NAT64

NAT64 is an IPv6 transition mechanism that facilitates communication between IPv6 and IPv4 hosts by using a form of network address translation (NAT). The NAT64 gateway is a translator between IPv4 and IPv6 protocols, for which function it needs at least one IPv4 address and an IPv6 network segment comprising a 32-bit address space. NAT64 is an IPv6 transition mechanism that facilitates communication between IPv6 and IPv4 hosts by using a form of network address translation (NAT). The NAT64 gateway is a translator between IPv4 and IPv6 protocols, for which function it needs at least one IPv4 address and an IPv6 network segment comprising a 32-bit address space. An IPv6 client embeds the IPv4 address it wishes to communicate with using the host part of the IPv6 network segment, resulting in an IPv4-embedded IPv6 addresses (hence the 32-bit address space in the IPv6 network segment), and sends packets to the resulting address. The NAT64 gateway creates a mapping between the IPv6 and the IPv4 addresses, which may be manually configured or determined automatically. A simple NAT64 installation may consist of a gateway with two interfaces connected to an IPv4 network and an IPv6 network, respectively. Traffic from the IPv6 network is routed via the gateway which performs all the necessary translations for transferring packets between the two networks. However, the translation is not symmetric, as the IPv6 address space is much larger than the IPv4 address space; thus, one-to-one address mapping is not possible. The gateway maintains IPv6-to-IPv4 address mapping, which may be established manually (stateless mapping) or automatically (stateful mapping) when the first packet from the IPv6 network reaches the NAT64 gateway.