IPv6 transition technologies

Before IPv6 dominates the Internet, high-efficient and seamless IPv6 transition technologies are needed to enable communication between IPv4 and IPv6 networks. Several IPv6 transition technologies can be used in different environments and periods, such as dual stack (RFC 2893) and tunneling (RFC 2893).

Dual stack is the most direct transition approach. A network node that supports both IPv4 and IPv6 is a dual stack node. A dual stack node configured with an IPv4 address and an IPv6 address can forward both IPv4 and IPv6 packets. For an upper layer application that supports both IPv4 and IPv6, either TCP or UDP can be selected at the transport layer, whereas the IPv6 stack is preferred at the network layer. Dual stack is suitable for communication between IPv4 nodes or between IPv6 nodes. It is the basis of all transition technologies. However, it does not solve the IPv4 address depletion issue because each dual stack node must have a globally unique IP address.

Tunneling is an encapsulation technology that utilizes one network protocol to encapsulate packets of another network protocol and transfer them over the network. For more information about tunneling, see "Configuring tunneling."