[ghshephard]

Just to nitpick a bit. What people typically mean when they say "IPV4 NAT" is Network and Port translation. My 192.168.0.1 internally becomes 172.217.12.100 and my port gets converted to something that is tracked so that the return packet can find it's target.

In IPv6, Prefix-Translation is similar, in that the /64 prefix is translated 1:1 - but the /64 Host address is (in my experience) left alone - so that renumber a network becomes trivial when you change ISPs - you just just change the prefix.

I don't actually know if "IPv4 NAT" behavior even exists in the IPv6 world, except in the form of a lab experiment.

[endmon]

From my understanding, the "IPv4 NAT" equivalent for IPv6 is generally referred to as NAT66 (NPTv6 for Prefix-Translation). For example, Fortinet offers this on their firewalls, and I believe most firewall vendors have this option.

[zamadatix]

What they're saying is NAT66 on Fortigates is 1:1 NAT, i.e. prefix translation, not n:1 NAPT, i.e. address+port translation.

I can't imagine why one would ever intend to use NAPT over NAT when the addresses were available though (e.g. on IPv4 where having a minimum of 2^64 public addresses per connection is not assumed), which is the only reason I wouldn't expect anyone to have bothered implementing it. So sure, it's what people refer to on IPv4, but it's not materially different from 1:1 NAT or necessarily adding any additional value.

[reincarnate0x14]

You can do the many-to-few (or one) NAT behavior with port rewrites in IPv6 if you want to, there are just few circumstances it makes any sense.

FWIW the broad IPv6 network-prefix NAT behavior ALSO EXISTS in IPv4, it's just less applicable.