Design And Realization Of IPv6 Translation Gateway System Based On NAT-PT

As the next version of Intenret Protocol, IPv6 will ultimately substiutte IPv4. The new feature of IPv6 protocol gives more supports to the applications and improvements of the next generation Internet. It makes the Internet of the next geneartion a brilliant future. There is a long way to go to transit from IPv4 to IPv6, that is to say, IPv4 and IPv6 will coexist for a long time. To be an important part of the China Next Generation Internet (CNGI), the construction of the University Campus Network is being changed momently with the development of new technology. Because of difference between IPv4 and IPv6, there can't set up a direct connection between two kinds of networks. So when the campus network transits from IPv4 to IPv6, that how to intercommunicate between IPv4 and IPv6 networks becomes an important issue.On the basis of the CNGI Customer Premises Network Project, an efficient solution to intercommunicate between IPv4 and IPv6 networks is presented.In this paper, it first studies the new feature of IPv6 protocol and comparative researches IPv4 and IPv6. Then, according to the non-compatible characteristic of them, it deeply analyzes the necessity, principles and technical difficulties of IPv6 transition. Meanwhile, the paper studies various transition mechanisms, involving dual stack mechanism, tunnel mechanism and translation mechanism, and investigate technical features and application environment. Combining with practical requirement of IPv6 campus network construction, a design model of IPv6 translation gateway system based on NAT-PT, including Network Address & Port module, Protocol Translation module and DNS-ALG module, is proposed. Then it has given a detailed technical analysis of the system. At last, a simulation model of the translation gateway system is built according to the design model, and performance test is carried out to compare with the performance of the contrast model.The paper achieves module fuction of the system, and a data structure of Hash table combined with liner list is used to improve the lookup efficiency of the algorithm.The results show that the conclusion has a pratical signifacance to the construction of the campus network transits from IPv4 to IPv6.