You have to go back further in time and hit the designers of IPv4 on the head for not making it forward compatible.
IPv6 is as backward compatible as is possible within this constraint.
You can embed IPv4 space within IPv6, there is NAT64, tunneling IPv6 over IPv4 and many other transition technologies.
It's not possible to design a protocol that is any more backwards-compatible.
IPv6 is as backward compatible as is possible within this constraint. You can embed IPv4 space within IPv6, there is NAT64, tunneling IPv6 over IPv4 and many other transition technologies. It's not possible to design a protocol that is any more backwards-compatible.