JPH03196739A - Cell transfer system and communication controller according to the system - Google Patents

Abstract

PURPOSE:To decrease a transmission delay time for retransmission control and to improve the utilizing efficiency and transmission quality by composing a packet frame into plural cells of a prescribed length, sending them and allowing a receiver side to check them in the unit of the cells. CONSTITUTION:A sender side controller 3A outputs plural data having a destination address to a transmission section 4A of a communication controller 2A. The transmission section 4A discriminates data of one and same destination to form one or plural cells. Each cell consists of a header including a destination address and a check bit and a data, the cell is sent to a communication network 5 while being subject to self routing based on the header and reaches a reception section 6B of a communication controller 2B indicated by the destination address. The reception section 6B checks the address and the check bit of the received cell and outputs the result to a controller 3B when there is no error. When any error exists, the controller 3B allows the transmission section 4B to output a retransmission request and the sender side reception 6A receives it and the transmission section 4A reads the cell from the retransmission buffer and sends it to the communication network 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a packet switch, and particularly to a cell transmission system for a communication control device.

(Prior Art) A packet switch transmits packets using frame bits. A frame generally consists of an information section (
■), a destination address section (A), a control section (C), a bit for checking transmission errors, that is, a frame check sequence section fFcsl, and a frame bit (Fcsl);
It consists of each field of l. The communication control device of the exchange receives and receives a plurality of pieces of transmission information from the control device, and assembles a frame from information for the same destination. At this time, the frame length is selected and transmitted so that the transmission efficiency is high or the transmission delay time is shortened. When the communication control device on the receiving side receives this frame, it checks for errors in the bit configuration of the frame using a frame check sequence, and reports the presence or absence of errors to the control device. If an error is detected, the control device performs retransmission control to request the transmitting side to retransmit the frame.

(Problem to be Solved by the Invention) However, in such a packet transmission system, the receiving side device checks for code errors using a frame check sequence when all the information included in the frame is received, and after detecting the error, The system was configured to perform retransmission control, resulting in long transmission delays. Furthermore, in a cell transmission system that replaces packet transmission, a cell error check method that triggers cell retransmission has not yet been established.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cell transfer method and a communication control device using the same, which eliminate the above-mentioned drawbacks, reduce transmission delay time associated with retransmission control, and improve usage efficiency and transmission quality. do.

(Means for Solving the Problems) In the communication control device according to the present invention, when dividing a conventional frame of a packet into one or more cells, check bits such as destination address, cell type, cell number, etc. are added to each cell. Then, a frame check sequence spanning one or more cells is inserted into the final cell. On the receiving side, errors are checked on a cell-by-cell basis and across multiple cells, and if there is an error, retransmission control is performed.

According to the present invention, in a cell transfer method in which cells are transferred between communication control devices on the transmitting side and receiving side, the communication control piece device on the transmitting side selects a single or Configure multiple cells and the header is
The destination of the transmission information, the cell type that indicates one or more formats of the cell configuration, and in the case of multiple cells, the order thereof, the cell number that indicates the order in which the cells are transmitted, the number of bits of the cell, and including inspection information indicating the logical validity of the
The information section of a single cell or the last cell of multiple cells contains frame check sequence information for checking the bit configuration of this single cell or multiple cells, and is used for communication control on the receiving side. When a device receives a cell, it identifies the destination, detects the presence or absence of an error based on the regularity of the order of cell types, the continuity of cell numbers, the number of cell bits, inspection information, and frame check sequence information. When detected, it requests the transmission side communication control device to retransmit the cell corresponding to the error.

Also according to the invention. A communication control device applied to such a cell transfer method is provided.

(Function) On the transmission side, the communication control device according to the present invention assembles 1 or 7I cells from transmission information for the same destination and transmits them to the communication network. The cell includes a header and an information section, and the header includes check information such as the configuration format of one or more cells and the cell order of multiple cells. On the receiving side,
These cells are received and the presence or absence of errors is detected using check information. If an error is detected, the corresponding cell is retransmitted.

(Example) Next, an example of a cell transfer system according to the present invention will be described in detail with reference to the accompanying drawings.

In the cell transfer system according to the present invention, a conventional bucket transmission frame is divided into a plurality of cells of a predetermined length and transmitted, and the receiving side performs an error check on a cell-by-cell basis and performs retransmission flirt fl on a cell-by-cell basis.

FIG. 1 shows a transmission system using a communication control equipment (DCE) to which the present invention is applied. This transmission system is configured such that a transmitting side and a receiving side are interconnected through a communication network 5. In the figure, the transmitting side is shown with a reference numeral A added thereto, and the receiving side is shown with a reference numeral B added thereto.

The transmitting side control device 3A outputs a plurality of pieces of data having destination addresses to the transmitting section 4A of the communication control device 2A.6 The communication section 4A determines data having the same destination and forms one or more cells from them. do. These cells consist of a header containing the destination address and check bits, and data. The transmitter 4A transmits the cell to the communication network 5.

The cell transmitted to the communication network 5 is self-routed within the communication network 5 based on the header contained therein, and arrives at the receiving unit 6B of the communication control device 2B specified by the destination address. The receiving unit 6B checks the address and check bit of the received cell, and if there is no error, outputs it to the control device 3B. If an error is detected, the control device 3B causes the transmitter 4B to output a retransmission request. This is received by the receiving unit 6B of the communication control device 2A on the transmitting side through the communication network 5. The transmitter 4A stores cells that have already been transmitted in a retransmission buffer (not shown), reads out the corresponding cells, and transmits them to the communication network 5. In this way, retransmission control is performed.

FIG. 4 shows the correspondence between the cells used in this embodiment and the packet transmission frames of the conventional method.
Once received, a frame was constructed for information to the same destination, and the information was transferred using this frame. A frame consists of an information section I of a predetermined length or less, a destination address section A, a control section C, and a frame check sequence (F(:S) section,
! 3 and frame bit F.

In this method, the destination address part A, the control part C1, the information part I, and the frame check sequence part F of the conventional frame are
A plurality of cells Sl to Sn corresponding to C3 are provided, and each cell is connected to a switch header 5WI1. In the specific example, the 6-boat header PH, which is composed of a port I'll and a data section D-, has a 2-bit cell seed printing section S, a 3-bit cell number section N, and a cell configuration bit parity bit. ntP,
The remaining 3 bits of 8 comprising part B indicating the number of cell bytes are don't care bits dC1. Furthermore, the final cell S
n includes a frame check sequence FC5 in its data portion Dn.

By Fe2, multiple cells 5I=Sn configuration bit 5N)
1. This realizes checking for transmission errors across Pll and D-.

The communication 18 control device 2 transfers cells S- having one or more formats, and the functional blocks of the transmitting section 4 are shown in FIG. 2, and the receiving section 6 is shown in FIG. 3. These functional blocks will be explained with reference to the transmission procedure shown in FIG.

The transmitting side control device 3A sends the transmission information 11 to In to the transmitting section 4A of the communication control device 2A. This sending information II~
In is the byte v1! that constitutes one frame in the conventional method.
5 and the destination.

Upon receiving this information, the header adding unit 42 of the transmitting unit 4 shown in FIG. 2 adds a cell header 5l containing the destination address.
l11. For example, four configuration cells 5O1S1-S3 are created using the ivy PH and data D to the ports.

In the configuration example of the port header PH in FIG. 4, the cell type bit SB is rill in the cell SO, and in the cell S1.
In S2 and S3, rlOJ rooJ, respectively
"rold". The cell number N is a 3-bit cyclic number "0" to "modulo 8" corresponding to the order of cell transmission.
7”. The parity bit P is set as a parity bit for 16 bits of the pH sent to the port, and the byte number B is set as the number of bytes of the cell. Cell S
O and S3 contain cells SO and 5l-33, respectively.
A frame check sequence FC3 is added to the switch 5IIH and the port PI (and a frame check sequence FC3 for checking the bit configuration of data D- using the CRC method).

Cell assembly section 44 connected to the output side of header addition section 42
Assembles the data and header output by the header adding section 42 into a fixed length cell 5O5St-33 and passes it to the line interface 46. From here, the cells SO and Sl-S3 are sent out to the transmission line 5.

Cell 50. Sl-S3 self-routes through the communication NI 45 to reach the destination communication control device 2B. In the receiving section 6 shown in FIG. 3, a single line interface 62 is provided.

When the cells SO and Sl-S3 shown in FIG. 5 are received from the transmission line 5, they are passed to the cell disassembly section 64. Cell disassembly section 64
checks whether the destination address included in the Sui-Sochi header SWH of these cells S0.51 to S3 matches the local station address, decomposes the data into a header and data D, and sends the data to the header check section 66.

The header check section 66 has a cell order check circuit illustrated in FIG.
This is inverted by an inverter 21 and inputted to a shift register fsRG) 20. Then, the AND gate 2 checks the consistency between the upper bits of this S8 bit and the lower bits of the previous SB bit output from the shift register 20.
Check by 2. Specifically, in this example, cell S
1, SO bits of S2 and S3 are NOJ respectively
Since roOJ rolJ, the inverted bits become roll rill rlOJ, and the upper bits and lower bits of successive inverted bits match.

This check determines the continuity of cells St to S3.

FIG. 7 shows an example of a cell number check circuit included in the header check section 66. The cell number N of the port PH is cell 5O1S1. In S2 and S3, "mouth DOJ rooo J rool J rolo" respectively.
It is J.

The gate 26 receives the output of the RGI 25 and the number N, and when the two match, selects the logic rlJ to the selector 27.
output to input A of The selector 27 is connected to this gate 26
[0] is always input to the output and input B, and the cell type SB of the ivy PH is input to the switching port C.

The selector 27 outputs the state of the input B, that is, the logic "0", when the cell type SO indicates "00" and "0 month", and outputs the logic state of the human power A in other cases. . The register 25 receives and holds the output of the selector 27, and outputs it. The initial value of register 25 is rooo J.

First, when a cell Sl is input, the gate 26 compares the cell number "0" with the initial value r000J of the register 25 and outputs a logic "1". Since the cell type SB is "lO", the selector 27 outputs the logic r14 of the human power A, and the register 25 is thereby divided by 1. Next, when cell S2 is input, its cell number N roll J
is checked by gate 26. Further, in the cell S3, the cell number N rool J is checked, and the contents of the register 25 become rooo J, thereby preparing for input to the next cell Sl or SO.

The header check section 66 further includes a parity check circuit, an example of its configuration is shown in FIG. This is the 16 bits that make up the ladder PH to the boat, i.e. the cell type SO
, don't care d, c1, cell number N, parity P, and odd parity of byte I&H.
If the check result is an odd number, the gate 28 outputs a logic "l" to indicate normality.

(Effects of the Invention) According to the present invention, a conventional packet frame is assembled into a plurality of cells of a fixed length and transmitted, and the receiving side checks the cells in units of cells.

Early detection of errors enables early processing, and the delay time of error retransmission control including retransmission can be reduced. Also.

Error detection by hardware reduces the load on the control device and releases the five reception buffers at the time of error detection, improving usage efficiency and improving transmission quality.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a transmission system showing an embodiment of the cell transmission system according to the present invention, and FIGS. 2 and 3 show the transmitting section and receiving section, respectively, of the communication control device in the embodiment shown in FIG. Functional block diagram. FIG. 4 is an explanatory diagram showing a comparison between a conventional frame and a cell in this embodiment. FIG. 5 is an explanatory diagram showing an example of a transmission procedure in the embodiment, and FIG. 6 is a circuit diagram showing an example of the configuration of a cell order check circuit included in the header check section of the receiving section shown in FIG. 3. FIG. 7 is a circuit diagram showing an example of the structure of a cell number check circuit included in the header check section, and FIG. 8 is a circuit diagram showing an example of the structure of a parity check circuit also included in the header check section. 66°, header addition part

Claims (1)

[Claims] 1. In a cell transfer method in which cells are transferred between communication control devices on a transmitting side and a receiving side, the communication control device on the transmitting side includes a header and an information part from transmission information for the same destination. one or more cells are configured, and the header indicates the destination of the transmission information, one or more formats of the cell configuration, and in the case of multiple cells, the cell type indicating the order, and the cell type for transmitting the cells. The information section of a single cell or the last cell of multiple cells includes a cell number indicating the order, the number of bits of the cell, and check information indicating their logical validity. It includes frame check sequence information for checking the bit configuration of one cell or the plurality of cells, and when the communication control device on the receiving side receives the cell,
The destination is identified, and the presence or absence of an error is detected based on the regularity of the order of the cell types, the continuity of the cell numbers, the number of bits of the cells, the inspection information, and the frame check sequence information, and when an error is detected. , a cell transfer method that requests the transmission side communication control device to retransmit the cell corresponding to the error. 2. In a communication control device that transfers cells, the device includes: a transmitter that configures and outputs one or more cells including a header and an information section from transmission information to the same destination; and a transmitter that communicates cells from the transmitter. and interface means for transmitting the transmission information to a network, the transmitting means displays one or more formats of cell configurations for the transmission information, and in the case of multiple cells, the cell type indicating the order and the order in which the cells are transmitted. generate a cell number indicating the cell number, the number of bits of the cell, and check information indicating their logical validity; configure the header including these information and the destination of the transmitted information; 1
Alternatively, form the information part of a plurality of cells, and generate frame check sequence information for checking the bit configuration over the one or more cells in the information part of the last cell, and A communication control device characterized in that it has a header assembling means added to the information part of the final cell. 3. In a communication control device that transfers cells, the device has a receiving means for receiving from a communication network one or more cells including a header and an information part formed from transmission information for the same destination, and the header includes: , the destination of the transmission information, the cell type that displays one or more formats of the cell configuration, and in the case of multiple cells, the order thereof, the cell number that indicates the order in which the cells are transmitted, and the number of bits of the cell. , check information indicating their logical validity; including frame check sequence information for checking, the receiving means: a cell disassembly means for disassembling a cell from the communication network into the header and an information part; identifying a destination from the header from the cell disassembly means; A header that checks cell regularity based on the cell type, cell number, cell bit number, and inspection information, and checks the one or more cells based on frame check sequence information in the information section of the final cell to detect errors. A communication control device comprising: a checker; and, when the header checker detects an error, a request is made to a transmitting side of the cell to retransmit the cell corresponding to the error.