IPv6-to-IPv6 Network Prefix Translation (NPTv6) is an experimental specification for IPv6 to achieve the address-independence at the network edge, given by network address translation (NAT) in Internet Protocol version 4. It has fewer architectural problems than traditional IPv4 NAT; it is for example stateless and preserves the reachability attributed to the end-to-end principle. However, the method still lacks solutions to translate embedding IPv6 addresses, for example in IPsec, and requires a more complex DNS setup (split-horizon DNS).
One use case for IPv6-IPv6 Network Prefix Translation is multihoming for small networks; this may also be implemented with DHCPv6.
References
IPv6-to-IPv6 Network Prefix Translation Wikipedia(Text) CC BY-SA