Re: What transition?
IPv4 gets hobbled by nat hacks, due to address exhaustion.
IPv6 fixes this.
Your argument against this is that the fix is bad because of potential broken implementations?
As for backwards compatibility, you have dns64, nat64, 6over4, 6in4. How would you get true backwards compatibility on a lower level?
Sure, the protocol could have been designed so that ipv4 routers could still route traffic if the ip6 header was contained in an ip4 header with an ip address of "some ip6 gateway", but:
1) That will not help end systems, only core routers, and as with other things, it's the "last mile" that's the issue. Most routers are already natively IP6.
2) Extra overhead and processing required unnecessarily for Ip6 networks.
3) You are basically just enforcing an always "6in4" - no point. For those routers that require it, just run your ip6 in 6in4 without forcing it where it's not needed.
so that's the network sorted.
For the hosts, how do you make a new Ip protocol with a bigger address range that is compatible with current IP4 hosts?
Ipv6 is already as fully backwards compatible as it can be.
Biting the hand that feeds IT
