KR0140679B1 - Circuit for processing sscop - Google Patents

Abstract

The present invention relates to a SSCOP processing circuit that implements SSCOP in the ATM communication method, and stores the state and state variables of the entire circuit, receives various signals from the upper layer or the received message, adjusts the state, and controls accordingly. A state controller 10 configured to output a signal and an error signal; A timer 20 configured to output predetermined time information according to the control signal of the state controller 10; The PDU transmitter which receives the data transmitted from the upper layer stored in the SSCOP FIFO 30 by the control signal of the state controller 10 and adds a pad and a control field of a predetermined length to the AAL FIFO 100 to output it. 40); A reception queue FIFO 50 that reads and stores a reception message stored in the reception AAL FIFO 102 and outputs the received message to the reception SSCOP FIFO 52; A PDU analysis unit 60 for interpreting a message input to the reception queue FIFO 50 and inputting a PDU type or various state variables to the state control unit 10; It is composed of a CPU 70 for initializing the entire circuit by the control signal of the state control unit 10.

Description

SSCOP (Service Specific Connection Oriented Protocol) Processing Circuit

1 is a diagram showing the structure of a signal protocol including a B-ISDN signal adaptation layer,

FIG. 2 is a diagram illustrating a PDU mapping structure of the signal adaptation layer shown in FIG. 1;

3 is a flowchart illustrating a signal link activation, deactivation and recovery of the signal adaptation layer;

4 is a block diagram showing an SSCOP processing circuit according to the present invention;

5 is a circuit diagram illustrating a processing circuit according to a length signal when transferring from an SSCOP to a transmission queue FIFO in the SSCOP processing circuit according to the present invention;

6 is a diagram illustrating a processing circuit according to a length signal when transmitting from a receiving AAL FIFO to a receiving queue FIFO in the SSCOP processing circuit according to the present invention.

* Explanation of symbols for main parts of the drawings

10: state control unit 12: state variable storage unit

14: error state storage unit 16: state processing unit

20: Timer 30: SSCOP FIFO

32: Transmission queue FIFO 34: Retransmission queue FIFO

36: Transmission buffer 40: PDU transmitter

50: Receive queue FIFO 52: Receive SSCOP FIFO

54: receiving queue buffer 60: PDU analysis unit

70: CPU100: AAL FIFO

102: Receive AAL FIFO

The present invention relates to a circuit for implementing the signal protocol used in the B-ISDN, which is based on the Asynchronous Transfer Mode (ATM) communication method, and particularly to the user, layer 3 of the signal adaptation layer (SAAL). The present invention relates to a circuit for implementing an SSCOP that receives a signal data transmission request from a network and transmits the same to the peer layer without error.

Recently, as the means of communication is rapidly digitized and the development of optical communication enables wide band transmission, broadband ISDN (Broadband Integrated Services Digital Network) has emerged as a next-generation communication network to meet various user needs. In this B-ISDN, not only existing narrowband services such as telemetering, data terminal, telephone, and facsimile, but also broadband services such as video telephony, video conferencing, high-speed data transmission, and video signal transmission are provided in the frequency band and speed. It is implemented based on ATM communication method which is an asynchronous delivery mode to accommodate all.

Here, the ATM communication method is a method of communicating by asynchronous time division multiplexing (ATDM) of a total of 53 bytes of ATM cells composed of a 5-byte header section and a 48-byte user information section by cell unit. It is similar to the conventional packet communication method in that it transmits, but ATM communication method handles signals of real time and identity rate, and is different in that it can be used not only in local area network but also huge public network.

In the ATM communication method, the signal protocol structure is shown in FIG. 1. The functions of each of these layers are shown in Table 1.

As shown in Table 1, the structure of the ATM protocol is divided into vertical structures such as a physical layer, an ATM layer, a signaling adaptation layer (SAAL), and a higher protocol layer. Is divided into a common part layer (CP ALL; Common Part AAL) and a service specific convergence sublayer (SSCS). In addition, the service specific sublayer includes an SSCF (Service Specific Co-ordination Function) and an SSCOP (Service). Specific Connection Oriented Protocol).

On the other hand, each of these layers has a mapping structure as shown in FIG. 2. SSCF adds 5 octets of information to the data received from the upper layer and transfers it to the SSCOP layer, and an integer of 4 octets in the SSCOP layer. The PAD and the predetermined trailer information are added to the CPCS layer to be arranged by ship, and the CPCS layer is added to the SAR layer by adding the PAD and the predetermined trailer to be an integer multiple of 48 octets.

The SAR sublayer informs the end of the SAR-PDU to enable the preservation of the SAR-PDU, to process congestion information, and to process loss priority information, and to separate the data received from the CPCS into 48 octets. The ATM layer transmits the data to the ATM layer by adding a predetermined header of 5 bits to the transmitted data.

SSCOP performs specific functions of signal adaptation layer and is used to transfer service data units (SDUs) of variable length between users and has the function of recovering lost or damaged SDUs. Receives the signal data transmission request from the user or layer 3 of the signal adaptation layer and transmits it to the same layer transparently without error. This corresponds to the existing layer 2 and is the user network interface (UNI) and the network node interface. Commonly used for (NNI; Network Node Interface), and its functions are shown in Table 2 below.

In the SSCOP sublayer, which performs the function as shown in Table 2, the signal flow of the signal adaptation layer shown in FIG. When the request for deactivation and recovery is delivered to the SSCF layer, the SSCF layer sends predetermined primitives to the SSCOP, and the SSCOP creates a message corresponding to the primitive and delivers the message to the CPCS layer, such as CPCS_UNITDATA_invoke and CPCS_UNIT_signal. Two signals are to be used.

At this time, the message transmitted from the SSCOP sublayer, that is, the SSCOP PDU has a structure in which 4 octets of control fields are added to the data transmitted from the SSCF as shown in FIG. 2, and the maximum possible length is the maximum of the CPCS PDU. Since the possible length is 65528 octets minus 8 octets of the CPCS trailer, the remaining 65524 octets minus the 4 octets control field is the maximum possible length of SSCOP_UU.

The 4 octet control field is composed of a 2-bit pad length, a 2-bit unused portion, a 4-bit PDU type, and a 3-octet length PDU variable.

Accordingly, the present invention transmits a predetermined message to the AAL layer or receives the data delivered from the SSCF sublayer through the AAL layer so as to receive a request for transmission of signal data from the SSCF sublayer and transparently transmits the same to the peer layer without errors. Its purpose is to provide an SSCOP processing circuit intended for delivery to a layer.

It is another object of the present invention to provide an SSCOP processing circuit which simply implements a function of retransmitting an unsent message.

The circuit of the present invention for achieving the above object, stores the state and state variables of the entire circuit, and receives various signals from the upper layer or received message to adjust the state and accordingly various control signals and error signals An output state control unit; The timer is configured to output predetermined time information by the control signal of the state controller, and the pad and control field of a predetermined length are added by receiving data transmitted from an upper layer stored in the SSCOP FIFO by the control signal of the state controller. A PDU transmitter configured to output the AAL FIFO; A reception queue FIFO configured to read and store a reception message stored in the reception AAL FIFO and output the received message to the reception SSCOP FIFO; A PDU analysis unit for interpreting a message input to the reception queue FIFO and inputting a PDU type or various state variables to the state control unit; The CPU is configured to initialize the entire circuit by the control signal of the state controller.

In addition, the configuration of the present invention for achieving the above another object is, the transmission queue FIFO and the data stored in the transmission queue FIFO to be stored by adding a predetermined length information to the data stored in the SSCOP FIFO a predetermined sequence number A retransmission means composed of a transmission buffer managed only by the transmission data and outputted only through the retransmission queue FIFO to the PDU transmitter; The reception queue buffer is configured to add length information to the reception message stored in the reception queue FIFO, and to compensate for the missing message and output the received message to the reception SSCOP FIFO.

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

4 is a diagram illustrating an SSCOP processing circuit according to the present invention, which stores state and state variables of an entire circuit, receives various signals from an upper layer or a received message, adjusts the state thereof, and controls various control and error signals accordingly. State control unit 10 to output the; A timer 20 configured to output predetermined time information according to the control signal of the state controller 10; The PDU transmitter which receives the data transmitted from the upper layer stored in the SSCOP FIFO 30 by the control signal of the state controller 10 and adds a pad and a control field of a predetermined length to the AAL FIFO 100 and outputs it to the AAL FIFO 100. PDU analysis unit 60 and input to 10); It is composed of a CPU 70 for initializing the entire circuit by the control signal of the state control unit 10.

Here, the state control unit 10 includes a state variable storage unit 12 storing various state variables, an error state storage unit 14 storing an error situation, and a signal input from an upper layer and a lower layer. It consists of a state processing unit 16 to adjust the state of the entire circuit by the signal obtained from the message (PDU) delivered from.

The state variable storage unit 12 is a register for storing state variables of the SSCOP, and the state variables of each SSCOP are as shown in Table 3 below.

The error state storage unit 14 is a part for storing various errors occurring during communication, and is composed of a register for storing an error state of 1 byte and an error number of 1 byte.

In addition, the timer 20 is configured to be controlled by the control of the state control unit 10 is composed of all four.

In addition, the transmission queue FIFO 32, which adds and stores length information to the data stored in the SSCOP FIFO 30, and manages data stored in the transmission queue FIFO 32 by a predetermined sequence number, is lost during transmission. Retransmission means composed of a transmission buffer 36 capable of retransmitting and outputting only the data to the PDU transmitter 40 through a retransmission queue FIFO 34; The reception queue buffer 54 is configured to add length information to the reception message stored in the reception queue FIFO 50 and to compensate for the missing message and output the received message to the reception SSCOP FIFO 52.

At this time, in storing the data of the SSCOP FIFO (30) in the transmission queue FIFO (32), it is preferable to store two words each indicating the length information of the message in front of the data, the length information to be stored at this time The actual length of the data and the length of the data in different circuits are stored by storing the actual length information of the message for each word and the length information in octets, including the pad added to align the integer number of four octets of the message, respectively. It can be easily used to grasp information.

As such, an embodiment of a circuit for calculating length information from a message to add predetermined length information to the message is illustrated in FIG. 5, and includes a signal including length information of a message transmitted from an upper layer. To the divider 74 and the divider 74 which output the quotient and the remainder which are the result of dividing the actual length information of the message output from this register 72 by 4 with the register 72 to be stored. The actual length information of the message output from the register 72 by the operation of the adder 76 and the down counter 78 which adds 1 to the quotient of the divider and outputs the result of the remainder. And a multiplexer 80 which sequentially outputs length information of the message output from the adder 76 to the transmission queue FIFO 32.

Therefore, the transmission queue buffer 32 stores the information corresponding to the actual length in front of the message and the length information in octets for sorting in multiples of 4 together with the message, thereby more smoothly processing the transmitted message. It becomes possible.

In this way, a retransmission means for storing a message including predetermined length information is provided, so that the PDU transmitter 40 can additionally transmit a lost message through the SD-PDU.

Here, the PDU transmitter 40 is responsible for the transmission of various PDUs, and serves to generate and transmit each message by receiving the signal from the state control unit 10, and the data of the normal upper layer is SSCOP FIFO. When inputted from 30 and retransmitted, it is inputted from the retransmission queue FIFO 34, and the PDU change is mapped to the state variables stored in the state variable storage unit 12.

Meanwhile, the reception queue FIFO 50 reads a message received from the reception AAL FIFO 102, which is a lower layer.

At this time, the PDU analysis unit 60 analyzes the message input to the reception queue FIFO 50 to determine the message type, and analyzes the variable and delivers it to the state control unit 10.

In this case, in order to fit the format of the message used in the SSCOP layer, it is preferable to extract and store the length information of the received message. FIG. 6 illustrates an embodiment of a circuit for extracting the length information of the received message.

That is, the divider 82 which outputs the quotient and the remainder by dividing the actual length signal of the message transmitted from the received AAL FIFO 102 of the lower layer by 4, and the remainder value from the divider 82 The divider 82 is operated by the operation of the subtractor 84 and the down counter 88, which inputs and outputs the length information of the message by subtracting the inserted pad length from the length signal of the message. The multiplexer 86 outputs the length information according to the quotient of 4 divided by the actual length information of the message output from and the length information of the message output from the subtractor 84 to the receiving queue FIFO 32. Consists of

Accordingly, by storing the message transmitted from the lower layer and the length information of the message obtained in the circuit, it is possible to easily process the message in another circuit.

As described above, the SSCOP processing circuit embodying the present invention is equipped with a separate storage means for retransmission to correspond to an optional retransmission protocol, and has a function of retransmitting untransmitted PDUs, thereby providing a conventional GO BACK N protocol. There are many differences.

In addition, in the present invention, although the transmission is made without receiving approval for each PDU, this is possible because the transmission using a communication medium with a low error rate of optical communication.

Claims (2)

A state controller 10 for storing the state and state variables of the entire circuit, receiving various signals from a higher layer or a received message, adjusting the state, and outputting various control signals and error signals accordingly; A timer 20 configured to output predetermined time information according to the control signal of the state controller 10; The PDU transmitter which receives the data transmitted from the upper layer stored in the SSCOP FIFO 30 by the control signal of the state controller 10 and adds a pad and a control field of a predetermined length to the AAL FIFO 100 for outputting. 40); A reception queue FIFO 50 for reading and storing a reception message stored in the reception AAL FIFO 102 and outputting the received message to the reception SSCOP FIFO 52; A PDU analysis unit 60 for analyzing a message input to the reception queue FIFO 50; SSCOP processing circuit comprising a CPU (70) for initializing the entire circuit by the control signal of the state control unit (10). The transmission queue FIFO 32, which stores length information added to data stored in the SSCOP FIFO 30, and manages data stored in the transmission queue FIFO 32 by a predetermined sequence number. A retransmission means composed of a transmission buffer 36 capable of retransmitting only data lost during transmission to the PDU transmitter 40 through a retransmission queue FIFO 34; The reception queue buffer 54 is configured to add length information to the reception message stored in the reception queue FIFO 50 and to compensate for the missing message and output the received message to the reception SSCO FIFO 52. SSCOP processing circuit.