PURPOSE: To dynamically relieve the connections without using an independent line for control by relieving management connections to collect required information at the time of the occurrence of a fault and performing the recovery processing of user connections based on this information in accordance with prescribed procedures.

CONSTITUTION: For example, a terminal point node 1 is completely coupled to all other nodes1 by management connections 42 to 50 and independently manages the connections. If a node 10 gets faulty, the node 1 selects a bypass avoiding the node 10 from paths of preliminarily determined standby management connections to restore the management connection. Next, the node 1 collects statistical information of the network use state, relief priority information, etc., from the other exchanges through the restored management connection and performs the network relief processing like bypass setting of user connections, band reduction of connections, or disconnection based on collected information in accordance with prescribed selection procedures.