Patent ID: 7002981
Filing Date: 2006-02-21
Classification: H04L,H04Q

Abstract:
1. An arbitration method for use in selecting the connections to be made between ingress and egress ports of a memoryless cross-bar switch of a data switching system, the arbitration method comprising a three phase process involving (i) a request phase in which each ingress port sends its connection requests to the egress ports to which a connection is required, (ii) a grant phase in which each egress port examines in a round-robin manner the requests directed to it using a grant pointer, and selects one request for grant returning a grant signal indicative of the selected request and directed to the ingress port which sent the selected request, and (iii) an accept phase in which each ingress port examines in a round-robin manner the received grant signals and selects one to accept thereby defining an ingress to egress port connection across the cross-bar switch, characterized in that the transition sequences for each of the grant pointers are mutually exclusive; in which the mutually exclusive transitions are determined by a connection matrix setting the pathways of request and grant signals; and wherein said connection matrix may be represented by a table having columns representing respective egress ports, the entries in the table along any colunm represent, in vertically descending order, the ingress ports to which the grant pointer of the corresponding egress port points, and the table does not contain, in the same vertically descending order, multiple instances of any combination of a first ingress port and a second ingress port.