Patent ID: 6128306
Filing Date: 2000-10-03
Classification: H04L,H04Q

Abstract:
A routing switch for transmission of digital signal cells of at least two different types, which switch has a plurality of input ports for receiving input cells, and a plurality of output ports for outputting output cells, each output port having circuitry to identify at least one output queue of cells awaiting output by that output port, buffer circuitry selectively connectable to both said input and output ports for holding a plurality of cells of each type after receipt by an input port and prior to output by an output port, and control circuitry for determining whether each input cell at an input port is a said first or second type and determining to which output queue, or queues, the cell should be added, said circuitry for each output port comprising a respective memory region for each output port providing a chained list of addresses identifying buffer locations of cells forming the queue for that output port and a pointer store for front and back pointers to said respective memory region to identify a front and end of the queue for the output port;wherein said control circuitry includes input circuitry and output circuitry, said output circuitry being operable to form a plurality of queues of cells awaiting output at said output ports and to output each cell from a queue in a multi-bit frame including a digital signal cell and control bits, said input circuitry being operable to respond to said control bits to control the selection of each output port and queue for each cells;wherein said control circuitry is responsive to said control bits to form a plurality of queues at each output port; andwherein said control bits include a priority indicator for each cell and said control circuitry is operable to provide a plurality of queues of respective different priority levels at each output port.