Patent ID: 8072878

Claim:
A packet ring network system including nodes for sending and receiving packets, which are connected respectively to two ringlets for transferring packets therethrough in mutually opposite directions, comprising: a redundancy node including two nodes having the same address; and a client apparatus connected to the two nodes included in said redundancy node; wherein said redundancy node further comprises: packet distributing means for duplicating packets received from the ringlets and distributing the received packets and the duplicate packets to the nodes included in the redundancy node; failure detecting and indicating means for detecting an occurrence of a failure on each of the nodes included in the redundancy node and indicating the occurrence of the failure to each of the nodes; and output selecting means for, when a failure occurs on one of the nodes, selecting a packet output from the other node as a packet to be output from said redundancy node, and when in a normal state, selecting a packet output from one of the nodes as a packet to be output from the redundancy node; wherein each of the nodes included in said redundancy node comprises: client apparatus connecting means for connecting the redundancy node to said client apparatus by a link when in a normal state, and disconnecting the redundancy node from the client apparatus when a failure occurs, and wherein the redundancy node is connected with the ringlets through the packet distributing means and the output selecting means.