The deployment of the next generation of the Internet Protocol IPv6 has progressed slowly. Although some commercial products have been incorporated with parts of functions of IPv6, it is still difficult to have a revolution from IPv4 to IPv6 at one night. The current users on line must be cared. As a result, the migration from IPv4 to IPv6 must begin from integrating two Internets of IPv4 and IPv6. A hierarchical routing method is purposed to improve performance of tunneling mechanisms and reduce consumption of IPv4 addresses in NAT-PT mechanisms.