PROBLEM TO BE SOLVED: To realize a packet processing method that utilizes an anti-multiple fault network structure able to efficiently utilize a communication network by normally operating the entire ring even on the occurrence of a fault in connecting lines or a node through the use of a double ring structure.;SOLUTION: Input terminals (411, 414) of nodes (400, 401, 402, 403, 404) are inspected and a packet is received from the input terminal normally in operation, when an object node of the received packet is coincident with the node receiving the packet, the packet is sent to a host computer and when not, whether or not the object node is a node connected just adjacent to the node receiving the packet is inspected. When the object node of the received packet is coincident with the adjacent node, the received packet is aborted, and when the object node of the received packet is not the node connected just adjacently, two packets are transmitted in duplicate via two output terminals (405, 406).;COPYRIGHT: (C)2002,JPO
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