NPTv6

NPTv6 stands for Network Prefix Translation for IPv6, a proposed method for translating IPv6 addresses by altering the network prefix while keeping the interface identifier intact. The goal is to enable renumbering and address reuse without requiring changes to each host’s configured address or to applications. In typical deployments, a translation function at a network boundary rewrites the source or destination prefix according to a fixed mapping between the original and new prefixes.

Operationally, NPTv6 is intended to be simpler than NAT at the transport layer. It focuses on prefix-level translation rather than port-based mapping and is usually implemented on edge routers or customer premises devices that connect a site to the wider Internet. By preserving the lower 64 bits of the IPv6 address, NPTv6 aims to keep stable host identifiers while allowing the network prefix to change, supporting renumbering without per-host reconfiguration.

Status and adoption: NPTv6 has been described in IETF discussions and drafts as an option for address renumbering, but it has not been standardized in an RFC and has seen limited public deployment. It competes with other IPv6 renumbering approaches and NAT-related techniques such as NAT64, while inviting debate about end-to-end semantics, routing complexity, and the potential need for DNS updates and ACL adjustments.

See also: IPv6 address architecture; IPv6 renumbering; NAT66; NAT64.