Patent ID: 6907001

Claim:
A packet switch connected to a plurality of input lines and output lines for forwarding variable length packets received from each of said input lines to one of said output lines specified by respective header information, said packet switch comprising: a switch unit, having a plurality of input ports and output ports corresponding to said input lines and output lines, respectively, which outputs fixed length cells received from each of said input ports to one of said output ports specified by routing information contained in the cell header of said received cells; a plurality of input line interfaces, each connected to one of said input ports, which convert the variable length packets received from one of said input lines to fixed length cells and supply the fixed length cells to the one input port; and a plurality of output line interfaces, each connected to one of said output ports which convert output cells received from the one output port to variable length packets and send out the packets to one of said output lines, wherein each of said input line interfaces has a cell output controller which stores the cells converted from said variable length packets in queues formed for each output line according to a degree of priority of respective cells and selectively forwards the stored cells to said input port according to the degree of priority of the respective cells, wherein each output line interface comprises: a cell disassembler unit which receives the output cells from one of said output ports and delivers data blocks obtained by removing a cell header from each of said output cells, a buffer memory connected to said cell disassembler unit, a memory controller which stores said data blocks delivered from said disassembler into said buffer memory according to identification information contained in said cell header, and a buffer monitor coupled with said memory controller so as to monitor the data blocks stored in said buffer memory and issue a notice of congestion indicating the cell congestion status, and wherein the cell output controller in each of said input line interfaces selectively prohibits the forwarding of cells according to the degree of priority of the respective cells as to the output lines specified by the notice of congestion.