ATM switch using cell division

Abstract: The present invention relates to an ATM cell switch system in a broadband ISDN, and specifically to an ATM cell switch system where the number of a header part as a destination data of a cell except header error control data and the number of an information part have a common divisor. To realize a switch circuit in a hierarchical structure applicable to an LSI system, the circuit comprises an ATM cell divider (10) for dividing an ATM cell into unit cells each having a 1-bit header part or sub-cells each having a multi-bit header part, an ATM cell switch (11) for switching said unit cells or sub-cells according to the header data, and an ATM cell output unit (12) for assembling an ATM having a header part corresponding to the number of output lines of the switch circuit and outputting the result from said corresponding output lines.

Description: The present invention relates to an asynchronous transmission mode (ATM) cell switch system in a broadband ISDN, and specifically to an ATM switch circuit configuration system for switching an ATM cell after dividing it into a plurality of sub-cells or unit cells. An ATM switch transmits fixed-length ATM cells, as of a fixed length, to an opposite state in cells at a high speed according to header information. Therefore, an appropriate ATM switch circuit configuration system is required for realizing an LSI system. In an asynchronous transmission mode (ATM) system for a broadband ISDN transmission, the transmission speed of subscribers' lines is 155.52 Mbits/s or four times that speed, and data are transmitted after being divided into fixed length blocks called "an ATM cell". Figure 1 shows an example of a configuration of an ATM cell. In Figure 1, the length of an ATM cell 1 is a total of 53 bytes, 5 bytes of which are used as a header field 2 indicating the cell's destination, and 48 bytes are used as an information field 3 for transmission data. The last 1 byte of the header field 2 stores header error control data and is used for header error control (HEC). Figure 2 shows an example of a configuration of a broadband ISDN system. In Figure 2, digitized information of voice, data and images are divided into fixed length ATM cells having a header indicating a destination, etc., and then transmitted through a transmission circuit 6 by an ATM switch 5. On the receiving side, an ATM cell is switched by an ATM switch 7 and directed to a correspondent user terminal 8. One conventional ATM circuit system is a multi-step gate type system. Figure 3 shows a configuration of a single-input multi-step gate type system. In a multi-step gate type system, 1x2 unit switches are arranged orderly to allot one ATM cell. A unit switch in the first step works at the first bit data of the header field; a unit switch in the second step works at the second bit data of the header field; and a unit switch in the Nth step works at the Nth bit data of the header field. Thus, each unit switch automatically works according to the value of each header field to allot an ATM cell. Figure 4 shows an example of a configuration of a single input multi-step gate type system (N=3). In this example, an inputted ATM cell has a 3-bit header part. For example, if an ATM cell having a header 011 (the first three bits) is inputted, 1x2 unit switches work after checking each bit, thus outputting the ATM cell to an output terminal 4. To allot a plurality of ATM cell inputs in a multi-step gate type system, 2x2 unit switches must be arranged in an orderly manner; a unit switch in the first step works at the first bit data of the header field; a unit switch in the second step works at the second bit data of the header field, and a unit switch in the Nth step works at the Nth bit data of the header field. Thus, each unit switch works automatically according to the value of each header field to allot ATM cells. Figure 5 shows a configuration of a multi-input multi-step gate type circuit. Figure 6 shows an example of a configuration of a multi-input multi-step gate type circuit. In this example, an inputted ATM cell has a 3-bit header part. For example, if an ATM cell having a header 011 (the first three bits) is inputted, 2x2 unit switches work after checking each bit, thus outputting the ATM cell to an output terminal 4. As shown in Figure 6, a unit switch of each step is connected such that any ATM cell having the same header part can be outputted to the same output terminal even if it is inputted from different input lines. In a multi-step gate type system in an ordinary ATM switch circuit system shown in Figures 3 - 6, cells having the same header data value is outputted to the same output terminal according to the wiring among 1x2 or 2x2 unit switches. As all headers except a header error control data are, for example, 32 bits long, the number of gate steps are 32; the number of basic unit switches of a single input multi-step gate type system is equal to the number of output lines - 1; and the number of basic unit switches of a multiple input multi-step gate type system is equal to the number of input/output lines x 32/2. Thus, the number of unit switches increases with the number of input/output lines. As the configuration is not in the hierarchical structure, the increase of input/output lines (a maximum of 2³²) requires the addition of basic unit switches and extended modification of the connection among basic unit switches, thus making it very difficult to realize an LSI system. EP-A-0 320 714 describes a communication system in which the cells of a packet are simply divided. Therein, the header part is concentrated on the divided first cell. Summary of the Invention An object of the present invention is to realize an ATM cell switch circuit in a hierarchical structure applicable to an LSI system. A feature of the present invention resides in an asynchronous transmission mode (ATM) switch circuit configuration system comprising an ATM cell dividing means, a unit cell switching means and a plurality of ATM cell assembly output means. The ATM cell dividing means for dividing an ATM cell comprising header part data and information part data excluding header error control data respectively by the number of data bits of said header into a plurality of unit cells comprising a 1-bit header part and a divided information part, and for outputting said unit cells from an equal number of output terminals as the divisor. The unit cell switching means comprises input terminals corresponding to a plurality of output terminals of said ATM cell dividing means for outputting unit cells inputted by said ATM cell dividing means to either of two output terminals corresponding to each of said input terminals according to the value of header data of said unit cell. An ATM cell assembly output means is provided for each of t output lines of said ATM switch circuit. The output means comprises input terminals where half the outputs of a plurality of output terminals of said unit cell switching means are inputted according to each header value of an ATM cell to be outputted, wherein all the unit cells are assembled and outputted as an ATM cell when unit cells are inputted from said unit cell switching means to all the input terminals. Brief Explanation of Drawings Figure 1 shows an example of a configuration of an ATM cell; Figure 2 shows an example of a configuration of a broadband ISDN system; Figure 3 shows a configuration of a single-input multi-step gate type circuit; Figure 4 shows a configuration of a single input multi-step gate type circuit (N=3); Figure 5 shows a configuration of a multi-input multi-step gate type circuit; Figure 6 shows a configuration of a multi-input multi-step gate type circuit in case of N=3; Figure 7A shows a block diagram for explaining the first principle; Figure 7B shows a block diagram for explaining the second principle; Figure 7C shows a block diagram for explaining the third principle; Figure 7D shows a conceptual view for explaining the first to third principles; Figure 7E shows a block diagram for explaining the fourth principle; Figure 8 shows a block diagram for explaining the configuration of the first principle; Figure 9 shows an output signal of an ATM cell divider in an embodiment of the first principle; Figure 10 shows a configuration of an ATM cell switch and an ATM cell output unit; Figure 11 shows a circuit configuration of an ATM cell divider in an embodiment in the first principle; Figure 12 shows a time chart for explaining the division of cells by an ATM cell divider in an embodiment of the first principle; Figure 13 shows a circuit configuration of an ATM unit cell processor in an embodiment of the first principle; Figure 14 shows a time chart for explaining the switch of cells by an ATM unit cell processor in an embodiment of the first principle; Figure 15 shows a circuit configuration of an ATM cell composer in an embodiment of the first principle; Figure 16 shows a time chart for explaining the assembly of a cell by an ATM cell composer in an embodiment of the first principle; Figure 17 shows a block diagram of a configuration in an embodiment of the second principle; Figure 18 shows an example of an output signal of an ATM cell divider in an embodiment of the second principle; Figure 19 shows a block diagram for explaining a configuration of an ATM cell switch and an ATM cell output unit in an embodiment of the second principle; Figure 20 shows a circuit configuration of an ATM cell divider in an embodiment of the second principle; Figure 21 shows a time chart showing the division of cells by an ATM cell divider in an embodiment of the second principle; Figure 22 shows an example of a circuit configuration of a primary ATM sub-cell processor in an embodiment of the second principle; Figure 23 shows a circuit configuration of an ATM cell composer in an embodiment of the second principle; Figure 24 shows a time chart for explaining the division of cells by an ATM cell composer in an embodiment of the second principle; Figure 25 shows a block diagram for explaining a configuration of an embodiment of a (q-1)th ATM sub-cell processor in an embodiment of the third principle; Figure 26 shows an embodiment of an output signal of the qth ATM sub-cell divider in the third principle; Figure 27 shows a block diagram for explaining an example of a configuration of a secondary ATM sub-cell switch and a secondary ATM sub-cell output unit in an embodiment of the third principle; Figure 28 shows a circuit configuration of a secondary ATM sub-cell divider in an embodiment of the third principle (in a primary sub-cell processor); Figure 29 shows a time chart for explaining the division of primary sub-cells by a secondary ATM sub-cell divider in an embodiment of the third principle; Figure 30 shows a circuit configuration of a secondary ATM sub-cell processor in an embodiment of the third principle (in a primary sub-cell processor); Figure 31 shows a time chart for explaining the switch of sub-cells by a secondary ATM sub-cell processor in an embodiment of the third principle; Figure 32 shows a circuit configuration of a secondary ATM sub-cell composer in an embodiment of the third principle (in a primary sub-cell processor); Figure 33 shows a time chart of the assembly output of primary sub-cells by a secondary ATM sub-cell composer in an embodiment of the third principle; Figure 34 shows a block diagram for explaining the configuration of an embodiment of the fourth principle; Figure 35 shows a block diagram for explaining an embodiment of a multiplexer of the fourth principle; Figure 36 shows an example of an output signal of an ATM cell divider in an embodiment of the fourth principle; Figure 37 shows an embodiment of a signal of a multiplexer in an embodiment of the fourth principle; Figure 38 shows a circuit configuration of a multiplexer in an embodiment of the fourth principle; and Figure 39 shows a time chart of multiplexing primary sub-cells by the multiplexer in an embodiment of the fourth principle. Embodiment Figures 7A to 7E show block diagrams for explaining the principles of the present invention. It explains how an ATM switch circuit is confilgured in the broadband ISDN asynchronous transmission mode (ATM) cell switch system. Figure 7A is a block diagram for explaining the first principle of the present invention; where an ATM cell divider 10 divides an ATM cell excluding header error control data. It divides each of a 32-bit header part and a 384-bit information part into 32 parts, thus generating 32 unit cells each comprising a 1-bit header part and a 12-bit information part and outputting these unit cells from 32 output terminals respectively. A unit cell switch 11 is provided with 32 input terminals corresponding to 32 output terminals of the ATM cell dividers 10. Unit cells are inputted to these 32 input terminals. According to the header value of each unit cell inputted from the ATM cell divider 10, each unit cell is outputted to either of two output terminals also provided in the unit cell switch means 11 corresponding to each input terminal. Therefore, a total of 64 output terminals are provided therein. The unit cell switch means 11 comprises, for example, 32 units of 1x2 switches, each switch outputting an ATM unit cell to either of two output terminals corresponding to each input terminal according to the header value of 0 or 1. ATM cell assembly output means 12₁, 12₂,---, 12 t are provided according to the number t of output lines of the switch circuit. An ATM cell assembly output means comprises 32 input terminals. The values in a 32-bit header of an ATM cell are outputted to the output lines of the unit cell switch means. According to these values, 32 out of 64 output terminals of the unit cell switch means 11 are connected to the input terminals of ATM cell assembly means. The 32 unit cells are assembled and outputted to the output line as an ATM cell when unit cells are inputted from the unit cell switch means 11 to all of 32 input terminals. A buffer, for example, is connected as a unit cell input part to each of 32 input terminals of an ATM cell assembly output means . When unit cells are stored in all of 32 buffers, the unit cells are assembled into an ATM cell by an assembler for assembling an ATM cell, and then outputted. Figure 7B shows a block diagram for explaining the second principle of the present invention. In Figure 7B, a primary sub-cell divider 13 divides the above described 32 bit header part and 384 bit information part by e₁, a divisor of 32 except 1 and 32, thus dividing an ATM cell into e₁ primary sub-cells each comprising an f₁ (f₁=32/e₁)-bit header part and a g₁ (g₁=384/e₁)-bit information part, and then outputs each of primary sub-cells from e₁ output terminals. A primary sub-cell switch means is are provided with e₁ input terminals corresponding to e₁ output terminals of the primary sub-cell divider 13. Primary sub-cells are inputted to these e₁ input terminals. According to the header value of each primary sub-cell inputted from the primary sub-cell divider 13, each primary sub-cell is outputted to one of 2 f1 output terminals also provided in the primary sub-cell switch means 14 corresponding to each input terminal. A total of 2 f1 x e¹ output terminals are provided therein. The primary sub-cell switch means 14 comprises, for example, e¹ primary sub-cell processors. Signals from e¹ output terminals in the primary sub-cell divider 13 are inputted to each primary sub-cell processor. The primary sub-cell processor comprises, 2 f1 output terminals. For example, if f₁ is 4, it comprises 16 output terminals, and the primary sub-cells inputted to input terminals are outputted to one of 16 output terminals according to the header value of each primary sub-cell. ATM cell assembly output means 15₁, 15₂, --- 15 t are provided according to the number t of output lines of the switch circuit. Each ATM cell assembly output means comprises e₁ input terminals, and e₁ out of 2 f1 x e₁ output terminals in the primary sub-cell switch means 14 are connected to respective input terminals respectively. When primary sub-cells from the primary sub-cell switch means 14 are inputted to all the above described input terminals, the e₁ primary sub-cells are assembled to an ATM cell and outputted to an output line. Each of the ATM cell assembly output means comprises an ATM cell input part connected to e₁ input terminals and an assembler for assembling these primary sub-cells when they are inputted to all of the ATM cell input parts and for outputting them to the output line as an ATM cell. Figure 7C is a block diagram for explaining the third principle of the present invention. In Figure 7C, a q-1th sub-cell switch means 16 (when q=2) corresponding to the primary sub-cell switch means 14 comprises e₁ primary sub-cell processors (16₁, 16₂, -- - 16 e1 ) for outputting primary sub-cells inputted by the primary sub-cell divider 13 to any of 2 f1 output terminals according to the header value of the primary sub-cell after signals are inputted from e₁ output terminals of the primary sub-cell divider 13. In the primary sub-cell processor means (16₁, 16₂, --- 16e₁), the secondary sub-cell divider 17 divides a primary sub-cell comprising an f₁-bit header part and a g₁-bit information part, by e₂, a divisor of e₁ other than 1 and e₁, thus dividing a primary sub-cell into e₂ secondary sub-cells each comprising an f₂ (f₂=f₁/e₁)-bit header part and a g₂ (g₂=g₁/e₁)-bit information part, and outputs each of secondary sub-cells from e₂ output terminals. A secondary sub-cell switch means 18 comprises e₂ secondary sub-cell processors (16₁, 16₂, ---16 e1 ) for receiving secondary sub-cells from the secondary sub-cell divider 17 and outputting the secondary sub-cells to any of 2 f2 output terminals according to the header value of each secondary sub-cell. Secondary sub-cell assembly output means (19₁, 19₂, --- 19 t2 ) are provided corresponding to the number t₂ (t₂=2 f1 ) of 2 f1 output terminals, each comprising e₂ output terminals where e₂ outputs out of 2 f2 x e₂ output terminals in the secondary sub-cell switch means 18 are inputted according to the header value of a primary sub-cell to be outputted to the above described output terminal of a secondary sub-cell assembly output means, assemble e₂ secondary sub-cells when secondary sub-cells are inputted from the secondary sub-cell switch means 18 to all of e₂ input terminals, and output them as primary sub-cells to the ATM cell assembly output means. Generally, in q-lth (q≥3) sub-cell processors (16₁, 16₂, --- 16 eq-1 ), the qth sub-cell divider 17 divides a q-lth sub-cell comprising an f q-1 -bit header part and a g q-1 -bit information part by e q , a divisor of e q-1 other than 1 and e q-1 into e q qth sub-cells each comprising an f q (f q =f q-1 /e q )-bit header part and a g q (g q =g q-1 /e q )-bit information part, and outputs qth sub-cells from e q output terminals. The qth sub-cell switch means 18 comprises e q qth sub-cell processors for receiving qth sub-cells from the qth sub-cell divider 17 and outputting qth sub-cells from any one of 2 fq output terminals according to the header value of a qth sub-cell. Qth sub-cell assembly output means (19₁, 19₂, -- - 19 tq ) are provided corresponding to the number f q-1 of output lines of sub-cell processors, comprise e q input terminals where e q outputs out of 2 fq x e q output terminals in the qth sub-cell switch means 18 are inputted according to the header value of a q-lth sub-cell to be outputted to the above described output line of a q-lth sub-cell processor, assemble e q qth sub-cells when qth sub-cells are inputted to all e q input terminals from the qth sub-cell switch means, and then output them as q-1th sub-cells. Thus, the qth sub-cell processors are sequentially configured in a hierarchical structure with the value of "q" increased. Figure 7D shows a supplementary view for explaining the above described first to third principles of the present invention. In Figure 7D, in the first principle, a switch circuit comprises an ATM cell divider 10a corresponding to the ATM cell divider 10 in Figure 7A, an ATM cell switch means 11a corresponding to the unit cell switch means 11 in Figure 7A, and an ATM cell output means 12 comprising ATM cell assembly output means 12₁, --- 12 t . The ATM cell switch means 11a comprises a plurality of ATM unit cell processors 11₁ 11₂, --- for outputting inputted unit cells to either of two output terminals. The ATM cell output means 12 comprises ATM cell composers 12a, 12b, --- corresponding to the ATM cell assembly output means. By contrast, in the second principle shown in Figure 7D, a switch circuit comprises an ATM cell divider 13a corresponding to the primary sub-cell divider 13, an ATM cell switch means 14a corresponding to the primary sub-cell switch means 14, and an ATM output means 15 comprising ATM cell composers 15a, 15b, --- corresponding to the ATM cell assembly output means 15₁, ---, 15 t . In the first principle, an ATM cell is divided into unit cells each having a 1 bit header by the ATM cell divider 10a, switched by the ATM cell switch means 11a, assembled by the ATM cell output means 12, and then outputted. However, in the second principle, an ATM cell is divided into primary sub-cells having a multiple-bit header part, and then switched and outputted. It is possible to configure an ATM primary sub-cell processor 14₁, 14₂, --- in a multi-step gate type circuit as shown in Figures 3 and 4. In this case, however, there is a problem that it is not sufficiently applicable to an LSI system. The third principle has been developed to solve this problem and configure the primary ATM sub-cell processor more progressively in a hierarchical structure. In the third principle shown in Figure 7D, a ATM primary sub-cell processor 14₁ comprises a ATM secondary sub-cell divider 17a corresponding to the qth sub-cell divider 17 shown in Figure 7C, a ATM secondary sub-cell switch means 18a corresponding to the qth sub-cell switch means 18, and an ATM secondary sub-cell output means 19 comprising the qth sub-cell assembly output means 19₁, 19₂, ---. An ATM secondary sub-cell switch means 18a comprises a plurality of ATM secondary sub-cell processors 18₁, 18₂, ---like the ATM cell switch means 14a in the second principle, each of the ATM secondary sub-cell processors having a hierarchical configuration just like the ATM primary sub-cell processor. If the ATM secondary sub-cell processor has only two output terminals like the ATM unit cell processor in the first principle, sub-cells inputted in this processor will be unit cells, thus configuring the processor with basic 1x2 switches. Therefore, no further hierarchical structure is required. Figure 7E shows a block diagram for explaining the fourth principle of the present invention. In Figure 7E, primary sub-cell dividers 21₁, 21₂, --- 21 W are provided corresponding to the number w of ATM cell input lines to be used in a switch circuit. An ATM cell comprising a 32-bit header part and a 384-bit information part excluding the header error control data in the ATM cell is divided by e₁, a divisor of 32 other than 1 and 32, thus being divided into e₁ primary sub-cells each comprising an f₁ (f₁=32/e₁1-bit header part and a g₁ (g₁=384/e₁)-bit information part, and then outputted from e₁ output terminals respectively. Primary sub-cell multiplexers 22₁, 22₂, --- 22 e1 are provided corresponding to the number e₁ of output terminals of each of the primary sub-cell dividers 21₁, 21₂, --- 21 W , and the multiplex primary sub-cells, to be outputted from a plurality of primary sub-cell dividers 21₁, 21₂, --- 21 W , located at the same relative position in an ATM cell. The operation of a primary sub-cell switch means 23 is the same as that of the primary sub-cell switch means 14 in the second principle of the present invention shown in Figure 7B. That is, the primary sub-cell switch means 23 outputs primary sub-cells outputted simultaneously from the primary sub-cell multiplexers 22₁, 22₂, --- 22 e1 from any of 2 f1 output terminals corresponding to e₁ input terminals. The operation of ATM cell assembly output means 24₁, 24₂, --- 24 t is the same as that of the ATM cell assembly output means 15₁, 15₂, --- 15 t shown in Figure 7B. That is, each of the ATM cell assembly output means outputs primary sub-cells when primary sub-cells are inputted from the primary sub-cell switch means 23 to all of the e₁ input terminals, and then outputs them to each of the output lines as an ATM cell. According to the first principle shown in Figure 7A, a header part of an ATM cell is divided into 1-bit unit cells, each unit cell being inputted to, for example, a 1x2 unit switch forming a unit cell switch means 11. From each unit switch, a unit cell is outputted from the output L₀ when the header value is 0, and from the output L₁ when the header value is 1. The ATM cell assembly output means 12₁, 12₂, ---12 t are, corresponding to the values of a 32-bit header part of an ATM cell to be outputted to output lines, connected to 32 output terminals of 1x2 unit switches in the unit cell switch means 11. For example, all the output terminals L₀ of 1x2 unit switches in the unit cell switch means 11 are connected to the ATM cell assembly output means corresponding to the output lines of 32 header bits of 0. Thus, if all the 32 bits of a header part of an ATM cell inputted by the ATM cell divider 10 are 0, the cell is outputted from this output line. According to the second principle shown in Figure 7B, an ATM cell is divided into primary sub-cells having a multiple-bit header part. In the primary sub-cell switch means 14, primary sub-cells are inputted to e₁ (equal to the number of primary sub-cells) primary sub-cell processors, and outputted from one of 2 f1 output terminals according to the header value of a sub-cell. For example, if a primary sub-cell whose header part f₁ bits are all 0 is outputted from the output terminal L₀ of each primary sub-cell processor, signals from e₁ output terminals L₀ of the primary sub-processor of the primary sub-cell switch means 14 are inputted to the ATM cell assembly output means connected to output lines corresponding to all the 32 bit header values of 0. Thereby, ATM cells having a 32-bit header part of 0 inputted to the primary sub-cell divider 13 are outputted from these output lines. In the third principle shown in Figure 7C, a header part and an information part of a primary ATM sub-cell is divided by e₂ (e₂ is a divisor of e₁ other than 1 and e₁, thus dividing a primary sub-cell into secondary sub-cells without using a multi-step gate type circuit as a conventional ATM cell switch system in the configuration of a primary ATM sub-cell processor. In the secondary sub-cell switch means 18 (q=2), secondary sub-cells are inputted to e₂ (equal to the number of secondary sub-cells) secondary sub-cell processors, and outputted from any of 2 f2 (f₂=f₁/e₂) output terminals according to the header value of a sub-cell. For example, if a secondary sub-cell having whose header part f₂ bits are all 0 is outputted from output terminals L₀ of each secondary sub-cell processor, signals from e₂ output terminals L₀ of the secondary sub-cell processor in the secondary sub-cell switch means 102 are inputted to the secondary sub-cell assembly output means connected to output lines corresponding to f₁ bit header values of 0. Thereby, a primary sub-cell whose header part f₁ bits are all 0 is outputted. A q-lth sub-cell processor (q≥3) can be configured in the above described manner. In the fourth principle shown in Figure 7E, ATM cells inputted from a plurality of input lines are switched. An ATM cell inputted from each input line is divided into primary sub-cells by the primary sub-cell dividers 21₁, 21₂, --- as in the second principle of the present invention. Then, the primary sub-cells at the same relative position in an ATM cell inputted from a plurality of input lines are multiplexed by a primary sub-cell multiplexer, and then inputted as serial signals to the primary sub-cell switch means 23. e₁ primary sub-cells simultaneously inputted to the primary sub-cell switch means 23 are outputted from any of 2 f1 output terminals corresponding to each input terminal according to the header value of a primary sub-cell as in the second principle of the present invention. Then, these primary sub-cells are assembled by the ATM cell assembly output means, and outputted to output lines corresponding to each value in 32 header bits. As described above, in the first principle, for example, an ATM switch circuit comprises an ATM cell divider 10, a unit cell switch means 11 comprising 32 unit cell processors, and ATM cell assembly output means 12₁, 12₂, --- 12 t corresponding to respective output terminals in a hierarchical structure, and is applicable in an LSI system. When the number of output lines are increased, only an ATM cell assembly output means which is connected to a unit cell switch means 11 according to the data in 32 header bits corresponding to each line must be added, and no other wiring modification is required. Figure 8 shows a block diagram of the configuration of the first principle of the present invention. The embodiment shown in Figure 8 comprises an ATM cell divider 25, an ATM cell switch 26, and an ATM cell output unit 27. The ATM cell divider 25 divides an ATM comprising a 32-bit header part and a 384-bit information part excluding the HEC of an ATM cell into 32 ATM unit cells (P₁, P₂, --- P₃₂) each comprising a 1-bit header part H j (j=1-32) and an 12-bit information part K j (j =1-32) , and then outputs each unit cell from each output b j (j=1-32). Each of ATM unit cell processors comprises 1x2 switches, has outputs L₀ and 1¹, and allots ATM unit cells to outputs L hj (L₀ or L₁) according to values h j of a header part H j . The ATM cell switch 26 comprises 32 ATM unit cell processors (Q₁, Q₂, --- Q₃₂). Each Q j (j=1-32) is connected to b j (j=1-32), and an ATM unit cell P j (j=1-32) is inputted to an ATM unit cell processor. Each ATM cell composer forming the ATM cell output unit 27 comprises 32 13-bit ATM unit cell (each comprising a 1-bit header part and a 12-bit information part) input units (R₁, R₂, --- R₃₂) and assemblers for assembling an ATM cell only when ATM unit cells are inputted to all of ATM unit cell input units (R₁, R₂, --- R₃₂). In each of ATM cell composers S n (n=1-T), the ATM cell output unit 27 comprises T (S₁, --- S T ) (T: number of output lines) ATM cell composers. As to the ATM cell assembley unit Sn (n=1 T), the ATM cell having the header value (h₁, h₂, --- h₃₂) is outputted to the output C j of the ATM cell output unit by inputting the output L hj of the ATM unit cell processor Q j (j=1-32) to the ATM unit cell input unit R j (j=1-32) according to the ATM cell header value (h₁, h₂, --- h₃₂) expected by an output line. Figure 9 shows an example of an output signal of an ATM cell divider of an embodiment of the first principle of the present invention. In Figure 9, a 4-byte header part is divided into 1-bit headers and a 48-byte (384-bit) information part is divided into 12-bit information, and the resultant 32 unit cells are outputted from the ATM cell divider 25. Figure 10 shows an example of a configuration of the ATM cell switch 28 and the ATM cell output unit 29 when, in the first principle, an ATM has a 4-bit header part. For example, if an ATM cell having 4 header bits (H₁=1, H₂-H₄=0 respectively) is inputted, unit cells allotted by the ATM cell switch 28 are assembled by assemblers of the ATM cell assembler S₂ and outputted to an output line C₂ as an ATM cell. Figure 11 shows a circuit configuration of an ATM cell divider in an embodiment of the first principle. In Figure 11, an ATM cell divider comprises a serial-in/parallel-out shift register 31 where ATM cells are serially inputted, 32 parallel/serial switches 32₁, --- 32₃₂ where a part of parallel outputs of a serial-in/parallel-out shift register 31 are inputted and unit cells are outputted, and an inverter 33 for generating inverse signals of a clock. Figure 12 shows a time chart for explaining the division of cells by the ATM cell divider shown in Figure 11. The operation of the ATM cell divider is explained below in association with Figures 11 and 12. In Figure 11, an ATM cell is applied to serial input terminals of the serial parallel switch 31 and inputted in a bit synchronously with an inverse signal of the clock. As an ATM cell comprises 424 bits, a total of 424 clocks are required to input a whole cell. When a whole cell is inputted, load signals are inputted to 32 parallel/serial switches 32₁, --- 32₃₂, and thus data are inputted from the serial-in/parallel-out shift register 31 to these switches. Parallel-inputted data are those in the leading 1 bit in the header part and the leading 12 bits in the information part, in the case of a parallel/serial switch 32₁ for example. In addition, another 1 bit is inputted to indicate the existence of cell data to be used during the assembly by the cell assembler. Then, unit cells parallel-inputted to each of parallel/serial switches 32₁, --- 32₃₂ are outputted from output lines b₁, --- b₃₂ synchronously with a clock signal. This unit cell comprises a total of 14 bits; a 1-bit header part, a 12-bit information part, and an additional bit to be used for determining the existence of a cell. The header error control data (HEC) applied to the serial-in/parallel-out shift register 31 are added at the sending side of ATM cells, and these data are already checked for transmission error prior to inputtng to the ATM switch circuit, thus requiring no additional process at an ATM cell divider. When cells are assembled and outputted by an ATM cell composer, the HEC must be added as described later. Figure 13 shows a circuit configuration of the ATM unit cell processor in an embodiment of the first principle. In Figure 13, the unit cell processor comprises a selector 34 for outputting inputted unit cells to either of two output terminals, a D flip flop 35 for outputting a selection control signal to the selector 34, a D flip flop 37 for outputting the contents of unit cells in a bit to the selector 34 synchronously with an inverse signal of the clock generated by the inverter 36. Figure 14 shows a time chart for explaining the switch of cells by the unit cell processor shown in Figure 13. The operation of the unit cell processor is explained below with resference to Figures 13 and 14. As shown in Figure 13, the contents of unit cells are inputted in a bit to the D flip flop 37 synchronously with an inverse signal of the clock. The first 1 bit of a unit cell is a header part. The value of the header part "1" or "2" determines to which output terminal of the selector 34 the whole unit cell is to be outputted. That is, in Figure 13, a header clock is applied to the D flip flop 35 when 1-bit header part is inputted, thus outputting a selection control signal to the selector 34. When the header part indicates "1", the selection control signal also indicates "1", causing the selector to be switched to the output terminal L₁. When the header part indicates "0", the selection control signal also indicates "0", and the selector is switched to the output terminal L₀. Thus, the switch of the selector is completed, and the whole unit cells are outputted to either of two output terminals of the selector 34. Figure 15 shows a circuit configuration of the ATM cell composer in an embodiment of the first principle. As shown in Figure 15, the cell composer comprises an HEC operating unit 39 for generating header error control data (HEC) when a total of 32 bits of header parts of all unit cells are inputted to a parallel/serial switch 41 to be described later and outputting them to the parallel/serial switch 41, 32 serial/parallel switches 40₁, --- 40₃₂ to which unit cells are serial-inputted from the ATM cell switch 26, a parallel/serial switch 41 to which parallel outputs of these serial/parallel switches are inputted and ATM cells are outputted to output lines, an AND gate 42 to which all bits indicating the existence of cells in unit cells are inputted from 32 serial/parallel switches, an AND gate 43 to which outputs of the AND gate 42 and data load signals to the parallel/serial switch 41 are inputted, and an inverter 44 for generating an invert signal of the clock. Figure 16 shows a time chart for explaining the assembly of a cell by the cell composer shown in Figure 15. The operation of the cell composer is explained below in association with Figures 15 and 16. As shown in Figure 15, each of unit cells outputted from the ATM cell switch is serial-inputted in a bit to 32 cell input units 40₁, --- 40₃₂ synchronously with an inverse signal of the clock. A unit cell comprising a 1-bit header part, a 12-bit information part, and another 1 bit indicating the existence of a cell is inputted into respective input units during the 14 clock periods. Of the inputted data, the last 1 bits, that is, the bits indicating the existence of a cells are all outputted to the AND gate 42. When all these bits indicate "1", referring to the existence of cells, the output of the AND gate is "H". Then, the data load signal to the parallel/serial switch 41 is "H" as shown in Figure 16, and data are parallel-inputted to the parallel/serial switch 41. At this time, the parallel-inputted data comprises a total of 13 bits; a 1-bit header part and a 12-bit information part from, for example, the cell input unit 40₁. The data are grouped to a header part and an information part respectively by the parallel/serial switch 41, and parallel-inputted such that they are arranged in the same order as the cells inputted to the switch circuit. Then, data stored in the parallel/serial switch 41 are outputted sequentially in a bit synchronously with a clock signal, thus completing the output of all the whole ATM cells using 424 clocks. The header error control data (HEC) added to the parallel/serial switch shown in Figure 15 are outputted from the HEC operating unit 39 immediately after a data load (LOAD) signal shown in Figure 16 turns to 'H', but the timing is not indicated there. The HEC can be applied to the parallel/serial switch 41 without using the HEC operating unit 39 by storing in a flip flop the HEC as inputted to the serial-in/parallel-out shift register 31 as shown in Figure 11. However, as the process of the HEC is not related directly to the present invention, the explanation and illustration of the HEC operating unit is skipped hereafter. Figure 17 shows a block diagram of a configuration of an embodiment of the second principle. This embodiment comprises an ATM cell divider 45, an ATM cell switch 46, and an ATM cell output unit 47. The ATM cell divider 45 divides an ATM cell, except the HEC of an ATM cell, comprising a 32-bit header part and a 384 bit information part by e₁ (e₁ is a divisor of 32 other than 1 and 32) into e₁ (P₁, P₂, --- P e1 ) ATM primary sub-cells each having a n f₁ (f₁=32/e₁)-bit length header part H j (j=1-e₁) and a g₁ (g₁=384/e₁)-bit length information part K j (j=1-e₁), and then outputs these primary sub-cells from the output b j (j=1-e₁). The ATM primary sub-cell processor is provided with Z=2 fl outputs L₀, L₁, --- L y (Y=Z-1) for the inputs of ATM primary sub-cells, and allots the ATM sub-cells to any of the outputs L hj (L₀, L₁, --- L y ) according to the value h j of the header part H j of an ATM primary sub-cell. The ATM cell switch 46 comprises e₁ (Q₁, Q₂, --- Q e1 ) ATM primary sub-cell processors, and b j (j=1-e₁) is connected to each Q j (j=1-e₁) where an ATM primary sub-cell P j (j=1-e₁) is inputted. The ATM cell composer comprises e₁ f₁+g₁-bit ATM cell (each comprising an f₁-bit header part and g₁-bit information part) input units and assemblers for assembling ATM cells only when ATM primary sub-cells are inputted to all of ATM cell input units (R₁, R₂, --- R e1 ). The ATM cell output unit 47 comprises T (S₁, --- S T )(T: number of output lines) ATM cell composers, and an ATM cell having the header value (h₁, h₂, --- h e1 ) ) is outputted to the output C j in the ATM cell output unit by inputting the output L hj of the ATM primary sub-cell processor Q j (j=1-e₁) to the ATM cell input unit R j (j=1-e₁) according to the ATM sub-cell header value (h₁, h₂, --- h e1 ) expected by an output line. Figure 18 shows an example of an output signal of an ATM cell divider 45 in an embodiment of the second principle. In Figure 18, a 32-bit header part and a 384-bit information part of an ATM cell is divided by e₁, a divisor of 32 other than 1 and 32, into e₁ primary sub-cells each comprising a n f₁-bit header part and a g₁-bit information part. Figure 19 shows a block diagram for explaining a configuration of the ATM cell switch 46 and the ATM cell output unit 47in an embodiment according to the second principle. In Figure 19, the value of e₁ is assumed to be 8; the header part of a primary sub-cell comprises f₁=4 bits; and the information part comprises g₁=48 bits. Each of ATM primary sub-cell processors in the ATM cell switch 48 is provided with 2 f1 , that is, 16 output terminals. Primary sub-cells to be inputted to processors are outputted to any of 16 output terminals according to each item of header data. The number of ATM primary sub-cell processors is 8, and 8 input lines to each of ATM cell composers in the ATM cell output unit 49 are connected to the output terminals of the ATM primary sub-cell processors in the ATM cell switch 48 according to the header values corresponding to output lines. Figure 20 shows a circuit configuration of an ATM cell divider in an embodiment of the second principle; Figure 21 shows a time chart of the division of cells by the cell divider. The operation of the cell divider is explained in association with the operation of a cell divider in an embodiment of the first principle shown in Figures 11 and 12. In Figure 20, the cell divider comprises a switch 51 corresponding to the serial-in/parallel-out shift register 31 in Figure 11, e₁ switches 52₁, --- 52 e1 corresponding to the 32 parallel/serial switches 32₁, --- 32₃₂, and an inverter 53 corresponding to an inverter 33. The difference from Figure 11 is that an f₁-bit header part and a g₁-bit information part are parallel-inputted from the serial-in/parallel-out shift register 51 to each parallel/serial switch such that each of parallel/serial switches 51₁, --- 51 e2 outputs primary sub-cells. The last 1 bit is added to an outputted primary sub-cell to indicate the existence of a cell as in Figures 11 and 12. Therefore, the clock count for outputting primary sub-cells as shown in Figure 21 is equal to f₁+g₁+1. Figure 22 shows an example of a circuit configuration of a primary ATM sub-cell processor in the ATM cell dividor 46 shown in Figure 17. In this example, a configuration of a single-input multi-gate type circuit is shown as in Figures 3 and 4. The operation of this circuit is as described before, so the explanation is skipped here. Since there remains a problem with this circuit in that it is not always applicable to an LSI system, it is desirable to configure the primary sub-cell processors in a more hierarchical structure, which is described later as an embodiment of the third principle. Figure 23 shows a circuit configuration of an ATM cell composer in an embodiment of the second principle; Figure 24 shows a time chart for explaining the composition of cells by the cell composer. The operation of the composer is explained in comparison with the embodiment of the first principle shown in Figures 15 and 16. The cell composer in Figure 23, as in Figure 15, coprises e₁ cell input units 55₁, --- 55 e1 , a parallel/serial switch 56, AND gates 57 and 58, and an inverter 59. The difference from Figure 15 is that cells to be inputted to each of cell input units are primary sub-cells each comprising an f₁-bit header part, a g₁-bit information part, and a bit indicating the existence of a cell. Therefore, the clock count for inputting a primary sub-cell in Figure 24 is equal to f₁+g₁+1 compared with 14 in Figure 16. Figure 25 shows a configuration of an embodiment of a (q-1)th ATM sub-cell processorin an embodiment of the third principle. In Figure 25, if q=2, a detailed configuration without a multi-gate type circuit is used as an ATM cell switch system is shown in configuration of e₁ ATM primary sub-cell processors in the ATM cell switch 46 shown in Figure 17, which is defferent from Figure 22. The (q-1)th ATM sub-cell processor comprises a qth ATM sub-cell divider 60, a qth ATM sub-cell switch 61, and a qth ATM sub-cell output unit 62. The qth ATM sub-cell divider 60 divides a q-1th ATM sub-cell comprising an f q-1 (if q=2, f₁=32/e₁: e₁ is a divisor of 32 except 1 and 32)-bit header part and a g q-1 (g₁=384/e₁: e₁ is a divisor of 32 other than 1 and 32)-bit information part by e q (e q is a divisor of e q-1 other 1 and e q-1 ) into e q (P₁, P₂ ---P eq ) qth ATM sub-cells each comprising an f q (f q =f q- ₁/e q )-bit header part H j (j=1-e q ) and a g q (g q =g q- ₁/e₁)-bit information part Kj (j=1-e q ), and outputs each of qth sub-cells from any of the output terminals b j (j=1-e q ). The qth ATM sub-cell processor is provided with Z=2 fq outputs L₀, L₁ ... L y (Y=Z-1) for the inputs of qth ATM sub-cells, and allots the ATM sub-cells to the outputs L hj according to the values h j of the header part h j of qth ATM sub-cells. The qth ATM sub-cell switch 61 comprises e q qth ATM sub-cells processors (Q₁, Q₂, --- Q eq ), and b j (j=1-e q ) are connected to Q j (j=1-e q ) where qth ATM sub-cells P j are inputted. A qth ATM sub-cell composer comprises eq qth f q +g q -bit ATM sub-cell (R₁, R₂, --- R eq ) (each comprising an f q bit header part and a g q -bit information part) input units and assemblers for assembling q-lth ATM sub-cells only when qth ATM sub-cells are inputted to all of ATM cell input units (R₁, R₂, --- R eq ). The qth ATM sub-cell output unit 62 comprises T (S₁, --- S t )(T: the number of output lines of q-1th ATM sub-cell processors; that is, if q=2, the number of output lines of the primary ATM sub-cell processors shown in Figure 17 is equal to Y+1) qth ATM sub-cell composers. In each of qth ATM sub-cell composers S n (n=1-T), q-1th ATM sub-cells having the header value (h₁, h₂, ---, h eq ) can be outputted to the output C j of the qth ATM sub-cell output unit by inputting the output L hj of the qth ATM sub-cell processor Q j (j=1-e q ) to the qth ATM sub-cell input unit R j (j=1-e q ) according to the q-lth ATM sub-cell header value (h₁, h₂, --- h eq ) expected by an output line. In the configuration of the qth (q≧2) ATM sub-cell processors, sub-cell processors can be configured in a more hierarchical structure by increasing the value of q in Figure 25 without using a multi-step gate type circuit in a conventional ATM cell switch system. Figure 26 shows an embodiment of an output signal of the qth ATM sub-sell dividor 60 in the third principle shown in Figure 25. In Figure 26, a q-lth ATM sub-cell comprising an f q-1 -big header part and a g q-1 -bit information part is divided by e q , a divisor of e q-1 other than 1 and e q-1 , and e q of qth sub-cells each comprising an f q -bit header part and a g q -bit information part are outputted. Figure 27 shows a block diagram for explaining an example of a configuration of a secondary ATM sub-cell switch and a secondary ATM sub-cell output unit. Figure 27 refers to an example where e₁=8 and e₂=4. A primary sub-cell comprises a 4-bit header part and a 48-bit information part. A secondary sub-cell obtained by dividing a primary sub-cell by 4 comprises a 1-bit header part and a 12-bit information part, that is, unit cells. Accordingly, the configuration of the secondery ATM sub-cell switch 63 and the secondary ATM sub-cell output unit 64 is the same as that of the ATM cell switch 28 and the ATM cell output unit 29 shown in Figure 10 referred to as a configuration example of an embodiment of the first principle shown in Figure 8. Figure 28 shows a circuit configuration of a secondary ATM sub-cell divider in an embodiment of the third principle; Figure 29 shows a time chart for explaining the division of primary sub-cells by the above described divider. The secondary sub-cell divider forms a part of a primary sub-cell processor. In Figure 28, the secondary sub-cell divider comprises, like the divider shown in Figure 20 for dividing inputted ATM cells into primary sub-cells, a serial parallel switch 66 , a plurality of parallel/serial switches 67₁, --- 67₄ and an inverter 68. The difference from Figure 20 is that the cells inputted to the serial-in/parallel-out shift register 66 are primary sub-cells and a primary sub-cell comprising an f₁-bit header part (4 bits in this example) and a g₁-bit information part (48 bits in this example) are divided by 4 respectively and outputted as secondary ATM sub-cells, where a secondary ATM sub-cell comprises a 1-bit header part, referring to a unit cell. By contrast, in Figure 29, the clock count for the input of all the primary sub-cells is equal to f₁+g₁. One bit for indicating the existence of a cell is added by the ATM cell divider shown in Figure 20 to a primary sub-cell inputted as shown in Figure 28. As this one bit is added again to each of secondary sub-cells at the division of secondary sub-cells, it is not applied to the serial-in/parallel-out shift register 66. That is, a load signal turns to 'H' before this one bit is applied to the end of a primary sub-cell as shown in Figure 29. Figure 30 shows a circuit configuration of a secondary sub-cell processor; Figure 31 shows a time chart for explaining the switch of secondary sub-cells by the processor. As described above, secondary sub-cells are unit cells, and the circuit configuration shown in Figure 30 and the time chart shown in Figure 31 are the same as those of the first principle shown in Figures 13 and 14. Therefore, the explanation is skipped here. Figure 32 shows a circuit configuration of the secondary ATM sub-cell composer; Figure 33 shows a time chart of the assembly output of primary sub-cells by the composer. In Figure 32, the secondary sub-cell composer comprises a plurality of (4 in this example) cell input units 70₁, --- 70₄ parallel/serial switches 71, 2 AND gates 72 and 73, and an inverter 74. The difference from Figure 23 is that secondary sub-cells (unit cells in this example) are inputted in each of cell input units 70₁, --- 70₄, and a 1-bit header part and a 12-bit information part are outputted from each of cell input units to the parallel/serial switch 71 where primary sub-cells each comprising a 4-bit header part and a 48-bit information part are assembled and outputted. As shown in Figure 33, the clock count required for the input of secondary sub-cells to cell input units is a total of 14 clock; 1 for a header part, 12 for an information part, and 1 for 1 bit indicating the existence of a cell. The clock count required for the output of primary sub-cells is a total of 537; 4 for a header part, 48 for an information part, and 1 for a bit indicating the existence of a cell. Figure 34 shows a block diagram for explaining the configuration of an embodiment of the fourth principle. The fourth principle, to configure an ATM switch circuit in a multi-input type circuit using w input lines, complrises w (75₁, --- 75 W ) ATM cell dividers, e₁ (76₁, 76₂, --- 76 e1 ) multiplexers for multiplexing primary sub-cells located at the same relative position in an ATM cell to be outputted by ATM cell dividers, an ATM cell switch 77, and an ATM cell output units 78. w ATM cell dividers (A₁-A W ) divide an ATM cell, except the HEC, comprising a 32-bit header part and a 384-bit information part by e₁ (e₁ is a divisor of 32 except 1 and 32) into e₁ (P₁, P₂, --- P e1 ) primary ATM sub-cells each comprising an f₁(f₁=32/e₁-bit header part Hj (j=1-e₁) and a g₁ (g₁=384/e₁)-bit information part K j (j=1-e₁), and then outputs the primary sub-cells from the output b j (j=1-e₁). The multiplexer B j (j=1-e₁) multiplexes all the input complrising the output b j of the ATM cell divider (A₁-A W ), and outputs each of them it from the output line d j . A primary ATM sub-cell processor is provided with Z=2 f1 of outputs L₀, L₁, --- L y (Y=Z-1) for the input of the output d j of the multiplexer B j , and allots a primary ATM sub-cell to the output L hj according to the value h j of the header part H j of a primary ATM sub-cell. The ATM cell switch 77 comprises e₁ (Q₁, Q₂, ---Q e1 ) primary ATM sub-cell processors, and d j (j=1-e₁)is connected to Q j (j=1-e₁) where the primary ATM sub-cell P j (j=1-e₁) is inputted. An ATM cell composer comprises e₁ ATM cell input units and assemblers for assembling ATM cells only when primary ATM sub-cells are inputted to all of e₁ (R₁, R₂, --- R e1 ) ATM cell (a total of f₁+g₁ bits comprising an f₁-bit header part and a g₁-bit information part) input units. The ATM cell output unit 78 comprises T (S₁, ---S T ) (T: number of output lines) ATM cell composers. In each ATM cell composer S n (n=1-T), the ATM cell having the header value (h₁, h₂, ---, h e1 ) ) is outputted to the output C j of the ATM cell output unit by inputting the output L hj of the primary ATM sub-cell processor Q j (j=1-e) to the ATM cell input unit R j (j=1-e₁) according to the ATM sub-cell header value (h₁, h₂, ---, h e1 ) expected by an output line. Figure 35 shows a block diagram for explaining an embodiment of a multiplexer of the fourth principle. In Figure 35, a multiplexer, for example 76 j , comprises serial/parallel switches (S/P) 80₁, 80₂, ---, 80 W to which a jth primary sub-cell in an ATM cell is inputted, and a parallel/serial switch (P/S) 81 for converting the output of these serial/parallel switches to a serial signal. Figure 36 shows an example of an output signal of the ATM cell divider in an embodiment of the fourth principle. Figure 36 also shows an example of an input and output signals to the ATM cell divider 75k. An ATM cell (k) to be inputted to the ATM cell divider 75k is divided by e₁, a divisor of 32 other than 1 and 32, into e₁ primary sub-cells each comprising an f₁-bit header part and a g₁-bit information part. Figure 37 shows an embodiment of a signal of a multiplexer. In Figure 37, examples of a primary sub-cell inputted to the multiplexer 76j and the output of the multiplexer. An inputted primary sub-cell is a jth primary sub-cell P j (1) of an ATM cell (1), a jth primary sub-cell P j (2) of an ATM cell (2), and a jth primary sub-cell P j (w) of an ATM cell (w). These signals are multiplexed and outputted as serial signals. Figure 38 shows a circuit configuration of a multiplexer in an embodiment of the fourth principle; Figure 39 shows a time chart of multiplexing primary sub-cells by a multiplexer. In Figure 38, a multiplexer comprises, w serial/parallel switches 80₁, --- 80 W , a parallel/serial switch 81, as in Figure 35, and an inverter 82, not shown in Figure 35. Primary sub-cells located at the same relative position in an ATM cell and inputted through w input lines are inputted to each of serial/parallel switches. The primary sub-cell comprises an f₁-bit header part, a g₁-bit information part, and a last additional "1" bit indicating the existence of a cell. Therefore, the clock count required for the input of these primary sub-cell is equal to f₁+g₁+1 as shown in Figure 39. When all primary sub-cells are inputted, signals are parallel outputted from serial/parallel switches by applying load signals to the parallel/serial switch 81, and signals shown in Figure 37 are outputted from the parallel/serial switch 81. At this time, 1 bit is added, for indicating the existence of a cell. This is the last bit of a primary sub-cell in a multiplexing signal. According to the above described explanation, an ATM cell comprises a 32-bit header part and a 384-bit information part, excluding the header error control data. However, it is obvious that the present invention can is applicable when the number of header bits and the number of information bits excluding the header error control data have a common divisor, and the number of bits is not limited to specific values. As described above, in the present invention, an ATM switch circuit can be formed in a hierarchical structure comprising an ATM cell divider, an ATM cell switch, and an ATM cell output unit. Besides, additional ATM cell composers and necessary wiring between an additional ATM cell composer and an ATM cell switch permit more of output lines and a switch circuit applicable to an LSI system. Furthermore, an ATM cell switch can be configured in a small number of modules using units of primary ATM sub-cell processors. A primary ATM sub-cell processor can comprise a secondary ATM sub-cell divider, a secondary ATM sub-cell switch, and a secondary ATM sub-cell output unit, and secondary ATM sub-cell processors for forming a secondary ATM sub-cell switch can be configured likewise in a hierarchical structure, thus realizing more hierarchical processing. Furthermore, a multi-input type switch circuit can be formed by adding multiplexers to the above described hierarchical ATM switch circuit, thus realizing a circuit, applicable to an LSI system, comprising a plurality of ATM cell dividers and multiplexers corresponding to a plurality of input lines, an ATM cell switch, and an ATM cell output unit. Therefore, the present invention serves for realizing a variety of system configurations and reduction of the amount of work required for system modification. The present invention is applied to an ATM cell switch where the number of header bits as destination data of an ATM cell and the number of information bits excluding header error control data have a common divisor, and can be useful for various communication networks such as a broadband ISDN, and multi-media networks of voice, data, images, etc.

Claims: An asynchronous transmission mode (ATM) switch circuit configuration system comprising: an ATM cell dividing means (10) for dividing an ATM cell comprising header part data and information part data except header error control data respectively by the number of data bits of said header into a plurality of unit cells comprising a 1-bit header part and a divided information part, and for outputting said unit cells from the equal number of output terminals as the divisor; a unit cell switching means (11) comprising input terminals corresponding to a plurality of output terminals of said ATM cell dividing means for outputting unit cells inputted by said ATM cell dividing means to either of two output terminals corresponding to each of said input terminals according to the value of header data of said unit cell; and a plurality of ATM cell assembly output means (12₁...12 t ) provided for each of t output lines of said ATM switch circuit; said output means comprising input terminals where half the outputs of a plurality of output terminals of said unit cell switching means are inputted according to each header value of an ATM cell to be outputted, wherein all of unit cells are assembled and outputted as an ATM cell when unit cells are inputted from said unit cell switching means to all of input terminals. An ATM switch circuit configuration system according to Claim 1, wherein an ATM cell divider forming said ATM cell dividing means comprises; a serial-in/parallel-out shift register for parallel-outputting inputted data except header error control data after all of header parts and information parts including header said HEC are serial-inputted bit by bit synchronously with a clock signal, and a plurality of parallel/serial switches for serial-outputting a 1-bit header part, a divided information part, and additional 1-bit data for indicating the existence of cell data in this order synchronously with a clock signal after they are parallel-inputted as output of said serial-in/parallel-out shift register. An ATM switch circuit configuration system according to Claim 2, wherein an ATM cell assembler forming said ATM cell assembly output means comprises; a plurality of cell input units comprising a plurality of serial/parallel switches connected to input terminals (the number of which corresponds to half number of output terminals of said unit cell switching means) where unit cells each comprising a header part, an information part, and additional 1-bit data indicating the existence of cell data are serial-inputted synchronously with a clock signal, and then parallel-outputted, and a cell assembler comprising an AND gate where all 1-bit data indicating the existence of cell data in the output of each of said serial/parallel switches are inputted; and a parallel/serial switch where header parts and information parts of unit cells in the output of each of said serial/parallel switches are combined respectively, parallel-loaded when said AND gate outputs "1", in the same order of data when a cell is inputted to said ATM switch circuit, and then serial-outputted synchronously with a clock signal. An ATM switch circuit configuration system according to Claim 1, wherein an ATM cell switch forming said unit cell switching means comprises; a plurality of ATM unit cell processors where said ATM unit cells are inputted, each of said ATM unit cell processor comprising a single-input and double-output selector for switching inputted ATM unit cells, a first D flip flop for outputting, according to said 1-bit data in said unit cell, a selection control signal to said selector when said 1-bit data is inputted, and a second D flip flop for outputting inputted unit cell data "as is" to said selector synchronously with a clock signal. An ATM switch circuit system comprising; a primary sub-cell dividing means (13) for dividing a header part and an information part of an ATM cell except header error control data respectively by a divisor e₁ smaller than the number of header bits of said header part into e₁ (e₁≧2) primary ATM sub-cells each comprising an f₁ (data length of the header part/e₁)-bit header part and a g₁ (data length of the information part/e₁ )-bit information part, and outputting said primary sub-cells from e₁ output terminals, a primary sub-cell switching means (14) comprising e₁ input terminals corresponding to e₁ output terminals of said primary sub-cell dividing means, and comprising 2 f1 x e₁ output terminals where sub-cells inputted by said primary sub-cell dividing means to said e₁ input terminals are outputted, according to the header part data value of said primary sub-cell, from any of 2 f1 output terminals corresponding to input terminals, and a plurality (t) of ATM cell assembly output means (15₁... 15 t ) comprising e₁ input terminals provided corresponding to the number of output lines t in the ATM switch circuit where e₁ outputs in 2 f1 x e₁ output terminals in said primary sub-cell switch means are inputted according to the header data value of an ATM cell to be outputted to said output line, wherein e₁ primary sub-cells are assembled and outputted as an ATM cell when primary sub-cells are inputted by said primary sub-cell switching means to all of said e₁ input terminals. An ATM switch circuit configuration system according to Claim 5, wherein an ATM cell divider forming said sub-cell dividing means comprises; a serial-in/parallel-out shift register where a header part, an information part, including said HEC are serial-inputted bit by bit synchronously with a clock signal, and then parallel-outputted except header error control data (HEC) after the header part and information part are input, and e₁ parallel/serial switches where an f₁-bit header part, a g₁-bit divided information part, and 1-bit data indicating the existence of cell data are parallel-inputted as output of said serial-in/parallel-out shift register and then serial-outputted synchronously with a clock signal in the same order when they are inputted. An ATM switch circuit configuration system according to Claim 6, wherein an ATM cell assembler forming said ATM cell assembly output means comprises; e₁ cell input units comprising e₁ serial/parallel switches, connected to said e₁ input terminals, where primary sub-cells comprising an f₁-bit header part, a g₁-bit information part, and 1-bit data indicating the existence of said cell data are serial-inputted synchronously with a clock signal from said input terminal, and then parallel-outputted after completion of the input, and a cell assembler comprising a an AND gate where all additional 1-bit data indicating the existence of cell data in the output of each of said serial/parallel switches are inputted; and a parallel/serial switch where header parts and information parts in the output of each of said serial/parallel switches are combined respectively, parallel-loaded in the same order of data when a cell is inputted to said ATM switch circuit, when said AND gate outputs "1", and then the loaded result is serial-outputted synchronously with a clock signal. An ATM switch circuit configuration system according to Claim 5, wherein said primary sub-cell switching means comprises e₁ primary sub-cell processing means where signals from e₁ output terminals of said primary sub-cell dividing means are inputted and primary sub-cells inputted by said primary sub-cell dividing means are outputted to one of 2 f1 output terminals according to the header data value of a primary sub-cell, said primary sub-cell processing means comprises a secondary sub-cell dividing means for dividing a fl-bit header part and a g₁-bit information part of said primary sub-cell respectively by e₂, a divisor of e₁ except 1 and e₁ into e₂ secondary sub-cells each comprising an f₂ (f₂=f₁/e₁)-bit header part and a g₂ (g₂=g₁/e₁)-bit information part, and for outputting secondary sub-cells from e₂ output terminals; a secondary sub-cell switching means comprising e₂ secondary sub-cell processing means where secondary sub-cells outputted by said secondary sub-cell dividing means are inputted, and said secondary sub-cells are outputted to one of 2 f2 output terminals according to the header data value of said secondary sub-cell; and a secondary sub-cell assembly output means provided corresponding to the number t₂ (t₂=2 f1 ) of said 2 f1 output terminals, said recondary sub-cell assembly output means comprising e₂ input terminals where e₂ outputs in 2 f2 x e₂ output terminals of said secondary sub-cell switching means are inputted according to the header value of a primary sub-cell to be outputted to said output terminal, wherein said e₂ secondary sub-cells are assembled and outputted as a primary sub-cell to said ATM cell assembly output means when secondary sub-cells are inputted to all of said e₂ input terminals from said secondary sub-cell switch means, and in general a (q-1)th (q≥3) sub-cell processing means comprises a qth sub-cell dividing means for dividing an f q-1 -bit header part and a g q-1 -bit information part of a (q-1)th sub-cell by e q , a divisor of e q except 1 and e q-1 into e q (q-1)th sub-cells each comprising an f q (f q =f g-1 /e q )-bit header part and a g q (g q =g q-1 /e q )-bit information part and outputting these qth sub-cells from e q output terminals; a qth sub-cell switching means comprising e q qth sub-cell processing means where qth sub-cells outputted from said qth sub-cell dividing means are inputted and outputted from any of 2 fq output terminal according to the head data value of said qth sub-cell; a qth sub-cell assembly output means comprising e q input terminals provided corresponding to 2 q-1 output lines of the (q-1)th sub-cell processing means where e q outputs in 2 fq x e q output terminals of said qth sub-cell switching means are inputted according to the header value of the (q-1)th sub-cell to be outputted to said output line, wherein said e q qth sub-cells are assembled and outputted as a (q-1)th sub-cell when qth sub-cells are inputted from said qth sub-cell switching means to all of said e q input terminals; wherein a qth sub-cell processing means are configured in a hierarchical structure with the increase of the value q. An ATM switch circuit configuration system according to Claim 8, wherein a secondary ATM sub-cell divider forming said secondary sub-cell dividing means comprises; a serial-in/parallel-out shift register where an f₁-bit header part and a g₁-bit information part of a primary ATM sub-cell are serial-inputted bit by bit synchronously with a clock signal and then parallel-outputted after all of said header part and information part are inputted, and e₂ parallel/serial switches where data containing an f₂ (f₂=f₁/e₂)-bit header part, a g₂ (g₂=g₁/e₂)-bit information part, and an additional 1-bit indicating the existence of cell data are parallel-inputted as an output of said serial-in/parallel-out shift register and then serial-outputted synchronously with a clock signal in the order they are inputted . An ATM switch circuit configuration system according to Claim 9, wherein an ATM secondary sub-cell assembler forming said secondary sub-cell assembly output means comprises; e₂ cell input units comprising e₂ serial/parallel switches connected to said e₂ input terminals where an f₂-bit header part, a g₂-bit information part, and additional 1-bit indicating the existence of cell data are serial-inputted from each input terminal synchronously with a clock signal and then parallel-outputted, and a cell assembler comprising an AND gate where all additional 1-bit data indicating the existence of cell data in the output of each of said serial/parallel switches are inputted; and a parallel/serial switch where header parts and information parts in the output of each of said serial/parallel switches are combined respectively, parallel-loaded when said AND gate outputs "1", in the same order of data as in a primary ATM sub-cell, and then serial-outputted synchronously with a clock signal. An ATM switch circuit configuration system comprising; a plurality of primary sub-cell dividing means (21₁...21 W ), each provided corresponding to each input line, for dividing a header part and an information part of an ATM cell inputted from a plurality (w) of input lines except header error control data by e₁, a divisor smaller than the number of data bits in said header part into e₁ (e₁≧2) primary sub-cells each comprising an f₁ (number of header data bits/e₁)-bit header part and a g₁ (number of information data bits/e₁)-bit information part, and outputting primary sub-cell from e₁ output terminals, e₁ primary sub-cell multiplexing means (22₁...22 e1 ) for multiplexing primary sub-cells at the same relative position in an ATM cell outputted by a plurality of said primary sub-cell dividing means and inputted from a plurality of said input lines, a primary sub-cell switching means (23) comprising e₁ input lines corresponding to the number of said primary sub-cell multiplexing means, wherein primary sub-cells inputted from said primary sub-cell multiplexing means to said e₁ input terminals are outputted according to the header data value of said primary sub-cell to any of 2 f1 output terminals corresponding to input terminals, and an ATM cell assembly output means (24...24 t ) comprising e₁ input terminals provided corresponding to the number t of output lines of said ATM switch circuit where e₁ outputs in 2 f1 x e₁ output terminals of said primary sub-cell switching means are outputted according to the header data value of an ATM cell outputted to said output line, wherein e₁ primary sub-cells are assembled and outputted as an ATM cell when primary sub-cells are inputted from said primary sub-cell switching means to all of e₁ input terminals. An ATM switch circuit configuration system according to Claim 11, wherein an ATM cell divider forming said primary sub-cell dividing means comprises; a serial-in/parallel-out shift register where a header part and an information part including header error control data (HEC) of an ATM cell are serial-inputted bit by bit synchronously with a clock signal and parallel-outputted excluding said HEC after said header part and information part are inputted, and e₁ parallel/serial switches where an f₁-bit header part, a divided g₁-bit information part, and 1-bit data indicating the existence of cell data are parallel-inputted as output of said serial-in/parallel-out shift register and serial-outputted synchronously with a clock signal in the order they are inputted. An ATM switch circuit configuration system according to Claim 12, wherein an ATM cell assembler forming said ATM cell assembly output means comprises; e₁ cell input units comprising e₁ serial/parallel switches, connected to said e₁ input terminals, where primary sub-cells comprising an f₁-bit header part, a g₁-bit information part, and 1-bit data indicating the existence of said cell data are serial-inputted synchronously with a clock signal from said input terminal, and then parallel-outputted after completion of the input, and a cell assembler comprising an AND gate where all additional 1-bit data indicating the existence of cell data in the output of each of said serial/parallel switches are inputted; and a parallel/serial switch where header parts and information parts in the output of each of said serial/parallel switches are combined respectively, parallel-loaded when said AND gate outputs "1", in the same order of data when a cell is inputted to said ATM switch circuit, and then serial-outputted synchronously with a clock signal. An ATM switch circuit configuration system according to Claim 11, wherein said primary sub-cell switching means comprises e₁ primary sub-cell processing means where signals from e₁ output terminals of said primary sub-cell dividing means are inputted and primary sub-cells inputted by said primary sub-cell dividing means are outputted to any of 2 f1 output terminals according to the header data value of a primary sub-cell, said primary sub-cell processing means comprises a secondary sub-cell dividing means for dividing a f₁-bit header part and a g₁-bit information part of said primary sub-cell respectively by e₂, a divisor of e₁ except 1 and e₁ into e₂ secondary sub-cells each comprising an f₂ (f₂=f₁/e₁)-bit header part and a g₂ (g₂=g₁/e₁)-bit information part, and for outputting secondary sub-cells from e₂ output terminals; a secondary sub-cell switching means comprising e₂ secondary sub-cell processing means where secondary sub-cells outputted by said secondary sub-cell dividing means are inputted, and said secondary sub-cells are outputted to any of 2 f2 output terminals according to the header data value of said secondary sub-cell; and a secondary sub-cell assembly output means provided corresponding to the number t₂ (t₂=2 f1 ) of said 2 f1 output terminals, said secondary sub-cell assembly output means comprising e₂ input terminals where e₂ outputs in 2 f2 x e₂ output terminals of said secondary sub-cell switching means are inputted according to the header value of a primary sub-cell to be outputted to said output terminal, wherein said e₂ secondary sub-cells are assembled and outputted as a primary sub-cell to said ATM cell assembly output means when secondary sub-cells are inputted to all of said e₂ input terminals from said secondary sub-cell switch means, and in general a (q-1)th (q≧3) sub-cell processing means comprises a qth sub-cell dividing means for dividing an f q-1 -bit header part and a g q-1 -big information part of a (q-1)th sub-cell by e q , a divisor except 1 and e q-1 into e q (q-1)th sub-cells each comprising an f q (f q =f q-1 /e q )-bit header part and a g q (g q =g q-1 /e q )-bit information part and outputting these qth sub-cells from e q output terminals; a qth sub-cell switching means comprising e q qth sub-cell processing means where qth sub-cells outputted from said qth sub-cell dividing means are inputted and outputted from any of 2 fq output terminal according to the head data value of said qth sub-cell; a qth sub-cell assembly output means comprising e q input terminals provided corresponding to 2 q-1 output lines of the (q-1 )th sub-cell processing means where e q outputs in 2 fq x e q output terminals of said qth sub-cell switching means are inputted according to the header value of the (q1)th sub-cell to be outputted to said output line, wherein said e q qth sub-cells are assembled and outputted as a (q-1)th sub-cell when qth sub-cells are inputted from said qth sub-cell switching means to all of said e q input terminals; wherein a qth sub-cell processing means are configured in a hierarchical structure with the increase of the value q. An ATM switch circuit configuration system according to Claim 11, wherein a multiplexer forming said primary sub-cell multiplexing means comprises; w serial/parallel switches provided corresponding to w of said input lines where a primary sub-cell comprising an f₁-bit header part, a g₁-bit information part, and a 1-bit data indicating the existence of cell data each located at the same relative position in an ATM cell are serial-inputted synchronously with a clock signal bit by bit, and then parallel-outputted, and a parallel/serial switch where output of each of said serial/parallel switches is parallel-inputted collectively and then serial-outputted synchronously with a clock signal . An asynchronous transmission mode (ATM) switch circuit configuration system, comprising an ATM cell dividing means for dividing an ATM cell comprising header part data and information part data into either a plurality of unit cells each having a 1-bit header part and a divided information part or into a plurality of sub-cells having a multi-bit header part and a divived information part; a divided cell switching means for switching and outputting to a corresponding output line said unit cells or sub-cells according to the value of the header part of said unit cell or sub-cell, respectively; and an ATM cell output unit for assembling, from said switched unit cell or sub-cell, an ATM cell comprising a header part corresponding to the number of output lines of said divided cell switching means, and for outputting the assembled ATM cell.

Inventors: NAKAYAMA MIKIO, NAKAYAMA, MIKIO
Applicants: FUJITSU LTD, FUJITSU LIMITED
Application year: 1991
Main classification: H04L12
IPC codes: H04L12, H04Q3