Implementing NAT-PT/SIIT, ALGs and consideration to the mobility support in NAT-PT environment

To deploy IPv6 we need some transition mechanisms that help existing IPv4 users move to IPv6 easily. NATPT (Network Address Translation - Protocol Translation, RFC-2766) is a transition mechanism which supports communication between the IPv6 node and 1Pv4 node by translating header of IP packet. NAT-PT uses IPv4/IPv6 header translation rules specified in SIIT (Stateless IP ICMP Translation, RFC-2765). Since NAT-PT is a technology based on NAT (Network Address Translation) it has the same characteristics as what NAT has. So it needs ALG (Application Layer Gateway) for a specific application layer protocol embedding IP address in its payload. Especially DNS-ALG is the most important thing than any other one. Because it discovers IPv6 address for IPv4 node from its IPv4 address. In this paper, we suggest effective DNS-ALG mechanism. MIPv6 (Mobile IPv6) is another hot issue in IP networking area. If NAT-PT is used in MIPv6 environment NAT-PT needs some modifications to guarantee seamless MIPv6 operation. We also suggest the issues regarding mobility support in NAT-PT environment.