Translation Spot Negotiation in IPv4/IPv6-Coexist Mesh

IPv6 offers significant advantages over IPv4. However IPv4 and IPv6 protocols are expected to coexist during a long period. Currently, there are many IPv4/IPv6 transition/coexistence technologies, which can be generally devided into two kinds: translation and tunneling. In some typical transition scenarios, both tunneling and translation are needed. However, either translation or tunneling has limitation and application scope. In addition to the IP versions of source networks and destination networks, the IP version of transport network (the middle part along end-to-end path) also plays an important role during IPv4/IPv6 transition/coexistence. Therefore, we need to decide which transition methods should be used in different typical transition scenarios and how transition and tunneling collaborate for solving transition/coexistence problems. This draft presents an IPv4-IPv6 transition/coexistence framework named PET (short for Prefixing, Encapsulation and Translation), which is a network side solution. PET includes fundamental elements needed in transition scenarios, which provides the flexibility for network operators to decide the proper transition technology. In addition, this draft also addresses how to deploy PETs and analyze the advantages and disadvantages of typical transition technologies that PET may adopt.