The Research In The Transition Scheme Of IPv4/IPv6

With the rapid development of computer networks, especially the development of Internet, IPv4 protocol has exposed a lot of faults, the most prominent is the gradually depleting of IPv4 address. To solve the problems thoroughly, the IPv6 protocol had been put forward and designed by the IETF (Internet Engineer Task Force) came into being.IPv6 has one hundred and twenty eight bits address, which can effectively solve the gradually depleting of IPv4 address. Besides it, IPv6 has some characteristics:simplified header and extension; hierarchy address architecture; Plug and Play internet working; authentication and encryption on network layer; support on service quality; better support on mobile communication. All these characters greatly satisfy the needs of the users and leads to the inevitable transition from IPv4 to IPv6.However, the transition from IPv4 to IPv6 will not accomplish in an action, and they'll coexist in a long period, especially to IPv4 that still very good support Internet at present. IPv6 is not a simple upgrade from IPv4, and because of the differences of head structure and address configuration, they are not compatible. The key that the IPv6 network whether to succeed in the future is whether to realize the smooth transition from IPv4 network to IPv6 network finally.This paper detailed introduces some concrete methods in allusion to different instance in transition period, including dual protocol stacks, tunneling technology and NAT-PT. Use OPNET to run simulation on the communication of dual protocol stacks and tunneling technology. And we draw the following conclusion in accord with dual protocol stacks's and tunneling technology's principle and simulation results:the dual protocol stacks is flexible, but hosts and routers that support it must be loaded with two protocol stacks, with two IP addresses and have the support of the Domain Name System DNS. It is a very impractical matter that the implementation of the technology needs to all hosts and network upgrade to dual stacks. Moreover greatly increase the complexity of systems and networks. However, the biggest advantage of tunneling technology is simple. Only need to encapsulate the IPv6 packets in the IPv4 packets when the IPv6 packets enter the IPv4 region, unencapsulate the IPv4 packets and restore the IPv6 packets when leave the IPv4 region. Summing up, the communication during the IPv4 and IPv6 coexistence period, the tunneling technology is more feasible, longer-term and more realistic.