 - A circuit for arbitrating between aal types in an atm card - Google Patents

Abstract

The present invention relates to an AAL arbitration circuit of an asynchronous mode (ATM) access card, comprising: an associated memory 50 capable of processing a predetermined number of data matching by storing and storing a predetermined number of VPI / VCIs from an ATM layer 60; ; A plurality of buffers 14 for storing received data according to AAL type 1; A plurality of buffers 35 for storing received data according to AAL type 5; A plurality of AND gates 71 to 86 for enabling the corresponding buffers 14, 25 and 35 by inputting the data start clocks from the ATM layer 60 and the match signals M1 to M16 from the associated memory 50; Mediate the AAL type at high speed according to the received VPI / VCI of the ATM cell.

Description

AI arbitration circuit of asynchronous mode access card

1 is a schematic diagram for explaining a general ATM communication method, (A) is a diagram showing an ATM cell,

(B) shows a header at the time of a user network connection (UNI), (c) shows a header at the time of a network node connection (NNI),

2 is a block diagram showing a workstation ATM access card apparatus to which the present invention is applied.

3 is a circuit diagram showing an AAL arbitration circuit according to the present invention;

4 is an example of the associative memory shown in FIG.

* Description of the symbols for the main parts of the drawings *

1: SBUS interface 2: ATM multiplex controller,

3: ATM header transmission processing unit 4: Transmission terminal adapter

5: receiver terminal adapter 6: ATM header receiver,

7: AAL arbitration circuit 9: B-ISDN (ATM network),

10: AAL type 1 transceiver

12,15,13,14,23,25,25,26,33,34,35,36: FIFOs (buffers)

11: AAL type 1 SAR processing unit 20: AAL type 3/4 transmission / reception processing unit

21: AAL 3/4 CPCS processing unit 22: AAL 3/4 SAR processing unit,

30: AAL 5 transmission and reception processing unit 31: AAL 5 CPCS processing unit,

32: AAL 5 SAR processing unit

The present invention relates to an ATM access card apparatus mounted on a workstation to connect an Asynchronous Transfer Mode (ATM) network and a workstation.

In general, an ATM communication method is a method of communicating by dividing and reassembling a long message into 53-byte cells as a basic unit, as shown in FIG. 1A. An ATM cell has a 5-byte header (H: Header). Section and a 48-byte user information section, and the 5-byte header consists of a header structure and a network node in the User Network Interface (UNI) as shown in FIG. 1 (b) and (c). It is divided into header structure in NNI (Network Node Interface), and header structure in user network interface (UNI) is that the first byte has 4 bits of Generic Flow Control (GFC) and 4 bits of virtual path. It consists of an identifier (VPI: Vertual Path Identifier), the second byte consists of a 4-bit virtual path identifier (VPI) and a 4-bit virtual channel identifier (VCI), and the third byte is an 8-bit Virtual channel identifier (VCI), and the fourth byte It consists of a 4-bit virtual channel identifier (VCI), a 3-bit payload type (PT) and a 1-bit cell loss priority (CLP), and the fifth byte is an 8-bit header error control. (HEC: Header Error Control).

Here, the last bit of the 3-bit payload type is a user bit (AUU: ATM USER TO ATM USER), which is useful in the AAL 5 protocol. When the first bit is 1, the operation type of OAM (Operation, Administration, and Management) and the general meaning is as follows [Table 1].

Table 1

In addition, when looking at the header structure of the network node interface (NNI), the general network control (GFC) in the first byte of the user network interface (UNI) described above is used as the virtual path identifier (VPI). It can be seen that the header structure of the contact surface (NNI) is the same.

This ATM communication system has a hierarchical structure as shown in [Table 2], and has standardized standards for each layer.

[Table 2]

As shown in [Table 2], the ATM communication method is divided into vertical structures such as a physical layer, an ATM layer, an ATM adaptation layer (AAL: ATM adaptation layer), and a higher protocol layer. It is divided into Segmentation And Reassembly Sublayer (SAR) and Convergence Sublayer (CS) sublayer, and the physical layer is divided into Physical Media (PM) and Transmission Convergence (TC) sublayer.

In addition, according to the service of the user, that is, the characteristics of the source in the ATM communication method can be separated as shown in Table 3 below.

Table 3

As shown in Table 3, the types of services in B-ISDN are classified into Classes A to D according to the nature of the source. The Class A services are real-time, identity bit rate, and connectivity services. It is a variable bit rate, connectivity service, Class C service is a non-real time, variable bit rate, a non-connected service, Class D service is a non-real time, variable bit rate, a non-connection.

Meanwhile, AAL protocols corresponding to the above services are classified into AAL1 to AAL5 as shown in the following [Table 4]. Conventionally, AAL1 to AAL4 are classified into AAL1 to AAL4. However, AA3 and AAL4 are similar to each other. AAL5 has been proposed which reduces overhead for data communication.

Table 4

As shown in [Table 4], the AAL layer is horizontally divided into AAL1, AAL2, AAL3 / 4, and AAL5 in order to efficiently process the corresponding service according to the type of service.

According to the technical development for implementing the ATM network as described above, it is necessary to connect the workstation to the ATM network for communication according to the ATM method, but there is no device that satisfies these requirements.

In addition, since there is no AAL type in the ATM communication terminal, there is no need to implement the AAL arbiter, and the analysis method of VPI / VCI is used to decode 24-bit VPI / VCI, but it is used for logic. The number of gates to be used has a complicated problem in the circuit.

Accordingly, an object of the present invention is to implement the ATM access card device to solve the above-mentioned conventional problems, by implementing the AAL mediation device used to service a variety of AAL types as one card device as an associated memory An AAL arbitration circuit is provided to enable processing.

The AAL arbitration circuit of the present invention for achieving the above object, AAL arbitration of the ATM access card to connect the ATM network and the workstation and mediate the received ATM cell to the VPI / VCI to support services according to various AAL types 1. A circuit comprising: an associated memory capable of processing a predetermined number of data matches by inputting and storing up to a predetermined number of VPI / VCIs from an ATM layer; A plurality of buffers 14 for storing different received data in AAL type 1; A plurality of buffers 25 for storing received data according to AAL type 3/4; A plurality of buffers 35 for storing received data according to AAL type 5; And a plurality of AND gates 71 for inputting data from the ATM layer 60 to the start signals and the match signals M1 to M16 from the associated memory 50 to enable the corresponding buffers 14, 25, and 35. To 86).

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

2 is a block diagram showing an ATM access card to which the present invention is applied, comprising: a SUBS interface unit 1 for interfacing with an SBUS which is an input / output bus of a sun workstation; A transmission terminal adapter 4 for transmitting the ATM cell to the ATM network 9; A receiving terminal adapter 5 for receiving the ATM cell from the ATM network 9; AAL type 1 transmit / receive processing section 10 for inputting transmission data from the input / output bus 1, processing it according to AAL type 1, outputting the data in 48-byte units, and combining the received 48-byte cell data to the input / output bus. ; AAL type 3 that inputs the transmission data from the I / O bus (1), processes it according to AAL type 3/4, outputs it in 48-byte units, and combines the received 48-byte unit data and outputs it to the I / O bus (1). / 4 transmission and reception processing unit 20; AAL type 5 transmit / receive processing section for inputting transmission data from the input / output bus (1), processing it according to AAL type 5, outputting it in 48-byte units, and combining the received 48-byte cell data to the input / output bus (1). 30: input 48-byte data from the AAL type 1, 3/4, 5 transmit / receive processing unit, add a 5-byte header, output 53-byte ATM cells to the transmit terminal adapter 4, and receive An ATM processor 60 which receives a 53-byte ATM cell from the terminal adapter 5, processes a 5-byte ATM header separately, and outputs data in units of 48 bytes; An ATM multiplex control unit (2) which arbitrates transmission between AAL type 1, 3/4, and 5 transmission / reception processing units; And an ATM arbitration circuit 7 which arbitrates reception between AAL type 1, 3/4, 5 transmission / reception processing units.

Here, the transmitting terminal adapter 4 is implemented as a transmitting TAXI chip, and the transmitting TAXI chip converts data into optical fibers so that the data can be transmitted through an optical cable, and the data transmitted through the optical cable is a receiving terminal adapter implemented as a receiving TAXI chip. Received by (5) and delivered to the ATM header receiving processing section (6).

3 is a circuit diagram of an AAL arbitration circuit according to the present invention, in which ATM cells received from the B-ISDN network 9 through the physical layer 65 are separated from the ATM header at the ATM layer 60 to obtain VPI / VCI. After separating, using the associated memory to quickly arbitrate the reception according to the AAL type, the AAL arbitration circuit 7 according to the present invention inputs and stores a predetermined number of VPI / VCI from the ATM layer 60 to a predetermined number. An associated memory (50) capable of processing data matching of a plurality of buffers: a plurality of buffers (14) for storing received data according to AAL type 1; A plurality of buffers 25 for storing received data according to AAL type 3/4; A plurality of buffers 35 for storing received data according to AAL type 5; A plurality of AND gates 71 to 86 for inputting data signals from the ATM layer 60 and matching signals M1 to M16 from the associated memory 50 to enable the corresponding buffers 14, 25 and 35. It is composed of

Subsequently, the operation of the ATM access card to which the present invention configured as described above and the arbitration circuit of the present invention operate will be described in detail by dividing into transmission and reception.

1. Transmission operation description: The sun workstation equipped with the ATM access card according to the present invention sends down the AAL layer through the SBUS interface 1 in order to transmit the multimedia data through the ATM network. In this case, it is necessary to select an appropriate AAL type according to the nature of the data to be transmitted. For example, in order to transmit video data requiring real-time processing, a service according to AAL type 1 is required, and for signal processing In order to transmit a message, service according to AAL type 5 is required, and in order to transmit text, graphics, and script, service according to AAL type 3/4 is required.

The AAL type 1 transmit / receive processing section 10 divides a user's message stored in the transmission FIFO 12 into a flow path load of 47 bytes in the AAL type 1 SAR processing section 11, and then adds a 1-byte SAR header to transmit FIFO ( 13) to the ATM layer.

The AAL type 3/4 transmit / receive processing unit 20 adds a CPCS header and a CPCS trailer from the AAL 3/4 CPCS processing unit 21 to the AAL 3/4 CPCS processing unit 22 by sending the user's message stored in the transmission FIFO 23. The AAL 3/4 SAR processor 22 inputs the output of the AAL 3/4 CPCS processor 21 and divides the payload into 44-byte payloads to divide the 2-byte SAR header and the 2-byte SAR trailer. After the addition, the transmission is transmitted to the ATM layer through the transmission FIFO 24.

The AAL type 5 transmit / receive processing unit 30 sends the user's message stored in the transmission FIFO 33 to the AAL 5 SAR processing unit 32 by adding a pad and a 4-byte CPCS trailer to the AAL 5 CPCS processing unit 31, The 5 SAR processing unit 32 inputs the output of the AAL 5 CPCS processing unit 31, divides each of them into payloads of 48 bytes, and transmits them to the ATM layer through the transmission FIFO 34.

When the ATM multiplex control unit 2 inputs a transmission request signal from the AAL type 1, 3/4, 5 transmission / reception processing units 10, 20, 30, the predetermined priority (typically, type 1 type 3/4 type 5 order) is applied. Enable the corresponding transmission FIFO so that the ATM header transmission processing section 3 reads it, and the ATM header transmission processing section 3 adds 5 bytes of the ATM header to the 48-byte payload, and adds 5 bytes. After the ATM cell is formed, it is transmitted to the ATM network 9 through the transmission terminal adapter 4.

2. Description of Receiving Operation: As described in (b) of FIG. 1, 53-byte ATM cells received from the ATM 9 are virtually connected by 24-bit VPI / VCI to establish a data path. The ATM header receiving processor 6 separates the 5-byte header from the ATM cell received through the receiving terminal adapter 5, and sends the VPI / VCI to the AAL arbitration circuit 7 to check whether there is a header error. The payload of bytes is written to the reception buffer selected by the AAL arbitration circuit 7. At this time, the AAL arbitration circuit 7 compares the preconfigured VPI / VCI and the received VPI / VCI, and enables a matching receiving buffer to arbitrate reception.

Subsequently, the SAR processing unit 11 of the AAL 1 transmitting / receiving processing unit separates the SAR header from the 48-byte data stored in the receiving buffer 14 and checks whether there is an error, assembles pure data, restores the message, and then receives the receiving FIFO (15). The AAL3 / 4 transmit / receive processing unit 20 separates the 2-byte SAR header and 2-byte SAR trailer from the 48-byte data stored in the receiving buffer 25 by the SAR processing unit 22. After restoring the message by assembling the pure data and restoring the message, the message is sent to the CPCS processing unit 21, and the CPCS processing unit 21 separates the 4-byte header, the pad and the 4-byte trailer, and checks the error. Send to the workstation via FIFO (26).

The AAL 5 transmit / receive processing unit 30 assembles 48 bytes of data stored in the reception buffer 35 from the SAR processing unit 32, restores the message, and uploads the data to the CPCS processing unit 31. The CPCS processing unit 31 pads the data. After separating the CPCS trailer with 4 bytes, the error is checked and transmitted to the workstation through the Fisher FIFO 36.

After receiving the necessary data through the S-bus interface unit 1, the sun workstation decodes and displays the video data, and in the case of text data, stores the data in a file.

On the other hand, the AAL mediation apparatus 7 used in the ATM access card apparatus of the present invention discriminates VPI / VCI in the ATM cell at high speed to distinguish the cell transmitted to itself, and which type of AAL the transmitted cell belongs to. The control signal is generated so that the data can be transmitted to the reception FIFO of the corresponding AAL type. At this time, in order to quickly determine which AAL type the received VPI / VCI belongs to, an embodiment of the present invention uses an associative memory.

A general associated memory used in the present invention is a mask register 51, a storage array 52, a match register 53, an MDR register 54, a memory controller 55, an segment register as shown in FIG. It consists of 56 and stores 16 data cells.

When the memory data size is implemented in 32 bits as in general memory, the storage array 52 of the associated memory has 16 32-bit memory areas, and stores the desired 32-bit data value in the storage memory. Sixteen storage arrays 52 used in an embodiment of the present invention store six VPI / VCIs for AAL Type 1, six VPI / VCIs for AAL Type 3/4, and store AAL Type 5 Four VPI / VCIs are stored. The segment register 56 is a 32-bit register having a VPI / VCI value input from the ATM header receiving processor 6, and the mask register is a desired value (that is, 32 bits). Mask only the necessary portion of the memory length. For example, you can mask to ignore the value of the top 8 bits of the 32 bits.

If the VPI / VCI values in the segment register 56 are equally compared by comparing the values in the storage array 52 via the mask register 51, the match register 53 bits of the corresponding storage array 52 are equal. Is counted as 1. For example, when a value of 0 to 15 is stored in the 32-bit storage array 52, and 24 bit VPI / VCI is input to the segment register 56 with a value of 14, the mask register 51 By comparing the mask value of the upper 8 bits with the values in the 16 storage arrays 52 simultaneously, the bits of the 15th match register having a value of 14 are counted and output 1, and the matched value 14 is the MDR register 54. )

As such, when the VPI / VCI value input from the ATM header receiving processor 6 is matched with the VPI / VCI value stored in the associated memory, the match register is set and 1 is output. According to the start clock output from the ATM layer, the output is high to enable the corresponding receiving buffer to store the received cell data.

As described above, the present invention can be used in an integrated ATM access card of a workstation to provide services according to AAL Type 1, AAL Type 3/4, and AAL Type 5 with a single card, thereby improving communication reliability and cost. In particular, it is possible to arbitrate at high speed by using associative memory.

Claims (1)

In the AAL arbitration circuit of an ATM access card that arbitrates a received ATM cell to VPI / VCI to connect an ATM network and a workstation and support services according to various AAL types, a predetermined number of VPI / VCIs are received from the ATM layer 60. Associative memory (50) capable of storing branch inputs and processing a predetermined number of data matchings; A plurality of buffers 14 for storing received data according to AAL type 1; A plurality of buffers 25 for storing received data according to AAL type 3/4; A plurality of buffers 35 for storing received data according to AAL type 5; A plurality of AND gates 71 to 86 for inputting the data start clock from the ATM layer 60 and the match signals M1 to M16 from the associated memory 50 to enable the corresponding buffers 14, 25 and 35. AAL arbitration circuit of the asynchronous mode (ATM) connection card, characterized in that it comprises a.