In a wide area Ethernet network, an edge side gateway (EGW) acquires layer 2 tunneling control information from an authentication server when a PADI is received from a user terminal, stores the correspondence between the source address of the PADI and the layer 2 tunneling control information in its management table, encapsulates the PADI in accordance with the layer 2 tunneling control information, and transmits the encapsulated PADI packet to the wide area Ethernet network. A core side gateway (CGW) having received the encapsulated PADI packet stores the correspondence between the tunneling control information and the source address extracted from the received packet in its management table, and forwards the PADI obtained by decapsulating the received packet to a broadband access server. Thereafter, each of the EGW and CGW forward received packets for the user after converting their format by referencing to the management tables.