One use case: ISP who wants to provide IPv4+IPv6 to customers, but does
not have enough IPv4 addresses for everyone, so has to NAT anyway, and
wants to simplify the operation of its edge network by running only one
protocol.
Quite popular with 3GPP folks since they have zillions of customers and
are already NATing them in IPv4-only, and their handsets all run
applications coded in a high-level language like Java and therefore
support IPv6 by default. The notable exception being Skype...
As soon as you provide IPv6, you have a huge chunk of your traffic that
is IPv6: Google, Facebook, Youtube, Akamai, etc. So NAT64 is only used
for the remaining mom and pop shops, and www.openbsd.org. And that
fraction of IPv4-only hosts is diminishing and all signs point to that
trend continuing.
So these 3GPP providers can go from "NAT everything" to "NAT a little"
by deploying NAT64. Why would anyone in their right mind not consider that?
Simon
