I assert that regardless of whether NAT66 is a good or a bad thing, anything that layers on IPv6 must be NAT66 tolerant. While folk can postulate alternative universes in which enterprises will not demand or vendors refuse to implement NAT66, there is another area that is harder to wish away. Observation: Without NAT44 the internet would already have run out of address space. I don't think this can be seriously disputed. Observation: Without NAT46 and NAT64, we cannot transition from IPv4 to IPv6. OK, so when I first started making this claim I was widely dismissed as a fool, a lunatic and other unpleasant things. I think that it is now very clear that the IPv6 transition will take at least another decade to be near completion and that large parts of the net will not support IPv6 access for many years to come. Contrawise, consumers and enterprises are going to require that their ISP provides Internet service that works with the devices they have, not the ones that hardware vendors might hope to sell them. When the US settled for a single lightbulb socket standard there were many different systems in use. The only reason that a transition was possible was due to adapters. The same will be true of the IPv6 transition. If we accept these two observations we arrive at a proof that NAT66 is unavoidable. It will happen any time an IPv6 device with IPv4 service attempts to connect to an IPv6 server. NAT64 + NAT46 = NAT66. _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf