Research Of Embedded IPv4 And IPv6 Dual Protocol Stack Network Gateway System

The IPv4 protocol was designed 25 years ago. With the development of the Internet, the shortcomings of IPv4 appear. First, the IPv4 address will be used up; Second, IPv4 has little support on network security and QoS; Last, IPv4's routing structure is too weak to keep up with the growth of routing table. To solve the problems of IPv4, The IPng working group of IETF put forward a draft called"The Recommendation for the IP Next Generation Protocol"in 1994. They confirmed the IPv6 protocol specification in 1995.IPv6 will replace IPv4 sooner or later. But IPv6 is not compatible with IPv4, so in the near future, IPv6 will be used with IPv4 together. Researchers must develop some kinds of technique to make the transition from IPv4 to IPv6 smoothly and the technologies should be effective and transparent to end users. We research the embedded IPv4 and IPv6 dual protocol stack network gateway system. This gateway system is a combination of embedded operating system and embedded applications. It's based on FreeBSD operating system and can be running on x86 compatible computers. Its main function is to connect IPv4 and IPv6 network via tunnels, plus routing and firewall.In this paper, at first, the problems of IPv4 are analyzed and the main difference between IPv4 and IPv6 is compared and IPv6 protocol family is introduced briefly and some technologies that used to migrate from IPv4 to IPv6 are enumerated. Then, we introduced the characteristic of FreeBSD, an open source operating system. There are some key points for developing embedded system under FreeBSD, such as memory file system, configure BSD kernel, crunched program and modify BSD startup procedure, etc. Finally, we explain how to make the embedded IPv4/IPv6 dual protocol stack network gateway system and how to use it. We also introduce two experimentations to validate the system's ability to connect IPv4 and IPv6 network via tunnels.By participating in this research work, we not only accumulate experience on embedded system making and IPv6, but also provide an useful product to end users to protect their investment on IPv4 software and hardware, help them to migrate from IPv4 to IPv6 favoring.