Patent ID: 6442134
Filing Date: 2002-08-27
Classification: H04J,H04L,H04Q,Y10S

Abstract:
A communications network comprising:a plurality of nodes interconnected in a ring architecture; a pair of counter-rotating packet-based rings interconnecting said nodes to establish virtual connections therebetween; and each of said nodes including a ring interface and a packet switch connected thereto, said ring interface comprising means for extracting packets from either of said rings destined therefore and passing them to the packet switch, means for adding outgoing packets from the packet switch to either of said rings, and means for passing packets directly through on each of said rings not destined for that node, whereby a virtual mesh structure is established between said nodes, and wherein each of said nodes can be configured either: a) to transmit packets on both said rings, in which case(i) in the absence of a fault each of said nodes is configured to select one of said rings from which to receive packets, (ii) if only one of the said rings has a fault, each of said nodes is configured to select an other of said rings which is free of faults from which to receive packets, and (iii) if both said rings have faults, each of said nodes is configured to select both said rings from which to receive packets; or b) to receive packets from both said rings, in which case(i) in the absence of a fault, each of said nodes is configured to select one of said rings on which to transmit packets dependent on the destination of the transmitted packets, and (ii) in the presence of a fault each of said nodes is configured to alter its transmitting behaviour to broadcast packets on both said rings.