Cell switching apparatus and method

Claim 2

An asynchronous transfer mode (ATM) cell exchanging apparatus for distributing input cells to corresponding cell output lines, each input cell including a data portion and a header portion having address information, comprising: a) a first cell switch for distributing the input cells, to a first set of switch output lines in accordance with the address information of the header portions of the input cells, said first cell switch outputting an idle cell when there are no input cells; b) a second redundant cell switch for dis - tributing the input cells to a second set of switch output lines in accordance with the address information of the header portions of the input cells, said second cell switch outputting an idle cell when there are no input cells; and c) a selection mechanism for selecting which of the first set of switch output lines and the second set of switch output lines is a currently selected and spare set of switch output lines that provides cells to the cell output lines, wherein said selection mechanism is switchable between selecting the first set of switch output lines and the second set of switch output lines, said se - lection mechanism including: a confirmation mechanism for confirm - ing that idle cells are output on each of output lines in the currently selected set of switch output lines before switching selection by the selection mechanism from the currently selected set of switch output lines to the other set of switch output lines.

Claim 3

A cell exchanging apparatus as recited in claim 1 wherein the first cell switch comprises several unit switches.

Claim 4

A cell exchanging apparatus as recited in claim 1 wherein the second cell switch comprises several unit switches.

Claim 5

A cell exchanging apparatus as recited in claim 1, further comprising arbitration logic for arbitrating competing requests to output a cell over a same switch output line.

Claim 6

In an asynchronous transfer mode (ATM) cell exchanging apparatus, having cell output lines, a first cell switch with first switch output lines, which generates idle cells when no cells are input, a second cell switch with second switch output lines, which generates idle cells when no cells are input, and a selection mechanism for selecting which of the first switch output lines and the second switch output lines is selected to provide cells to the cell output lines, a method, comprising the steps of: a) providing an initial selection that selects the first set of switch output lines to provide cells to the cell output lines; b) generating a change-over signal to the selection mechanism; c) confirming that idle cells are present on each of the first switch output lines; and d) using the selection mechanism in response to the control signal so that the second switch output lines provide cells to the cell output lines.

Claim 7

In an asynchronous transfer mode (ATM) cell exchanging apparatus, having cell output lines, a first cell switch with first switch output lines, which generates idle cells when no cells are input, a second cell switch with second switch output lines, which generates idle cells when no cells are input, and a selection mechanism for selecting which of the first switch output lines and the second switch output lines is selected to provide cells to the cell output lines, a method, comprising the steps of: a) providing an initial selection that selects the first set of switch output lines to provide cells to the cell output lines; b) generating a change-over signal to the selection mechanism; c) confirming that idle cells are present on each of the first switch output lines; and d) using the selection mechanism in response to the control signal so that the second switch output lines provide cells to the cell output lines.

Claim 8

An asynchronous transfer mode (ATM) cell exchanging apparatus for distributing input cells to corresponding cell output lines, each input cell including a data portion and a header portion having address information, comprising: a) a first cell switch for distributing the input cells to a first set of switch output lines in accordance with the address information of the header portion of the input cells, said first cell switch comprising: i) a plurality of unit switches, wherein each of the unit switches output cells that are input from input terminals to select switch output lines in the first set of switch output lines in accordance with address information provided in the input cells, each of the unit switches being provided with buffers to temporarily store cells to be output, and each of the unit switches requesting permission to output a cell when a cell is stored in the output buffer of the unit switch; and ii) an arbitration circuit for granting permission to one of the unit switches, which are connected to a same output line and which are requesting permission to output a cell to that output line, so that only the cell in the unit switch which is granted permission by the arbitration circuit is output to the switch output line, and said arbitration circuit instructing one of the unit switches to output an idle cell when no unit switch means requests permission to output a cell; b) a second redundant cell switch for dis - tributing the input cells to a second set of switch output lines in accordance with the address information of the header portions of the input cells, said second cell switch comprising: i) a plurality of unit switches, wherein each of the unit switches output cells that are input from input terminals to select switch output lines in the second set of switch output lines in accordance with address information provided in the input cells, each of the unit switches being provided with buffers to temporarily store cells to be output, and each of the unit switches requesting permission to output a cell when a cell is stored in the buffer of the unit switch; and ii) an arbitration circuit for granting permission to one of the unit switches which are connected to a same output line and, which are requesting permission to output a cell to that output line, so that only the cell in the unit switch which is granted permission by the arbitration circuit is output to the switch output line, and said arbitration circuit instructing one of the unit switches to output an idle cell when no unit switch means requests permission to output a cell; c) a selection mechanism for selecting which of the first set and the second set of switch output lines is a currently selected set of switch output lines that provides cells to the cell output lines, wherein said selec - tion mechanism is switchable between selecting the first set and the second set of switch output lines, respectively, said selection mechanism including: i) a confirmation mechanism for con - firming that idle cells are output on each of the currently selected and spare set of switch output lines before switching se - lection by the selection mechanism of cells from the currently selected set and spare set of switch output lines to the other set of switch output lines.

Claim 9

An asynchronous transfer mode (ATM) cell exchanging apparatus for distributing input cells to corresponding cell output lines, each input cell including a data portion and a header portion having address information, comprising: a) a first cell switch for distributing the input cells to a first set of switch output lines in accordance with the address information of the header portion of the input cells, said first cell switch comprising: i) a plurality of unit switches, wherein each of the unit switches output cells that are input from input terminals to select switch output lines in the first set of switch output lines in accordance with address information provided in the input cells, each of the unit switches being provided with buffers to temporarily store cells to be output, and each of the unit switches requesting permission to output a cell when a cell is stored in the output buffer of the unit switch; and ii) an arbitration circuit for granting permission to one of the unit switches, which are connected to a same output line and which are requesting permission to output a cell to that output line, so that only the cell in the unit switch which is granted permission by the arbitration circuit is output to the switch output line, and said arbitration circuit instructing one of the unit switches to output an idle cell when no unit switch means requests permission to output a cell; b) a second redundant cell switch for dis - tributing the input cells to a second set of switch output lines in accordance with the address information of the header portions of the input cells, said second cell switch comprising: i) a plurality of unit switches, wherein each of the unit switches output cells that are input from input terminals to select switch output lines in the second set of switch output lines in accordance with address information provided in the input cells, each of the unit switches being provided with buffers to temporarily store cells to be output, and each of the unit switches requesting permission to output a cell when a cell is stored in the buffer of the unit switch; and ii) an arbitration circuit for granting permission to one of the unit switches which are connected to a same output line and, which are requesting permission to output a cell to that output line, so that only the cell in the unit switch which is granted permission by the arbitration circuit is output to the switch output line, and said arbitration circuit instructing one of the unit switches to output an idle cell when no unit switch means requests permission to output a cell; c) a selection mechanism for selecting which of the first set and the second set of switch output lines is a currently selected set of switch output lines that provides cells to the cell output lines, wherein said selec - tion mechanism is switchable between selecting the first set and the second set of switch output lines, respectively, said selection mechanism including: i) a confirmation mechanism for con - firming that idle cells are output on each of the currently selected and spare set of switch output lines before switching se - lection by the selection mechanism of cells from the currently selected set and spare set of switch output lines to the other set of switch output lines.

Claim 10

An asynchronous transfer mode (ATM) cell exchanging apparatus for distributing input cells to corresponding cell output lines, each input cell including a data portion and a header portion having address information, compris - ing: a) a first cell switch for distributing the input cells to a first set of switch output lines in accordance with the address information of the header portion of the input cells, said first cell switch comprising: i) a plurality of unit switches, wherein each of the unit switches output cells that are input from input terminals to select switch output lines in the first set of switch output lines in accordance with address information provided in the input cells, each of the unit switches being provided with output buffers to temporarily store cells to be output, and each of the unit switches requesting permission to output a cell when a cell is stored in the output buffer of the unit switch; and ii) an arbitration circuit for granting permission to one of the unit switches, which are connected to a same output line and which are requesting permission to output a cell to that output line, so that only the cell in the unit switch which is granted permission by the arbitration circuit is output to the switch output line, and said arbitration circuit instructing one of the unit switches to output an idle cell when no unit switch means requests permission to output a cell; b) a second redundant cell switch for dis - tributing the input cells to a second set of switch output lines in accordance with the address information of the header portions of the input cells, said second cell switch comprising: i) a plurality of unit switches, wherein each of the unit switches output cells that are input from input terminals to select switch output lines in the second set of switch output lines in accordance with address information provided in the input cells, the unit switches being provided with common output buffers for them - selves to temporarily store cells to be output, and each of the unit switches requesting permission to output a cell when a cell is stored in the output buffer of the unit switch; and ii) an arbitration circuit for granting permission to one of the unit switches which are connected to a same output line and, which are requesting permission to output a cell to that output line, so that only the cell in the unit switch which is granted permission by the arbitration circuit is output to the switch output line, and said arbitration circuit instructing one of the unit switches to output an idle cell when no unit switch means requests permission to output a cell; c) a selection mechanism for selecting which of the first set and the second set of switch output lines is a currently selected set of switch output lines that provides cells to the cell output lines, wherein said selec - tion mechanism is switchable between selecting the first set and the second set of switch output lines, respectively, said selection mechanism including: i) a confirmation mechanism for con - firming that idle cells are output on each of the currently selected and spare set of switch output lines before switching se - lection by the selection mechanism of cells from the currently selected set and spare set of switch output lines to the other set of switch output lines.

Claim 11

An asynchronous transfer mode (ATM) cell exchanging apparatus for distributing input cells to corresponding cell output lines, each input cell including a data portion and a header portion having address information, compris - ing: a) a first cell switch for distributing the input cells to a first set of switch output lines in accordance with the address information of the header portion of the input cells, said first cell switch comprising: i) a plurality of unit switches, wherein each of the unit switches output cells that are input from input terminals to select switch output lines in the first set of switch output lines in accordance with address information provided in the input cells, each of the unit switches being provided with output buffers to temporarily store cells to be output, and each of the unit switches requesting permission to output a cell when a cell is stored in the output buffer of the unit switch; and ii) an arbitration circuit for granting permission to one of the unit switches, which are connected to a same output line and which are requesting permission to output a cell to that output line, so that only the cell in the unit switch which is granted permission by the arbitration circuit is output to the switch output line, and said arbitration circuit instructing one of the unit switches to output an idle cell when no unit switch means requests permission to output a cell; b) a second redundant cell switch for dis - tributing the input cells to a second set of switch output lines in accordance with the address information of the header portions of the input cells, said second cell switch comprising: i) a plurality of unit switches, wherein each of the unit switches output cells that are input from input terminals to select switch output lines in the second set of switch output lines in accordance with address information provided in the input cells, the unit switches being provided with common output buffers for them - selves to temporarily store cells to be output, and each of the unit switches requesting permission to output a cell when a cell is stored in the output buffer of the unit switch; and ii) an arbitration circuit for granting permission to one of the unit switches which are connected to a same output line and, which are requesting permission to output a cell to that output line, so that only the cell in the unit switch which is granted permission by the arbitration circuit is output to the switch output line, and said arbitration circuit instructing one of the unit switches to output an idle cell when no unit switch means requests permission to output a cell; c) a selection mechanism for selecting which of the first set and the second set of switch output lines is a currently selected set of switch output lines that provides cells to the cell output lines, wherein said selec - tion mechanism is switchable between selecting the first set and the second set of switch output lines, respectively, said selection mechanism including: i) a confirmation mechanism for con - firming that idle cells are output on each of the currently selected and spare set of switch output lines before switching se - lection by the selection mechanism of cells from the currently selected set and spare set of switch output lines to the other set of switch output lines.