KR100212832B1 - Utopia receiving connection apparatus of atm adaptor - Google Patents

Abstract

The present invention relates to an apparatus for connecting a SAR layer and a physical layer of an ATM adapter in a UTOPIA method, and receives a data buffer of a byte unit from the physical layer chip according to a data strobe (/ DSTRV) signal and temporarily stores the received data buffer. 51; A reception rate matching buffer 52 which receives the reception data from the reception data buffer and outputs data in units of bytes by a read buffer (/ rd_fifo) signal and displays the state of the buffer by an empty flag; A CRC processing unit (53) which receives the output of the reception rate matching buffer and performs a CRC operation on a header of an ATM cell to check for a CRC error and to output received data; An event counter 54 which counts a predetermined number repeatedly in synchronization with the reception clock RxClk; And a read buffer (/ rd_fifo) signal for reading data from the reception rate matching buffer 52 by receiving the output of the event counter, a receive enable signal (/ RxEnb), and a CRC error signal, and notifying the start of a receiving cell. RxSOC signal, and control signal generator 55 for generating a receive buffer beam (/ RxEmpty) signal to inform that there is no received data, the circuit design is simple and the operation is stable. .

Description

UTOPIA receiving access device of ATM adapter

1 is a block diagram showing the configuration of a typical ATM adapter.

2 is a block diagram showing a UTOPIA connection apparatus for connecting the physical layer of the SAR layer by applying the present invention.

3 is a block diagram showing a UTOPIA receiving access device according to the present invention;

* Explanation of symbols for main parts of the drawings

3: ATM adapter 32: SAR chip

33: physical layer chip 33-1: physical layer transmission chip

33-2: Physical layer receiving chip 40: UTOPIA connection device

51: Receive rate matching buffer 52: Receive data buffer

53: CRC processing unit 54: event counter

55: control signal generator

The present invention relates to an ATM connection device for connecting a terminal device such as a computer system to an ATM network (ATM LAN or ATM WAN), and more specifically, a segmentation and reassembly (SAR) layer and a physical layer. The present invention relates to a UTOPIA access device for accessing a SAR layer to a physical layer that does not support UTOPIA access in an ATM access device classified as.

In general, ATM technology is a communication technology for dividing a message having an arbitrary size into a plurality of ATM cells having a size of 53 bytes, and then transmitting it through a transmission medium. In particular, it is widely regarded as the next generation communication technology to replace the FDDI (Fiber Distributed Data Interface) in the computer network field.

When configuring a network (ATM LAN or ATM WAN) using such ATM technology, an ATM access device (called an ATM adapter or ATM card) is required to connect a host system (or terminal) to an ATM network. In addition, this ATM interface divides an arbitrary message to be transmitted by the host system according to predetermined AAL protocols (AAL1, AAL2, AAL3 / 4, AAL5) to form an ATM cell, or reassembles a received ATM cell to form a message. It is divided into a reconstruction SAR (Segementation And Reassemble) layer and a physical layer that encodes an ATM cell received from the SAR layer and transmits it through a transmission medium or decodes an ATM cell received from the transmission medium and delivers it to the SAR layer.

In this case, in order to give flexibility to use ATM access devices (hereinafter referred to as ATM adapters) for various transmission media, a standard connection protocol is defined between the SAR layer and the physical layer, even if the physical layer is implemented in various forms. According to the report, the SAR layer provides easy access.

The Universal Test Operations PHY Interface for ATM (UTOPIA) is a standard interface method established by the 'ATM Forum' formed by companies and research institutes for early use of ATM technology to connect the SAR layer and the physical layer. .

However, the functions of the SAR layer necessary to implement the ATM adapter are already manufactured and marketed as integrated circuits (hereinafter referred to as SAR chips), and various integrated circuits for the physical layers (hereinafter referred to as physical layer chips) are also available. It is already widely used.

As a result, companies that manufacture integrated circuits offer ATM-related chipsets of various shapes and functions. Some physical layer chips, such as AMD's TAXI chips, do not have UTOPIA connectivity.

That is, SAR layer chips based on ATM technology can be UTOPIA-connected, but general-purpose physical layer chips, which have been widely used before the UTOPIA connection standard was completed, are not provided with UTOPIA connection, and therefore, TAXI chips to SAR layer chips are not provided. A separate UTOPIA connection device is required to connect chips such as the chip.

Accordingly, an object of the present invention is to provide a UTOPIA reception access apparatus of an ATM adapter for interfacing a chip of a physical layer without a UTOPIA connection function to a SAR layer.

In order to achieve the above object, the apparatus of the present invention connects a physical layer chip without a UTOPIA connection function to the split and assembly (SAR) chip in an ATM adapter implemented by being separated into a SAR needle and a physical layer chip. UTOPIA is equipped with a UTOPIA transmission connection device from the split and assembly chip to a physical layer chip and a UTOPIA reception connection device from a physical layer chip to a split and assembly chip. ) Receiving connection device,

A reception data buffer for receiving data in units of bytes from the physical layer chip according to a data strobe (/ DSTRV) signal and temporarily storing data; A reception speed matching buffer which receives the reception data from the reception data buffer and outputs data in byte units by a read buffer (/ rd_fifo) signal and displays the state of the buffer by an empty flag; A CRC processing unit which receives the output of the reception rate matching buffer and performs CRC operation on a header of an ATM cell to check whether there is a CRC error and to output received data; An event counter which simultaneously counts a predetermined number in parallel with the reception clock; And a read buffer (/ rd_fifo) signal for reading data from a receive rate matching buffer by receiving the output of the event counter, a receive enable signal (/ RxEnb), and a CRC error signal, and a start of a receiving cell indicating the start of a receiving cell. (RxSOC) signal, and a control signal generator for generating a reception buffer beam (/ RxEmpty) signal for indicating that there is no received data.

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

A typical ATM adapter to which the present invention can be applied includes a host system 1, as shown in FIG. A bus interface unit 31 for connecting with the host system; A SAR layer processing unit 32; It consists of a physical layer processing part 33, and the physical layer processing part 33 is comprised by the physical layer connection part 34 and the transceiver 35. Here, the SAR layer processor 32 may be implemented by one SAR chip, and the physical layer processor 33 may also be implemented by one physical layer chip.

The host system 1 is a computer or image processing system for transmitting any message or packet, such as image data or DBASE data, over a network, for example, a workstation.

The bus interface unit 31 is for interfacing the host system and the ATM adapter 3 through the I / O bus 2. The I / O bus is widely used as an industrial standard such as SBus, PCI, EISA, etc. In this case, SBus is generally used.

In this case, a method of connecting the ATM adapter 3 to the host system may include a program I / O, a bus master, a shared memory, and the like. In short, it is shown in Table 1 below.

In FIG. 1, the SAR layer processing unit 32 segments a message or packet of a host system input through the bus interface unit 31 into 53-byte ATM cells, and is received from the physical layer processing unit 33. The ATM cell is analyzed to see if an error has occurred, and then reassembled to recover a message or packet, and then transferred to a higher layer through the bus interface 31.

The physical layer connection unit 34 of the physical layer processing unit receives ATM cells input in parallel, performs scrambling and line coding, converts them in series, or decodes the serially received bit stream. Descramble and convert in parallel. Transmitting and receiving unit 35 of the physical layer processing unit converts a series of bit input serially into an optical signal and transmits it to an optical cable or modulates it into an electrical signal suitable for a transmission medium and transmits it through a coaxial cable, and transmits the optical signal received from the optical cable. The signal is converted into an electrical signal and output as a bit string, or the electrical signal received through a coaxial cable is demodulated and output as a bit string.

In the ATM adapter configured as described above, it is recommended to connect the SAR processing unit and the physical layer processing unit in a UTOPIA method. As described above, the UTOPIA connection method is a standard connection method between the physical layer and the SAR layer proposed by the ATM Forum. When transmitting from the SAR layer to the physical layer, the connection signal is TxData [7: 0], TxSOC, / TxEnb, / There are TxFull and TxClk, and the connection signal upon reception from the physical layer to the SAR layer includes RxData [7: 0], RxSOC, / RxEnb, / RxEmpty, and the like.

Here, TxData [7: 0] is ATM cell data (hereinafter, referred to as ATM transmission cell data, referred to simply as transmission data) transmitted from the SAR layer to the physical layer, and in TxSOC, the SAR layer is the ATM in the physical layer. Signal to indicate start of cell (SOC) (hereinafter referred to as transmission cell start signal). If this signal is 'high', byte data input as transmission data (TxData [7: 0]) Indicates that is the first byte of an ATM cell. / TxEnb is used to inform the SAR layer that the data transmitted as the transmission data (TxData [7: 0]) is valid cell data to the physical layer, and is a valid cell for the transmission data (TxData [7: 0]). It remains 'low' while there is data, and / TxFull is a signal to inform the physical layer that the transmission data is full and the data can't be accepted anymore (hereinafter referred to as a transmission full signal). Activated when low. TxClk represents the transmit clock.

In addition, RxData [7: 0] is ATM cell data (hereinafter, referred to as ATM receiving cell data, referred to simply as receiving data) transmitted from the physical layer to the SAR layer, and in RxSOC, the physical layer is an ATM cell in the SAR layer. Signal to indicate start of cell (SOC) (hereinafter referred to as reception cell start signal). If this signal is 'high', byte data outputted as received data RxData [7: 0] is Indicates that this is the first byte of an ATM cell. / RxEnb is to inform the SAR layer that the data transmitted as the received data (RxData [7: 0]) is valid cell data. The valid cell is used for the received data (RxData [7: 0]). It remains 'low' while there is data, and / RxEmpty is a signal (hereinafter referred to as receive buffer beacon) to inform the physical layer that the received data is empty and there is no more data to transmit to the SAR layer. Activated when low.

On the other hand, according to the present invention, the UTOPIA connection device 40 for connecting a TAXI chip without UTOPIA connection function to the SAR layer is composed of a transmission connection part 42: a reception connection part 44, as shown in FIG. The UTOPIA connection device 40 is located between the chip 32 of the SAR layer and the chip 33 of the physical layer to connect them.

Here, transmission data (TxData [7: 0]), transmission cell start (TxSOC), transmission full (/ TxEnb), and transmission clock (TxClk) signals are input from the SAR chip 32 to the transmission connection section 42. The transmission full (/ TxFull) signal is input from the connection portion 42 to the SAR chip 32. Receive data (RxData [7: 0]), receive cell start (RxSOC), receive buffer beam (/ RxEmpty) signals are input from the receive connection section 44 to the SAR chip 32, and are received from the SAR chip 32. A receiver enable (/ RxEnb) signal is input to the connection unit 44.

Then, DI [7: 0] for transmitting the transmission data in byte units and a strobe (STRB) signal for latching the transmission data are input from the transmission connection section 42 to the physical layer transmission chip 33-1. The D [7: 0] and data strobe (DSTRV) signals are input from the physical layer receiving chip 33-2 to the receiving connection unit 44. At this time, the ACK signal is input from the physical layer transmission chip 33-1 to the transmission connection unit 42 to transfer data asynchronously by the strobe signal and the ACK signal. The DSTRB is a signal for the physical layer receiving chip 33-2 to transmit the received data to the receiving connection unit 44.

Therefore, the connection between the SAR chip 32 and the UTOPIA connection device 40 is made by the UTOPIA method, and the connection between the UTOPIA connection device 40 and the physical layer chip 33 is appropriately made in accordance with the characteristics of the physical layer chip.

On the other hand, the UTOPIA reception connection apparatus according to the present invention, as shown in Figure 3, the reception data buffer 51, the reception speed matching buffer 52, CRC processing unit 53, event counter 54, and the control signal It is composed of a generation unit 55 and CRC check the byte data received from the physical layer receiving chip (33-2) and transfers to the SAR layer chip (32).

Here, the reception data buffer 33-2 latches the data Din_RxTAXI [7..0] of the byte unit received from the physical layer receiving chip according to the data strobe DSTRV and then latches the data Din_RxTAXI [7 ..]. 0] is stored in the reception rate matching buffer 52 in accordance with the write buffer signal / wr_RxBuf, although there is a slight difference in the connection method according to the characteristics of the physical layer reception book, as in the embodiment of the present invention. Am7969, a TAXI receiving chip, can be connected with only the data line (Din_RxTAXI [7..0]) and data strobe (DSTRV) in units of bytes.

The reception rate matching buffer 44 is implemented as a FIFO (First_In_First_Out) and sequentially outputs data (Din_RxBuf [7..0]) input from the reception data buffer 51 according to the read buffer (/ rd_fifo) signal and buffers. The empty signal is notified to the control signal generator 55 through the empty_flag, and if there is data received, the empty flag is 'high' and if no data is received, the empty flag is 'low'. 'to be.

If there is received data, the CRC processing unit 53 receives data from the reception rate matching buffer 52 according to the control signal, performs a CRC operation on the 4-byte header of the ATM cell, and then receives the fifth result. If an error has occurred in comparison with the HEC byte, the CRC error detection signal Err_CRC is output to the control signal issuing unit 55, and the received data is discarded. If there is no error, 53 bytes of ATM cell data including 5 bytes of hair. Is transmitted over the data bus RxData [7..0] to the SAR layer.

The event counter 54 generates an event signal by counting a predetermined number of clocks (Inclk) in which the reception clock (/ RxClk) inputted from the SAR layer is inverted, and operates as a modulo 55 in an embodiment of the present invention. In synchronization with the reception clock, counting is repeated from 0 to 55. At this time, if the SAR layer cannot be received (ie, when RxEnb is high) under the control of the control signal generator 55, the counting operation is suspended.

The control signal generator 55 checks the empty_flag of the reception rate matching butter 52 whenever the count value of the event counter 4 is 0, and if there is data to be received (that is, empty). If the flag is 'high', read buffer (/ rd_fifo) signal is generated to read data in byte unit and output to SAR layer after CRC check. At this time, the RxSOC signal is transmitted to the SAR layer to indicate the first byte of the valid cell. If there is no data received (ie, if the empty flag is 'low'), the reception butter beam (/ RxEmpty) is transmitted. A low signal indicates that no data has been received at the SAR layer. If the SAR layer is in an unreceivable state), the counter operation of the event counter 54 is suspended.

As such, the control signal generator 56 checks the empty flag when the counter value is 0 in the 55 event counter 55. When the empty flag is 'high', the 53-byte data is checked. Generates a signal for reading the signal, a signal for controlling the CRC operation, and a reception cell start (Rx_SOC) signal. If the empty flag is 'low' as a result of the irradiation, a reception buffer beam (/ RxEmpty) signal is generated.

As described above, the UTOPIA connection apparatus according to the present invention provides the UTOPIA type connection to the SAR layer, and provides the UTOPIA type connection function by providing signals and data according to the characteristics of the physical layer chip. Allows the chips in the physical layer to connect to the SAR layer.

Furthermore, the UTOPIA receiving access device according to the present invention has a receiving rate matching buffer to alleviate the difference in transmission speed between the SAR chip and the physical layer chip, and to simplify the circuit design and stabilize the operation by using an event counter. have.

Claims (1)

The splitting and assembly (SAR) is used to connect a physical layer device without a UTOPIA connection function to the splitting and assembly (SAR) device in an ATM adapter which is divided into a split and assembly (SAR) device and a physical layer device. In the UTOPIA connection apparatus provided with a UTOPIA transmission connection device from a device to a physical layer device and a UTOPIA reception connection device from a physical layer device to a division and assembly (SAR) device, the utopia (UTOPIA) connection device is provided. UTOPIA) a reception data buffer 51 for receiving and temporarily storing data in byte units from the physical layer device according to a data strobe (/ DSTRV) signal; A reception speed matching buffer 52 which receives the reception data from the reception data buffer and outputs data in units of bytes by a read buffer (/ rd_fifo) signal and displays the state of the buffer by an empty flag; A CRC processing unit (53) which receives the output of the reception rate matching buffer and performs CRC operation on the header of the ATM cell to check for CRC error and to output received data; An event counter 54 which repeatedly counts a predetermined number in synchronization with reception RxClk; And a read buffer (/ rd_fifo) signal for reading data from the reception rate matching buffer 52 by receiving the output of the event counter, a receive enable signal (/ RxEnb), and a CRC error signal, and notifying the start of a receiving cell. 8. A UTPIA reception access apparatus of an ATM adapter having an RxSOC signal and a control signal generator 55 for generating a reception buffer beam (/ RxEmpty) signal for indicating that there is no reception data.