You don't need two nats, you don't have to track two types of ip addresses per customer, for most of the traffic, you don't even need nat at all (youtube, faceb

You don't need two nats, you don't have to track two types of ip addresses per customer, for most of the traffic, you don't even need nat at all (youtube, facebook, etc, all support native ipv6), and statless nat64 can be simpler and less resource intensive than cgnat