A method for detecting a duplicate address, wherein a mobile station is moving from a second access network pertaining to a second network element into a first access network pertaining to a first network element, wherein: - the mobile station sends a request message to the first network element; - the first network element generates and sends a first message to the mobile station upon reception of said request message, said first message designating an explicit address configuration and including prefix information; - the mobile station checks out the explicit address configuration, generates an address based on said prefix information, wherein the mobile station presumes that the generated address is a valid address, and sends a neighbor solicitation message containing the generated address to the first network element for indicating that the mobile station requires registering the generated address with the first network element without the first network element waiting for confirmation on a uniqueness of the generated address from other network elements, which has been presumed a valid address by the mobile station; and - the first network element creates an entry for the mobile station if the generated address is not found in its address table without waiting for the confirmation on the uniqueness of the generated address from the other network elements, or generates and sends a second message to the mobile station for indicating that the generated address is a duplicate address if it is found in its address table and discards data packets with the duplicate address sent from the mobile station, wherein, if no instruction is obtained from the first network element, the mobile station continues to use the generated address as a Care-of-Address, CoA, wherein the generated address is not used as a tentative address but as a target address. - the mobile station sends a request message to the first network element; - the first network element generates and sends a first message to the mobile station upon reception of said request message, said first message designating an explicit address configuration and including prefix information; - the mobile station checks out the explicit address configuration, generates an address based on said prefix information, wherein the mobile station presumes that the generated address is a valid address, and sends a neighbor solicitation message containing the generated address to the first network element for indicating that the mobile station requires registering the generated address with the first network element without the first network element waiting for confirmation on a uniqueness of the generated address from other network elements, which has been presumed a valid address by the mobile station; and - the first network element creates an entry for the mobile station if the generated address is not found in its address table without waiting for the confirmation on the uniqueness of the generated address from the other network elements, or generates and sends a second message to the mobile station for indicating that the generated address is a duplicate address if it is found in its address table and discards data packets with the duplicate address sent from the mobile station,