With the limited addresses in the IPv4 space,
NAT was required
to translate private, non-routable IPv4 addresses to one or more
globally-routable IPv4 addresses. For organizations using IPv6 addressing,
there is no need to translate IPv6 addresses to IPv6 addresses due
to the abundance of IPv6 addresses. However, there are
Reasons to Use NPTv6 to translate
IPv6 prefixes at the firewall.