4over6: Network Layer Virtualization for IPv4-IPv6 Coexistence

IANA exhausted its IPv4 address space in 2011, and IPv6 is the next generation to replace IPv4. However, the IPv6 transition techniques are still immature and holding back the development of the next-generation Internet. Hence, IPv4-IPv6 coexistence is becoming increasingly imminent. During the coexistence period, the Internet will consist of IPv4-only, IPv6-only, and dual-stack segments. Both the network infrastructure and operations must support IPv4-only, IPv6-only, and dual-stack accordingly. This article develops a 4over6 virtualization architecture that virtualizes IPv4-only networks over IPv6-only networks. This architecture enables two IPv4-only segments to communicate over an IPv6-only network by using an IPv4-in-IPv6 tunnel. The architecture can be examined in different areas such as addressing schema, layer 3 routing, and packet forwarding. The 4over6 virtualization architecture is being standardized in IETF. Various implementations and deployment scenarios are actively discussed in the ISP and vendor communities.