Patent ID: 6661800
Filing Date: 2003-12-09
Classification: H04L

Abstract:
A communication network system, wherein a plurality of node devices and a control node device that controls said plurality of node devices are connected in a ring shape by means of ring circuits that can set a first communication path and a second communication path in a direction opposite to that of the first communication path and that during normal operation carries out transmission of data through the first communication path between each of the node devices or between communication terminals connected to each of the node devices,wherein the control node device comprises control means that issues loopback instructions or loopback release instructions to an arbitrary node device, and each of said plurality of node devices comprises control means which loopbacks the first communication path to the second communication path on both left and right sides of the ring circuits as seen from the devices themselves simultaneously based on the loopback instructions and which releases the loopback based on the loopback release instructions.