Distributed buffering system for ATM switches

Claim 1

An ATM switch for transferring cells from a plurality of input channels to a plurality of output channels, said switch comprising a plurality of input ports, each input port connected to one of said input channels and receiving cells from said one input channel, said input port having an input buffer holding cells when said cells arrive faster from said input channel than said input port transmits; a plurality of output ports, each output port connected to one of said output channels and transmitting cells to said one output channel, said output port having an output buffer holding cells when said cells arrive faster from said input ports than said output port transmits; a switch block connected between each one of said input ports and each one of said output ports, said switch block conveying cells from said input ports to said output ports, said switch block having a plurality of interconnected switch elements, each switch element having a plurality of input terminals, a plurality of output terminals and a switch bus, each input terminal having an input buffer holding cells received by said input terminal, each output terminal having an output buffer holding cells to be transmitted by said output terminal, and said switch bus transmitting cells from said input terminals to said output terminals; and a backpressure signal circuit connected between each output buffer of each output port and each input buffer of each input port, said backpressure signal circuit sending a signal from a congested output buffer to those input port buffers which had immediately transmitted a cell to said output buffer so that said input port buffers cease transmission so that cells destined for said output buffer are stored in said input port buffers.