Actually, IPv4 address can be mapped to the IPv6 address space and routed across an IPv6-only network; you have stateless NAT gateways at the edges. That allow

Actually, IPv4 address can be mapped to the IPv6 address space and routed across an IPv6-only network; you have stateless NAT gateways at the edges. That allows network operators to manage a single-stack network while still giving users an IPv4 network. 464XLAT adds one more component to the picture, which is a stateful NAT gateway that allows a network operator to provide limited IPv4 service without giving each user a public IPv4 address. For reference: https://en.wikipedia.org/wiki/IPv4_mapped_address#IPv4-mapped_IPv6_addresses https://en.wikipedia.org/wiki/IPv4_mapped_address#IPv4-mappe...