COMMUNICATION NETWORK SYSTEM

PROBLEM TO BE SOLVED: To easily grasp the existing PVC(permanent virtual circuit) setting situation of a whole ring, and to easily and accurately set a ring PVC. SOLUTION: In an NMS(network management system) 220, an individual PVC information collecting application 205b collects individual PVC information from each node device in a ring network under control, and integrally works the individual PVC information, and generates and manages ring PVC information. A ring PVC display application 205c displays the list of the ring PVC information. Then, a ring PVC setting application 205d sets a ring PVC while viewing the list display. When the ring PVC is set, a ring PVC check application 205e checks the state of a communication path being the target of the ring PVC setting based on the ring PVC information which is already under control, and issues waning corresponding to the path state.