Patent ID: 6122252
Filing Date: 2000-09-19
Classification: H04L

Abstract:
A cell switching system for controlling transfer of ATM (Asynchronous Transfer Mode) cells wherein each cell has a header portion and a data portion with a message, comprising:a plurality of input line interfaces for receiving cells from lines;a plurality of output line interfaces for outputting cells to lines;a plurality of output buffers corresponding to the respective output lines, each of the output buffers having a first counter counting the number of cells held therein and a second counter counting the number of cells held therein for each connection;a switch connected to the input line interfaces and the output buffers, for switching cells from the input line interfaces to any of the buffers; anda congestion state judgment unit connected to the buffers and the input line interfaces, for judging congestion state of the output buffers based on values from the first counters;wherein each of input line interfaces includes a cell discard judgment unit connected to each of the second counters and the congestion state judgment unit, for judging whether to discard inputted cells or not for each connection by comparing values from the second counters with a cell discard threshold information for each connection, and changing the cell discard threshold information based on the congestion state from the congestion state judgment unit; andwherein each of the input line interfaces selectively discards inputted cells without transmitting the cells to the switch for each connection based on the judgment of the cell discard judgement unit.