A method implemented in a network element to make a first device assigned an IPv4 private address accessible to a second device using Internet Protocol Version 6 (IPv6), the method comprising receiving an IPv6 formatted data packet, having a virtual IPv6 address as a destination address and having been sent from the second device; determining whether the virtual IPv6 address includes a representation prefix (RP); sending an address map query (AMQ) to a customer premise equipment (CPE), where the CPE stores a mapping between the virtual IPv6 address and a private IPv4 address of the first device; receiving an address map response (AMR) from the CPE with the private IPv4 address corresponding to the virtual IPv6 address; translating the IPv6 formatted data packet into an IPv4 formatted data packet; and sending the translated data packet to the CPE through an IPv4 over IPv6 tunnel.