Selective cell discard system in atm switch

Abstract

Disclosed is a selective cell discard system in an ATM switch to transfer exchanging a cell input from a plurality of input ports to a plurality of output ports, for controlling the selective cell discard to guarantee QOS (quality of service) by controlling the order of cell discard or the read-out order of cells accumulated in cell buffer when a plenty of cells exceeding the exchange capability of the switch is input, the system having: a selective cell discard controller connected to each of the plurality of input ports; a first-stage switch unit comprising all of cell buffers for output port group provided corresponding to output port groups into which the plurality of output ports are divided, and a cell multiplexer which inputs exchanging all of cells to be input from the plurality of input ports through the selective cell discard controller according to routing information of concerned cells; a groups of second-stage switch units which are provided corresponding to each of the cell buffers for output port group and input exchanging a cell in a concerned cell buffer for output port group to any of cell buffers for output port provided corresponding to output ports belonging to a concerned output port group; and means for detecting a congestion in the cell buffer for output port group, and discard-controlling a cell to be input to the concerned cell buffer for output port group in the selective cell discard controller.