.ipv4/ipv6 Transition

With the rapid development of Internet, the inflation of network scale, the complicatedness of structurethe and the diversification of service type, the widely used IPv4 protocol has exposed a lot of faults since IPv4 was recommended by Jon Postel in RFC791 in the 1981, for example, the impending exhaustion of the IPv4 address space, the severe problem of QoS and security, etc. To solve the problems thoroughly, the IETF (Internet Engineer Task Force) had put forward and designed the IPv6 protocol, the next generation network protocol. It has one hundred and twenty eight bits address, which can effective solve the shortage of IP address. Besides it, IPv6 protocol takes many new technologies, which includes the more highly effective IP header, the good QoS and the automatic configuration of host address; all these characters greatly satisfy the needs of the users and leads to the inevitable transition from IPv4 to IPv6.However, the current Internet network is based on the IPv4 protocol and still has lots of the IPv4 hosts and network equipments, so it is unpractical to rapidly complete the transition from IPv4 to IPv6. Therefore, it has the important academic and practice meaning for us to implement the fluent and seamless and secure transition from IPv4 to IPv6.This thesis draw a conclusion on the inevitable transition from IPv4 to IPv6 by comparing and analyzing IPv4 and IPv6 protocol including their shortage and advantage, and expatiate a few kinds of classic transition technology from IPv4 to IPv6 such as dual stack, translation, tunnel technology. The principal duties of this thesis are: Implementing a transition experiment from IPv4 to IPv6 by building the simulation laboratorial hardware flat to measure host connectivity; Implementing a kind of network chat application independent to protocol by VC6.0 programming. This is a probing work in the IPv4/IPv6 transition phase. All research work has the important academic and practical application value for us to use the transition technology from IPv4 to IPv6 and deploy the IPv6 network.