KR20000032331A - Device for automatic insertion of frame check sequence and method therefor - Google Patents

Abstract

PURPOSE: A device for automatic insertion of a frame check sequence and a method for the same are provided to save time consumed for calculation of CRC to be performed by a switching section as well as to reduce time required for transmission of the data by the switching section by allowing an automatic insertion of the frame check sequence. CONSTITUTION: A device for automatic insertion of a frame check sequence according to the present invention comprises a first-in first-out of media access control (MAC) transmission section (41) for temporarily storing data inputted from the switching section, a preamble and jam generation section (43) for generating a preamble that alarms a start of a packet or data to be jammed in a network, a back-off and internal gap timer (42) for measuring time to re-transmit the data in case of being jammed in the network or the time to be taken for transmitting another packet after transmission of a first packet, CRC generation sections (45, 62) for generating information of errors pertaining to the data to be transmitted, a transmission section (40) consisting of a first multiplexer (44) for selecting and outputting either one of the data inputted from the preamble and jam generation section (43) or from the first-in first-out section (41) of MAC transmission, a second multiplexer (51) for selecting and outputting either one of the data looped back from the first multiplexer (44) of the transmission section (40) or from the network. a first-in first-out of MAC receiving section for temporarily storing data inputted from the second multiplexer (51), an address CAM for determining a recipient of the received data and whether or not the received data are a receivable packet, and a receiving section (50) consisting of a CRC and a CAM filter for detecting an error of the received data and ignoring the data failing to pass a filter.

Description

Frame inspection sequence automatic insertion device and method

The present invention relates to an apparatus and method for automatically inserting a frame check sequence, and more particularly, to a device for transmitting a local area network (LAN) using Ethernet, which is automatically referred to as a frame check sequence (hereinafter referred to as "FCS"). The present invention relates to an apparatus and method for automatically inserting a frame check sequence to reduce unnecessary data transfer operation and to suppress time required for FCS calculation.

1 is a block diagram showing a configuration of a transmission apparatus of a local area network (LAN) using Ethernet, and a plurality of Ethernet media access control apparatuses operating according to a protocol that satisfies the IEEE 802.3 specification as shown in FIG. (Hereinafter referred to as "Ethernet MAC") 20a to 20n; A switching unit (10) for sending data received through the Ethernet MAC (20a to 20n) to a designated Ethernet MAC or for arbitrarily generating data to a desired Ethernet MAC or another system; It consists of a network 30 which is a medium for transmitting data through a cable defined in the IEEE 802.3 specification, the Ethernet MAC (20a to 20n) is a MAC transmission for temporarily storing a packet for transmission as shown in FIG. First-in, first-out unit 41, a preamble or a preamble for notifying the start of the packet (preamble) or a preamble and jam generating unit 43 for generating data for the collision (jamming) in the data collision in the network, and data collision in the network Backoff and internal gap timers 42, which measure the time for retransmission if they occur, or the time from one packet transmission to the next in the network, and errors regarding the data being transmitted A circulation margin test (hereinafter referred to as "CRC") generation unit 45 for generating information; A transmitter 40 including a first multiplexer 44 for selecting and outputting one of data input from the preamble and jam generator 42, the CRC generator 45, and the MAC first-in first-out unit 41; ; From the second multiplexer 51 for selecting and outputting one of the data (loop back) input from the first multiplexer 44 of the transmitter 40 or the data input from the network, and from the second multiplexer 51 MAC reception first-in-first-out unit 52 for temporarily storing the input data, the address CAM 53 for determining who the destination of the received data is or whether the packet should not be received, and whether there is an error in the received data. After the test, it is composed of a receiver 50 composed of a CRC and CAM filter 54 passing through the filter and ignoring data having errors or not passing through the filter.

The operation of the conventional device configured as described above will be described with reference to FIGS. 3 and 4.

First, when data starts to be received from the network, the receiver 50 starts to store the received data in the MAC first-in first-out 52, and performs CRC using the stored data, and then transmits the data to the switching unit 10. In this case, the FCS of data may or may not be transmitted as necessary by the switching unit 10. At this time, the address CAM 53 determines who is the destination of the received data or a packet that should not be received, and outputs the corresponding signal to the CRC and CAM filter 54, and receives the received CRC and CAM filter 54. After checking whether there is an error in the received data, it passes the filter to ignore data that has an error or failed to pass.

The switching unit 10 analyzes the data transmitted from the receiving unit 50 to determine and transmit the MAC port to which the data should be transmitted, and generates data other than the data received from the receiving unit 50 as necessary. Can also be sent.

In addition, when data is transmitted from the switching unit 10, the transmission unit 40 stores the data in the MAC transmission first-in first-out 41, at which time the back off and internal gap timer 42 as shown in FIG. After the two packets are transmitted, the time until the next packet is transmitted is measured. When the measured time reaches the set time, as shown in FIG. 4, a preamble indicating the start of the packet is transmitted, and at the same time, the CRC is transmitted. Start the calculation.

After the transmission is completed, the destination address, source address, shape size, and data are sequentially transmitted, and it is determined whether the CRC is set to be transmitted. If not, the next time after the CRC is transmitted, The time until the packet is transmitted is measured.

As described above, in the related art, a pin is placed between the switching unit and the transmission unit to indicate whether to include the CRC in order to determine whether to include the CRC in the data transmitted from the switching unit to the transmission unit. The problem of using additional pins;

In order to solve the problem, the switching unit calculates the CRC and sends the data without using a pin. When the transmitter does not calculate the CRC, it takes a long time to calculate the CRC at the switching unit. There was a delay.

Accordingly, the present invention has been devised to solve the above-mentioned conventional problems, and automatically inserts a frame check sequence (hereinafter referred to as "FCS"), thereby reducing unnecessary data transmission operations, and FCS. It is an object of the present invention to provide an apparatus and method for automatically inserting a frame check sequence to suppress a time required for calculation.

1 is a block diagram showing a configuration of a transmission apparatus of a local area network (LAN) using a conventional Ethernet.

2 is a block diagram showing the configuration of the Ethernet MAC in FIG.

3 is an exemplary view showing a conventional Ethernet frame format.

4 is a flowchart illustrating the operation during transmission of FIG. 2.

Figure 5 is a block diagram showing the configuration of one embodiment of the frame inspection sequence automatic insertion apparatus of the present invention.

FIG. 6 is a flowchart illustrating an operation during transmission of FIG. 5.

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

10: switching unit 30: network

40, 60: transmission unit 41: MAC transmission first-in first-out

42: back off and internal gap timer 43: preamble and jam generating unit

44, 63: first multiplexer 45, 62: CRC generation unit

50: receiver 61: comparator

In order to achieve the above object, the structure of the apparatus for automatically inserting a frame check sequence according to the present invention is a MAC first-in first-out unit that temporarily stores data input from a switching unit, and a preamble or network that notifies the start of a packet. The preamble and jam generator which generates data for jamming in case of data collision, and the time for retransmitting when data collision occurs in the network, or the next packet is transmitted after one packet is transmitted in the network. A backoff and internal gap timer for measuring the time until transmission, and a cyclic margin check (hereinafter referred to as " CRC ") generation unit for generating error information about data to be transmitted; A transmitter comprising a first multiplexer for selecting and outputting one of data input from the preamble and jam generator, a CRC generator, and a MAC first-in first-out unit; A second multiplexer for selecting and outputting one of data input from a first multiplexer of the transmitter or data input from a network; and a MAC reception first-in, first-out unit configured to temporarily store data input from the second multiplexer. After checking whether there is an error in the address CAM to determine who is the destination of the received data or the packet that should not be received, and if there is an error in the received data, the data is passed through the filter to check whether there is an error or failed to pass the filter. An apparatus for inserting a frame check sequence including a receiver configured to ignore CRC and CAM filters, the apparatus comprising: a comparison unit for comparing a predetermined byte of data input from the switching unit with a calculated CRC value and determining whether to attach the CRC accordingly; Characterized in that configured.

In addition, the method includes: a first step of measuring a time from one packet transmission to the next packet transmission, and then determining whether the measured time reaches a set time; A second step of transmitting a preamble indicating the start of a packet when the determination result of the first step is reached, and simultaneously transmitting a destination address, a source address, a shape size, and data after starting a CRC calculation; A third step of determining whether a predetermined byte of data to be transmitted is equal to a calculated CRC value when the execution of the second step ends; If the determination result of the third step is different, the CRC is transmitted. If not, the fourth step of returning to the first step is performed.

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

FIG. 5 is a block diagram illustrating an embodiment of an apparatus for automatically inserting a frame inspection sequence according to the present invention. As shown in FIG. 5, a MAC transmission first-in first-out unit for temporarily storing data (packets) transmitted from the switching unit 10 is illustrated in FIG. 41), a preamble and jam generating unit 43 for generating data for jamming when a data collision occurs in a preamble or network for notifying the start of a packet, and again when a data collision occurs in the network. A backoff and inner gap timer 42 for measuring the time for retransmission or for the time from one packet transmission to the next packet transmission in the network, and generating error information about the data being transmitted. The cyclic margin test (hereinafter, referred to as "CRC") value is compared with the calculated portion of the CRC by the generation unit 62 and the predetermined byte of data input from the switching unit 10, and accordingly A first unit for selecting and outputting one of data inputted from a comparator 61 for determining whether to attach or not, and data input from the preamble and jam generator 42, the comparator 61, and the MAC transmission first-in first-out unit 41; A transmission unit 60 composed of a multiplexer 63; From the second multiplexer 51 to select and output one of the data (loop back) input from the first multiplexer 44 of the transmitter 60 or the data input from the network, and from the second multiplexer 51 MAC reception first-in-first-out unit 52 for temporarily storing the input data, the address CAM 53 for determining who the destination of the received data is or whether the packet should not be received, and whether there is an error in the received data. After the test, the filter is configured with a receiver 50 composed of a CRC and a CAM filter 54 passing through the filter and ignoring data having errors or not passing through the filter.

Referring to Figure 6 attached to the operation of the embodiment according to the present invention configured as described above are as follows.

The reception operation in the present invention is the same as the conventional operation described above, and a description thereof will be omitted.

When data is transmitted from the switching unit 10, the transmission unit 40 stores the data in the MAC first-in first-out 41, at which time the backoff and internal gap timer 42 is one packet as shown in FIG. After the transmission, the time until the next packet is transmitted is measured. When the measured time reaches the set time, as shown in FIG. 4, a preamble indicating the start of the packet is transmitted, and at the same time, a CRC calculation is performed. To start.

After the transmission is completed, the destination address, source address, shape size, and data are sequentially transmitted, and then the comparison unit 61 compares the last 4 bytes of the transmitted data with the calculated CRC value. If the result is different, the CRC is transmitted. If not, the time until the next packet is transmitted is measured.

As described above, the apparatus and method for automatically inserting the frame inspection sequence according to the present invention does not need to spend time for calculating the CRC, does not have to put an additional pin, and shortens the time required for data transmission between the switching unit and MACRKS. It is effective.

Claims (2)

MAC transmission first-in first-out unit for temporarily storing data input from the switching unit, preamble for notifying the start of the packet or preamble and jam generating unit for generating data for jamming in case of data collision in the network And a backoff and internal gap timer for measuring the time for retransmission when a data collision occurs in the network, or for measuring the time from one packet transmission to the next packet transmission in the network. A circular margin test (hereinafter referred to as "CRC") generation unit for generating error information about the data; A transmitter comprising a first multiplexer for selecting and outputting one of data input from the preamble and jam generator, a CRC generator, and a MAC first-in first-out unit; A second multiplexer for selecting and outputting one of data input from a first multiplexer of the transmitter or data input from a network; and a MAC reception first-in, first-out unit configured to temporarily store data input from the second multiplexer. After checking whether there is an error in the address CAM to determine who is the destination of the received data or the packet that should not be received, and if there is an error in the received data, the data is passed through the filter to check whether there is an error or failed to pass the filter. An apparatus for inserting a frame check sequence including a receiver configured to ignore CRC and CAM filters, the apparatus comprising: a comparison unit for comparing a predetermined byte of data input from the switching unit with a calculated CRC value and determining whether to attach the CRC accordingly; Frame inspection sequence automatic insertion device, characterized in that configured by. A first step of measuring the time from one packet transmission to the next packet transmission and then determining whether the measured time has reached a set time; A second step of transmitting a preamble indicating the start of a packet when the determination result of the first step is reached, and simultaneously transmitting a destination address, a source address, a shape size, and data after starting a CRC calculation; A third step of determining whether a predetermined byte of data to be transmitted is equal to a calculated CRC value when the execution of the second step ends; And a fourth step of transmitting a CRC if it is different from the third step and returning to the first step if it is not the same.