The Research And Realization Of Gateway Based On NAT-PT Translation Technology

Because IPv6 has extended address space, bran-new IP packet header options,QoS Support and enhanced Flow-Label, and some other perfect and safe mechanism characteristic, it will substitute the IPv4 inevitably. At present the task is to transit from current network based on IPv4 to the next generation network based on IPv6 gradually, smoothly, seamless, and with reasonable price.At the early stage of this gradual transition, Internet is composed of the"ocean"that run IPv4 and the"island"that run IPv6. And gradually, the"ocean"of the IPv4 will size down, but the small area of IPv6"island"will be more and more. It will replace IPv4 completely in the end. In the course of transition from IPv4 to IPv6, we must resolve two problems: the communication on the IPv6 network which be isolated by the network of IPv4 and the communication between the IPv6 network and the IPv4 network.The gateway based on the NAT-PT (network address translation-protocol translation) is a powerful evolution tool in the course of transition from IPv4 network to IPv6 network. The NAT-PT transition technique can insure the co-existence and inter-working of the IPv4 network with the IPv6 network. The communication can initiate from any kind of host inside any net arbitrarily, and do not need any change on the net outside of the gateway. In virtue of adoption of translation gateway project, what the ISP need to do is some correlative work in IPv6 while the translation gateway will ensure the uninfluenced service and function of the network, thus the difficulty of upgrade recedes.In this paper, I research into the translation gateway based on the NAT-PT technology, design and realize the prototype system. The work I do on this thesis involves such aspects as follows:1) Thoroughly analyze the work principle and mechanism of translation gateway that base on the NAT-PT technical, the algorithm of PT(protocol translation)and the algorithm of NAT(network address translation) in the NAT-PT;Thoroughly analyze the work principle of DNS-ALG in NAT-PT.2) Put forward the search algorithm lookuping the translation entries in high speed network environment according to the Patricia tries along with Hash tables, which will speedup the search process of translation entries and improve the performance of NAT-PT.3) Analyze and summarize the characteristics of NAT-PT model, and put forward the enhanced model ENAT-PT, it has the great significance in actual application of resolving the problem of IP address limitation of IPv4.4) Through researching on the work principle of NAT-PT,Put forward the design project of NAT-PT,utilize the software Click modular router system,realize the NAT-PT translation gateway prototype system.The research work in my paper is affiliated with the Chinese nation development and reform committee with Japanese economic industry province together project:"The IPv6 cooperative project of the next generation Internet that organizes by China and Japanese"sub-item"the transition technique research that from IPv4 applications to IPv6 applications"that be taken on by Southeast University.