A method for registering customer premises equipment to provide an Internet service to the customer premises equipment by a network management apparatus of an access network structure, wherein the network management apparatus and the customer premises equipment are connected through a bundle cable including a plurality of lines in the access network structure, the method includes: transmitting a registration signal toward a customer premises equipment; receiving registration response signals transmitted from the customer premises equipment through the plurality of lines; analyzing the registration response signals introduced from the plurality of lines and distinguishing a direct signal transmitted through a properly connected line and interference signal from the registration response signals; and establishing a link with the customer premises equipment connected to the properly connected line. The interference signal is introduced through adjacent line of the properly connected line among the plurality of lines.