> For one, all IPv4 addresses could also be IPv6 addresses. You have that today, all IPv4 addresses are also dualstack addresses, which is how IPv6 is normally

> For one, all IPv4 addresses could also be IPv6 addresses. You have that today, all IPv4 addresses are also dualstack addresses, which is how IPv6 is normally deployed for the transition. > There could be a straightforward translation between an IPv4 packet and an IPv6 packet and back just by prepending the address with 0s. Which doesn't help you anything because it doesn't enable IPv4 hosts to communicate with IPv6 hosts. > You could enable backbone routers to speak only IPv6 and then translate those packets to IPv4 packets only when sending them to the endpoint devices. That's called a tunnel, you can have that today. > IPv6 could have been designed as a backwards-compatible extension of IPv4, not a completely new network. What exactly is the backwards compatibility if none of that allows IPv4 and IPv6 hosts to interoperate?