Patent ID: 7088710
Filing Date: 2006-08-08
Classification: H04L,H04Q

Abstract:
1. A method of transmitting information through a data switching apparatus connected to a plurality of input line end devices and output line end devices, said input line end devices transmitting protocol information packets to a data switch for transmission to specific output line end devices, the data switching apparatus comprising a plurality of input traffic manager units a plurality of output traffic manager units and a data switch, the data switch comprising a plurality of input routers, a plurality of output routers, and a memory-less cyclic switch fabric, and a switch controller, said switch fabric being controlled by said switch controller, said input traffic manager units being connected to one or more of said input line end devices, and said output traffic manager units being connected to one or more of said output line end devices, each input traffic manager unit being arranged to convert protocol information packets it receives from the respective input line end devices into fixed length cells having a header, said header indicating the output traffic manager unit connected to the output line end device to which the cell should be sent, each input router being arranged to receive cells from a respective group of said input traffic manager units, and to maintain virtual output queues for each output traffic manager unit; each output router being arranged to transmit cells to a respective group of said output traffic manager units the method comprising the steps of: (a) on the arrival of a cell from an input traffic manager unit, examining the cell header at the input router, placing it in a virtual output queue for the output traffic manager unit indicated by the cell header, generating a transfer request including the address of the output traffic manager unit indicated by the header of that cell, and passing said transfer request to the switch controller, wherein the or each of the cell headers includes message priority information, the or each of the transfer requests includes a priority code; and the switch fabric is controlled by the switch controller to connect ones of said input routers to ones of said output routers; (b) scheduling the passage of the or each of the cells across the switch fabric at the switch controller at each switch style, by using a first arbitration process to select which of said input routers to connect to which of said output routers, and controlling the switch fabric to connect the selected input routers to the corresponding selected output routers; (c) upon it being determined that a given input router is to be connected to a given output router, performing a second arbitration process at that given input router to select a single virtual output queue, from among the virtual output queues for the output traffic manager units to which the given output router sends cells, and transmitting the cell at the head of the selected virtual output queue across the switch fabric to the given output router; and transmitting the cell by the given output router to the output traffic manager indicated by the cell header.