Patent ID: 7885181

Claim:
A node system for a network formed by a plurality of nodes communicatively coupled as a ring, comprising: a working node that selectively drops a frame destined for a terminal hosted by the working node among frames transmitted on the ring and adds a frame from the terminal hosted by the working node to frames transmitted on the ring; a back-up node that lets a frame destined for a terminal hosted by the back-up node pass through to the working node and discards a frame from the terminal hosted by the back-up node; and a function selection unit selectively enabling one of the working node and the back-up node based on a failure of the working node, wherein in use in the network, both the working node and the back-up node are incorporated in the ring to constitute part of the ring, and the terminal hosted by the working node is also hosted by the backup node, and the working node and the back-up node are assigned the same identifier as an identifier by which each node apparatus included in the ring identifies another.