There is a weird persistent idea that all anyone really needed to do was "extend ipv4 addresses" and everything ipv4 related would have remained compatible.
No, it still absolutely would have completely broken everything and anything that used ipv4, all the tools would still need to be thrown out.
There is basically no way such a proposal could work and maintain any sane level of compatibility.
Its evident right on its face, how exactly would an ipv4 only tool connect to a 64 bit "ipv4.1 address" ?
There were proposals for backwards compatible addressing schemes. But they were rejected for a "clean slate" approach. Almost 30 years later, we can see how successful that was...
EIP (Extended Internet Protocol) [0] was proposed in 1992 as a replacement for IPv4:
"EIP achieves maximum backward compatibility with IP by making the extended space appear to be an IP option to the IP hosts and routers.
When an IP host receives an EIP packets, the EIP Extension field is safely ignored as it appears to the IP hosts as an new, therefore an unknown, IP option. As a result, there is no need for translation for in-coming EIP packets destined to IP hosts and there is also no need for subnet routers to be upgraded during the transition period."
IPv6 can do that too though! 6in4 is exactly equivalent to the proposed EIP extension. EIP still splits the internet into the old legacy v4 internet and the new EIP internet that cannot communicate with the old internet, since while you can send packets to a v4-only host it won't know what to do with it. You need to preserve this extra information - and IPv4 simply cannot do that. You cannot fit more than 32 bit of information into 32 bit..
This proposal essentially ended up as part of v6 in the form of 6to4. 6to4 uses an L4 protocol rather than an IP option, but that's more or less equivalent (and since there are a fair few routers on the internet that drop packets with unknown IP options it ends up working better).
But v6 doing something has never stopped people from complaining that v6 sucks for not doing the thing in question...
Do you admin a medium or larger network? Despite the strength of your comment it also illustrates some ignorance.
"No way", "weird persistent idea".
This despite many reasonable people suggesting it.
Deploying IPv6 at scale is deploying a totally different protocal. What is irritating is that it's not just a larger set of bits, everything changed making adoption and tooling MUCH much harder.
"All the tools would need to be thrown out"
Totally and absolutely false. Because an extended Ipv4 would have the same underlying concepts you could modify the tools and continue to use them.
From address assignment (3 ways now) to the dynamic address privacy extensons (don't actually play well with IPSEC configs) to doing renumberings on prefix changes (100% nightmare) to all the training / learning new things (costs money in bigger orgs) they seem to have purposely made this change extremely hard.
Good news, I'm on board more or less with the migration at this point, and if I am a good marker of average reasonable interested in new things but not wasting tons of time then this is a good sign.
But boy they could have made this whole thing easier
Maintaining compatibility was never an option. But the most sensible solution to running out of address space is simply to extend the address space. Instead IPv6 decides to change the format into something which is not really human readable, and decides to kill NAT as well. Which was really a terrible decision imo. I like NAT, I like having addresses that I can remember, and I hate the idea of having a unique globally routable address for every device.
The primary argument for adopting IPv6 is that IPv4 will be exhausted. Not that there’s something good about IPv6 that I would want to have. Personally I hope it never succeeds in getting sufficient adoption, so that eventually we can have a good IPv7 that’s just a bigger version of IPv4.
That's not all that IPv6 changed. There is a reason even places like google cloud have not implemented ipv6 (and these are huge scale players). They changed so many things around the protocol that you need new firewall experts, new configuration experts etc etc
No, it still absolutely would have completely broken everything and anything that used ipv4, all the tools would still need to be thrown out.
There is basically no way such a proposal could work and maintain any sane level of compatibility.
Its evident right on its face, how exactly would an ipv4 only tool connect to a 64 bit "ipv4.1 address" ?