PET-based solution for IPv4/IPv6 coexistence

IPv6 offers significant advantages over IPv4, however it will take long time to replace IPv4 with IPv6. Therefore, these two protocols are expected to coexist during the transition period. Currently, there are many transition devices deployed to solve transition problems. Most of them only use one technology (either translation or tunneling). However, any transition technology has limitation and application scope. In transition scenarios, besides IP version of source, middle and destination network, the network characteristic (a regular edge network or a backbone) has key impact on system performance of transition methods. Therefore, we need to decide which transition method should be used in some typical transition scenarios and how the transition and tunneling devices collaborate for solving transition problems. This draft introduces a smart toolbox named PET (shortfor Prefixing, encapsulation and translation) which includes all fundamental elements needed in all transition scenarios, such as the control and data plane operations of tunneling and translation. Based on PET, we propose a network side transition solution. In this framework, there deploys only one kind of transition device, i.e. PET. Through the collaboration of PETs, the transition problems can be solved. In this draft, we give the advantages and disadvantages of all transition methods PET may adopt according to IP version of source, middle and destination network, and the network characteristic.