> At the dawn of IPv6, the idea was that you could upgrade an address to IPv6 by prepending a pair of colons, as in ::1.2.3.4
No, IPv6 explicitly rejected that idea at first. Most of the other IPng proposals did have a backwards compatibility mechanism like that. I'm still sore that the least backwards-compatible proposal was the one that won.
Later the IPv6 cabal admitted their mistake and published NAT64, but at that point it was too late to make it a mandatory required service offered by any default-route router. So now we have all of this crap about dual-stack hosts instead of simply being able to upgrade to IPv6 and trust that you will not lose any connectivity.
This is basically why, twenty years after it was standardized, IPv6 is still merely the "internet of cellphones" and no closer to replacing IPv4.
As usual, DJB saw all of this decades ahead of time:
No, IPv6 explicitly rejected that idea at first. Most of the other IPng proposals did have a backwards compatibility mechanism like that. I'm still sore that the least backwards-compatible proposal was the one that won.
Later the IPv6 cabal admitted their mistake and published NAT64, but at that point it was too late to make it a mandatory required service offered by any default-route router. So now we have all of this crap about dual-stack hosts instead of simply being able to upgrade to IPv6 and trust that you will not lose any connectivity.
This is basically why, twenty years after it was standardized, IPv6 is still merely the "internet of cellphones" and no closer to replacing IPv4.
As usual, DJB saw all of this decades ahead of time:
https://cr.yp.to/djbdns/ipv6mess.html