A method for registering customer premises equipments to provide an Internet service to the customer premises equipments by a network management apparatus of an access network structure, wherein the network management apparatus and the customer premises equipments are connected through a bundle cable including a plurality of lines in the access network structure, the method comprising: transmitting a registration signal toward a customer premises equipment; receiving registration response signals transmitted from the customer premises equipments 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 signals from the registration response signals; and establishing a link with the customer premises equipment connected to the properly connected line, wherein the interference signals are introduced through adjacent lines of the properly connected line among the plurality of lines, wherein the distinguishing the direct signal and the interference signals includes measuring a signal strength of the registration response signal introduced from each line, selecting one or more lines having a large signal strength, and determining whether the registration response signal introduced from each of the selected lines is the direct signal or one of the interference signals by analyzing a channel frequency response of each of the selected lines, wherein the determining whether the registration response signal is the direct signal or one of the interference signals includes calculating a characteristic curve slope in a low frequency band of the channel frequency response, and determining the registration response signal as the direct signal when the characteristic curve slope is negative, and determining the registration response signal as one of the interference signals when the characteristic curve slope is positive, and wherein the low frequency band is included in 3 MHz to 30 MHz. transmitting a registration signal toward a customer premises equipment; receiving registration response signals transmitted from the customer premises equipments 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 signals from the registration response signals; and establishing a link with the customer premises equipment connected to the properly connected line, wherein the interference signals are introduced through adjacent lines of the properly connected line among the plurality of lines, wherein the distinguishing the direct signal and the interference signals includes measuring a signal strength of the registration response signal introduced from each line, selecting one or more lines having a large signal strength, and determining whether the registration response signal introduced from each of the selected lines is the direct signal or one of the interference signals by analyzing a channel frequency response of each of the selected lines, wherein the determining whether the registration response signal is the direct signal or one of the interference signals includes calculating a characteristic curve slope in a low frequency band of the channel frequency response, and determining the registration response signal as the direct signal when the characteristic curve slope is negative, and determining the registration response signal as one of the interference signals when the characteristic curve slope is positive, and measuring a signal strength of the registration response signal introduced from each line, selecting one or more lines having a large signal strength, and determining whether the registration response signal introduced from each of the selected lines is the direct signal or one of the interference signals by analyzing a channel frequency response of each of the selected lines, wherein the determining whether the registration response signal is the direct signal or one of the interference signals includes calculating a characteristic curve slope in a low frequency band of the channel frequency response, and determining the registration response signal as the direct signal when the characteristic curve slope is negative, and determining the registration response signal as one of the interference signals when the characteristic curve slope is positive, and wherein the low frequency band is included in 3 MHz to 30 MHz.