Patent ID: 7136391

Claim:
An ATM switch comprising: at least one basic switch, said basic switch including means for referring to time information written in a header of an input cell and for switching cells to an output port in an ascending order of said time information, said means including: plural cross-points, wherein at each of the cross-points an input line and an output line are crossed, and wherein the plural cross-points are layered, each cross-point including: an address filter for extracting a cell arriving from the input line; a first buffer which stores the extracted cell; a second buffer which stores a cell arriving from another cross-point; and means for comparing time information of a head cell in said first buffer with time information of a head cell in said second buffer and for sending a head cell with earlier time information to the another cross-point or said output port; wherein said address filter captures a cell having an address of said address filter as an active cell which includes user data, and generates, for a cell that does not have said address of said address filter, a dummy cell, which does not include user data, with time information of the cell, and stores said active cell or said dummy cell in said first buffer, if types of head cells in said first buffer and said second buffer are the same and also time information of said head cells are the same, a k-th cross point selects a head cell from said first buffer and said second buffer with a probability of a ratio of 1 to k−1 so as to send a selected head cell to the another cross-point or said output port, wherein k is a natural number, and if said types of head cells are different but time information are the same, said address filter selects said active cell so as to send said active cell to other cross-point or said output port.