Implementation of 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. NAT-PT (network address translation - protocol translation, RFC-2766) is a transition mechanism which supports communication between the IPv6 node and IPv4 node by translating the IP packet header. 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 NAT. So it needs an ALG (application layer gateway) for a specific application layer protocol, embedding an IP address in its payload. Especially, the DNS-ALG is most important because it discovers the IPv6 address for the IPv4 node from its IPv4 address. We suggest an effective DNS-ALG mechanism. MIPv6 (mobile IPv6) is another hot issue in the IP networking area. If NAT-PT is used in an MIPv6 environment, NAT-PT needs some modifications to guarantee seamless MIPv6 operation. We also suggest the issues regarding mobility support in an NAT-PT environment.