The explosive growth of the current Internet, which operates using Internet Protocol version 4(IPv4), has created a number of problems for the administration and operation of the global network and the new internet service. These problems include the shortage of IPv4 address, the lack of QOS and security function, and the rapid growth of memory and performance requirements for network routers. Internet Protocol version 6(IPv6) has been designed to solve these problems by IETF.
This thesis suggests the stepwise transition strategy from IPv4 to IPv6 for the incumbent carrier who is the internet service provider(ISP) and network provider. For the estimation of the demand of IPv6 address, Two scenarios, explosive growth and steady growth, were designed to the mobile internet access and the digital appliance. For the next step, I designed the four alternative network models and the six transition paths between each alternative model. Finally, I evaluated the each transition path using the tunneling complexity, traffic processing capability, and economic factor for the selection of the optimal transition strategy.