To provide a network capable of constituting an aggregation of a communication path only by setting LLDP and designating a port for making up an aggregation group, without incorporating a protocol for performing aggregation of a communication path.

In the network, node devices (31, 32) detect a connection with an adjacent node and perform management using the LLDP. The node devices (31, 32) include means (control packages 1, 11) constituting the aggregation group of the communication path with the adjacent node by using interaction of frame of the LLDP.