A method for detecting and regulating subnet identifier overlap on a power line communication network includes a communication module. The communication module includes an identifier generating means for generating at least two identifiers for identifying a home subnet; an identifier setup means for generating an identifier different from identifiers of outside subnets; an identifier storing means for storing the generated identifiers; a transceiver for broadcasting a data packet including at least one identifier among at least two identifiers over a communication network; a comparing means for comparing the identifiers included in the received data packet with corresponding identifiers identifying its home subnet; and an overlap detecting means for determining whether more than one subnet uses the corresponding identifier when a part of at least two identifiers included in the received data packet is the same as the identifier identifying its home subnet and the remaining part is different.