IPv6 transition technologies

IPv6 transition technologies enable communication between IPv4 and IPv6 networks.

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. An application that supports both IPv4 and IPv6 prefers IPv6 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 IPv4 address.

Tunneling uses one network protocol to encapsulate the packets of another network protocol and transfers them over the network. For more information about tunneling, see "Configuring tunneling."

Network Address Translation – Protocol Translation (NAT-PT) enables communication between IPv4 and IPv6 nodes by translating between IPv4 and IPv6 packets. It performs IP address translation, and according to different protocols, performs semantic translation for packets. This technology is only suitable for communication between a pure IPv4 node and a pure IPv6 node.

6PE enables communication between isolated IPv6 networks over an IPv4 backbone network.

6PE adds labels to the IPv6 routing information about customer networks and advertises the information into the IPv4 backbone network over internal Border Gateway Protocol (IBGP) sessions. IPv6 packets are labeled and forwarded over tunnels on the backbone network. The tunnels can be GRE tunnels or MPLS LSPs.

6PE is a highly efficient solution. When an ISP wants to utilize the existing IPv4/MPLS network to provide IPv6 traffic switching, it only needs to upgrade the PE routers. In addition, the operation risk of 6PE is very low.