Leveraging Class E address space to mitigate IPv4 exhaustion issues in GKE (opens in new tab)

So long as you don't have to care about Android, maybe.

"IPv4 still can't access IPv6. IPv6 can't access IPv4."

I guess my point is that these statements represent choices made by humans. Leaving the decimal representation aside, I don't get why they made these choices. If every IPv4 address were a valid IPv6 address, then these statements wouldn't be true.

If 32 bit IPv4 addresses are valid IPv6 addresses without fiddly NAT64/DNS64 shenanigans, then (it seems to me) IPv4-only clients could blithely continue to interact with the IPv4-accessible internet via IPv6-only servers, routers, etc. indefinitely. They can putter along accessing only a subset of available resources forever and everyone can passive-aggressively roll their eyes at them and close support tickets saying "upgrade to IPv6 if you want to see the rest of the internet, it just works."

That's what I mean by backwards compatible. Everyone who says "it can't be done, it has to be this way" is asserting that there's no better alternative to NAT64/DNS64 and running two entirely separate networking stacks in parallel. I don't buy that there was no simpler way to accomplish packing 32 bits into a space that can contain 128 bits. And if "supporting IPv6" simply meant "upgrading your networking software to the latest version, which transparently handles both IPv4 and IPv6 traffic for you" then networking and server teams have no excuse to avoid deploying IPv6 support for 26 years.

I recognize that 128 bit addresses will be truncated and packets misdirected or rejected if handled by a 32 bit networking stack. I recognize that clients upgrading too early will fail and need to fall back. But making it unnecessarily difficult for servers and routers to handle IPv4 traffic in an IPv6-only context led us to where we are today.

To illustrate my point: ascii text works just fine, with no translation layer required, when parsed and transmitted as UTF-8.

Seems a bit strange to me that they didn't, given how you'll want to use some sort of ingress anyway, so IPv4 could be delegated to those edge points.

"Answer: We go through every place that 4-byte IPv4 addresses appear, and allow 16-byte IPv6 addresses in the same place."

As though this is any easier than just introducing IPv6 as a new, parallel protocol that does not have to interoperate (because IPv4 still works). I'm sure he can update his software and systems but what about the thousands of other programs and billions of other machines.