KR0123227B1 - Transmission interface device of AAL layer - Google Patents

Abstract

The present invention relates to a transmission interface device of the AAL layer, and a register for storing control information. 10; The register by inputting a predetermined address (Add) and a bus control (AS) signal A decoding unit 20 for enabling 10; The register is generated by generating a predetermined address (Add) and a bus control (AS) signal. The control information is stored in (10), and an acknowledgment (ACK) signal is received and registered. This normally A host computer 2 which recognizes that it is loaded; And an acknowledgment signal generator 30 for delaying the output of the decoder 20 to generate an acknowledgment (ACK) signal so that the host computer which is the upper layer is a register of the AAL layer. Control information in Through the acknowledgment signal You can see that the.

Description

Transmission interface device of AAL layer

1 is an example showing the configuration of an entire system to which the present invention is applied.

2 is a block diagram showing an interface device between a higher layer and an AAL layer in transmission according to the present invention.

3 shows the structure of a typical ATM cell.

(a) is a diagram showing the structure of the entire ATM cell.

(b) is a diagram illustrating an ATM cell header structure of a user network interface (UNI).

(c) shows the ATM cell header structure of the network node interface (NNI).

* Explanation of symbols for main parts of the drawings

1,1-1,1-2: I / O bus (SBUS) 2,2-1,2-2: Line workstation

4-1,4-2: ATM communication board 6: ATM switch

7: optical transmission path 10: register

20: decoding unit 22: address decoder

24, 32: Oagate 30: Acknowledgment signal (ACK) generating unit

31,33,34: flip flop

The present invention relates to an interface at the time of transmission between a higher user service layer and an ATM adaptation layer (AAL) in an asynchronous transfer mode (ATM) communication. The present invention relates to an interface device for transferring various control information from an upper layer to an AAL layer by using a s.

Recently, as the means of communication has been rapidly digitalized and the development of optical communication enables transmission of a wide band, broadband ISDN (Broadband Integrated Services Digital Network) has emerged to meet various user's service needs.

That is, B-ISDN is a video telephony and video conferencing service from narrowband services such as remote meter reading, data terminal, telephone, and facsimile as described in broadband information communication (co-author Lee Byung-ki, Kang Min-ho, Jong-hee Lee; Kyohaksa; 1994; Seoul; p239 ~ 314). It is designed to handle and deliver broadband services such as high speed data transmission, video signal transmission, etc. in common, and is implemented based on the asynchronous transmission mode (ATM) communication method.

The ATM communication method is similar to the conventional packet communication method in that ATM cells are transmitted by cell unit by Asynchronous Time Division Multiplexing (ATDM). It handles even signal of bit rate and is standardized by international standardization organization for use in local area network as well as huge public network.

This ATM communication method communicates based on ATM cells as shown in (a) to (c) of FIG. 3, where a user's long message is divided into ATM cells and transmitted, and the received ATM cells are again one message. Is reassembled and forwarded to the parent user.

That is, as shown in (a) of FIG. 3, an ATM cell is divided into a 5-byte (or octet) header section and a 48-byte user information section, and the 5-byte header is divided into (b) and (3) of FIG. As shown in c), the header structure is divided into a header structure at the user network interface (UNI) and a header structure at the network node interface (NNI) and a header structure at the user network interface (UNI). The first byte consists of 4 bits of Generic Flow Control (GFC) and the 4 bytes of Virtual Path Identifier (VPI), and the second byte consists of 4 bits of Virtual Path Identifier ( VPI) and 4-bit Virtual Channel Identifier (VCI), the third byte consists of 8-bit Virtual Channel Identifier (VCI), and the fourth byte is a 4-bit Virtual Channel Identifier (VCI). (VCI), 3-bit payload type (PT: Payload Type) and 1-bit cell abandonment ranking (CLP: Cell Loss Priority, and the fifth byte consists of 8-bit header error control (HEC).

Also, when looking at the header structure of the network node interface (NNI) as shown in FIG. 3 (c), the general flow control (GFC) in the first byte of the user network interface (UNI) described above identifies the virtual path. It can be seen that it is the same as the header structure of the user interface (UNI) except that it is used as a number (VPI).

This ATM communication method has a hierarchical structure as shown in Table 1 below, and has standardized standards for each layer.

As shown in Table 1, the ATM communication method is divided into vertical structures such as a physical layer, an ATM layer, an ATM adaptation layer (AAL), and a higher protocol layer. Sublayer, and the physical layer is subdivided into physical media (PM) and transmission convergence (TC) sublayers.

In addition, the services required by the user in the ATM communication method can be separated according to the characteristics of the source as shown in Table 2 below.

As shown in Table 2, the types of services in the B-ISDN are classified into Classes A to D according to the characteristics 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-connected service. Representative examples of such services include identity rate video signals, variable rate video signals, connectivity data transmission, and connectionless data transmission.

On the other hand, AAL protocols corresponding to the above services are classified into AAL1 to AAL5 as shown in Table 3 below. Conventionally, AAL1 to AAL4 are classified into AAL1 to AAL4. However, AAL3 and AAL4 are similar to each other. AAL5 has been proposed to reduce the overhead.

As shown in Table 3, the AAL layer is divided horizontally as AAL1, AAL2, AAL3 / 4, AAL5 in order to efficiently process the service according to the type of service, and the AAL3 / 4 layer has a variable bit rate. It has the function of delivering data of class C and class D service. It has message mode and stream mode, and transparently delivers service data unit (U-SDU) from service user, detects transmission error, identifies information and A convergence layer layer CS performing a buffer allocation function; Variable length data received from the convergence sublayer (CS) is divided into ATM cells, which are then transmitted to the ATM layer. The ATM cells are received from the ATM layer and subdivided into a recombination and recombination sublayer (SAR).

In addition, the convergence (CS) sublayer includes a common part convergence sublayer (CPCS) that performs functions common to the connected and disconnected services, and a service-specific convergence sublayer (CPCS) for providing a specific AAL user service. SSCS: Service Specific Convergence Layer).

Details of this AAL layer have been proposed in ITU-T Recommendations 1.362 and 1.363, and by Gigabit Networking; Craig Partridge; 1994; Addison Wesley; pp 61–87, by Craig Partidge. And Lee Byung-ki and two others co-authored broadband information communication (pp314 ~ 327).

On the other hand, since the AAL layer as described above is conventionally implemented in software, there is a problem in that the interface processing speed is delayed when transmitting from the upper layer to the AAL layer, and it is necessary to transmit control information separately from general data to be transmitted. there was.

Accordingly, an object of the present invention is to register the control information from the upper layer to the AAL layer in order to solve the problem of the conventional problem as described above and satisfy the necessity. It is to provide an interface device for transmitting using.

Register to store control information and; The register by inputting a predetermined address (Add) and a bus control (AS) signal Decoding unit for enabling the; The register is generated by generating a predetermined address (Add) and a bus control (AS) signal. Control information is stored in the register, and an acknowledgment (ACK) signal is received and registered. This normally A host computer that recognizes that it is loaded; And an acknowledgment signal generator for delaying the output of the decoder to generate an acknowledgment (ACK) signal, wherein the host computer, which is the upper layer, registers an AAL layer. Control information in Through the acknowledgment signal It is characterized by the fact that it can be checked.

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

1 shows an example of the configuration of the entire system to which the present invention is applied, and includes a plurality of line workstations 2-1 and 2-2 as host computers; ATM communication boards 4-1 and 4-2 connected to the line workstations 2-1 and 2-2 to provide communication according to an ATM method; An ATM switch 6 for forming a communication path between the ATM communication boards 4-1 and 4-2 is provided so as to exchange data at high speed between the line workstations according to the ATM communication method.

That is, when the application process of the sun workstation 2-1, which is the host computer of the upper layer, wants to transmit data to the other sun workstation 2-2, the data to be sent is determined according to the characteristics of the source. Data or computer data, etc.) Select the appropriate protocol (ie AAL1, AAL3 / 4, AAL5) to send a message through the I / O bus (SBUS: 1-1) to the AAL layer.

The AAL layer of the ATM communication board 4-1 inputs a message through an input / output bus (SBUS), divides the message into ATM cells as described above, and sends the message down to the ATM layer with various control information. The cell is transmitted to the ATM switch 6 using the optical transmission path 7 of the physical layer, and then through the physical layer and the ATM layer of the communication board 4-2 along the path formed by the ATM switch 6. Reach the opposite AAL layer. The ATM exchange and communication path setting are described in detail in the ATM Switching Technology Special Issue, Vol.19 No.8 (August 92).

On the other hand, the counterpart AAL layer reassembles the received ATM cell data into one message, checks the CRC and sequence number, and checks whether an error occurred during transmission. When the assembly of the received message is completed, the I / O bus (SBUS: 1-2) is interrupted to notify the sun workstation 2-2, which is the upper layer, of the completion of data reception. Sun workstation 2-2 is responsible for receiving messages and registers. It reads status information and checks whether an error occurred during transmission and processes the received data. The data transfer between the layers is made through a first in first out (FIFO) register, and the communication path is established through a virtual path identifier (VPI) and a virtual channel identifier (VCI).

2 is a block diagram showing an interface device between an ALL layer and a higher layer in transmission according to the present invention, and is a register for storing control information. 10; The register by inputting a predetermined address (Add) and a bus control (AS) signal A decoding unit 20 for enabling 10; The register is generated by generating a predetermined address (Add) and a bus control (AS) signal. The control information is stored in (10), and an acknowledgment (ACK) signal is received and registered. This normally A line workstation 2 that recognizes that it has been set; And an acknowledgment signal generator 30 for delaying the output of the decoder 20 to generate an acknowledgment (ACK) signal so that the host computer which is the upper layer is a register of the ALL layer. Control information in And the acknowledgment (ACK) signal Check that it is loaded.

In addition, the decoding unit 20 includes an address decoder 20 for decoding an address and an oragate 24 for ORing an address strobe (AS) signal, and the acknowledgment signal generator 30 is the decoding unit. An orifice 32 and an oragate for ORing the first deflip-flop 31 delaying the output of the 20 and the output of the decoding unit 20 with the output of the first flip-flop 31 And a plurality of deflip-flops 33 and 34 for delaying the output of 32).

Next, the operation of the transmission interface apparatus according to the present invention configured as described above will be described.

When data is to be transmitted from the upper layer, the data to be transmitted is sent down to the AAL layer through a FIFO (not shown), and control information such as the length of the data to be transmitted is outputted with a predetermined address. Record in (10). In this way, the higher layer register An example of control information written in (10) is shown in Table 4 below.

As shown in Table 4 above, in the case of transmission according to the AAL3 / 4 protocol, the upper workstation 2 has 1 bit u control information, 1 bit m control information and 16 bits length through the input / output bus (SBUS). (LI) Register control information (10), the characteristics and length of the data to be transmitted to the AAL layer are informed, and in case of transmission according to the AAL5 protocol, the upper workstation 2 of the upper layer transmits one bit of OAM control information and Registers 1-bit m control information and 16-bit length (LI) control information It writes to (10) and informs the characteristic and length of data transmitted to AAL layer. Register The size of (10) can be implemented as 32 bits like the data size of the I / O bus so that the remaining bits can be used as a spare for later.

The address decoder 22 registers the line workstation 2 When a predetermined address (e.g., 0000077 _H ) is output to access 10, the output is low, and when the address strobe AS goes low, It is activated by applying a row to (10).

At this time, the acknowledgment signal generator 30 may compare the output of the first flip-flop 31 and the output of the decoder 20 with the output of the deflip-flop 31 to delay the output of the decoder 20. By the OR gate 32 and the de-flop flops 33 and 34 for delaying the output of the OR gate 32, an acknowledgment (ACK) signal is inputted in accordance with the timing of the line workstation (2). ), And outputs a data_arrive_indication signal to the AAL layer.

As described above, the register of the interface device implemented in hardware when the upper layer transmits to the AAL layer according to the present invention. Improve the interface speed by using, and improve the reliability by transmitting the general data and control information separately.

Claims (3)

In the ATM communication system layered into the physical layer, ATM layer, AAL layer, and upper layer, the transmission data is transmitted to the AAL layer through a first-in first-out buffer, and control information is transferred from the upper layer to the AAL layer using a separate register. In the asynchronous transfer mode communication device, a register for storing control information received from a higher layer 10; The register by inputting a predetermined address (Add) and a bus control (AS) signal A decoding unit 20 for enabling 10; The register is generated by generating a predetermined address (Add) and a bus control (AS) signal. The control information is stored in (10), and an acknowledgment (ACK) signal is received and registered. 10 normally A host computer 2 which recognizes that it is loaded; And an acknowledgment signal generator 30 for delaying the output of the decoder 20 to generate an acknowledgment (ACK) signal so that the host computer which is the upper layer is a register of the AAL layer. Control information in Through the acknowledgment signal The transmission interface device of the AAL layer, characterized in that it can be confirmed that the. The transmission interface apparatus of claim 1, wherein the decoding unit (20) comprises an address decoder (20) for decoding an address and an oragate (24) for logically combining an address strobe (AS) signal. . The method of claim 1, wherein the acknowledgment signal generator 30 is a first flip-flop 31 for delaying the output of the decoding unit 20 and the output of the decoding unit 20 to the flip-flop An AAL layer transmission interface device comprising an orifice (32) and a plurality of deflip-flops (33, 34) for delaying the output of the oracle (32).