COMMUNICATION SYSTEM

PROBLEM TO BE SOLVED: To construct an integrated network with ease and at a low cost, to increase communication capacity and to unify the whole managing operation by hierarchically connecting plural networks by an ATM switch so as to communicate through an ATM communication path and transmitting and receiving controlled monitor information through an ATM cell. SOLUTION: A high-order system loop L0 and first/second low-order system loops L1, L2 are connected respectively via node devices N2, N3, and a third low-order loop L3 is housed at the low-order of the loop L1 via the node device N5 of the loop L1 in the integrated network. A network-managing device NM1 unitarily executing the operation management of the integrated network connected to a node device N1 to monitor and control through a monitor and control path set between the node devices of the respective loops L0 to L3. Communication between the terminals of the respective nodes is executed through a user path for communication, etc., the respective node devices connect the high-order and low-order loops via an input/output port by an ATM SW.