Ask HN: Would it be easier to make Ipv4 A.B.C.D.E vs. implimenting Ipv6?

No. All the migration tools in the world aren’t worth anything in a world where zillions of devices assume IP addresses are 32-bit and don’t ship with source code and/or can’t be upgraded in the field (e.g. because there’s custom hardware implementing some of the protocol)

Also, if such a tool were possible, a tool 32to128 could be written, too.

Given that an incompatible update was necessary, there’s little difference in complexity between going for 40 bit addresses and going for 128 bit addresses.

This is not as trivial as it sounds. One of the main drivers for using a 32 bit internet address is word length of registers. Back in those days, 32-bit word lengths were pretty common and in a language like C (which is what is used for OS development), a 32-bit integer could easily be fit in a register in most machines.

While higher-level languages might use multi field values, perhaps even arrays of integers, most low-level code, including millions of kernel code still uses integers to store IPv4 addresses. Adding an extra octet to this would make it go bonkers.

We do have conversion from IPv4 to IPv6. All IPv4 addresses can be represented in the lower bytes of an IPv6 address.

That said, the main issue with the adoption is the inherent inertia is upgrading devices. These are physical devices and large corps and businesses don't tend to allocate sufficient budget to replace and update these things to their IT dept. unless there's a pressing business need.

I have some doubts A.B.C.D.E would be the best ipv4 (semi) backwards compatible solution but the IP space problem could have definitely been "fixed" easier if that's the only problem you want to fix.

Maybe a better question would be what is the most backwards compatible way to fix the IP space problem with ipv4?

IPv6 has a slight head start, the 128-bit address format and notation were decided in 1994-1995.