alt Hacker News> I can read one at a glance and the other makes me fill in the blanks myself after having to count how many invisible blanks I need to fill in.
The protocol chosen for IPng, SIPP, did actually have "only" 64 bits, but this was deemed not enough as folks did not want to have to worry about running out again (amongst other reasons), and so tweaked it to have a fixed 128 bits:
* https://datatracker.ietf.org/doc/html/rfc1752
SIPP originally was variable-length capable, but it was decided fixed-length was better (e.g., for hardware like ASICs).
> Wouldn't have been a problem if they hadn't given every square millimeter of the planet 100 billion addresses.
For the record: IPv6 gives 10¹⁷ addresses per mm²; in terms of volume, 10⁸ IPv6 addresses per mm³ throughout the Earth.
You're right, my 100B per square millimeter undershot by six orders of magnitude.
I woulda thought 18 quintillion would've been enough addresses for the next century or two but good thing we locked in all this extra data we throw away with a '::'.
I'm sure it was all well considered by intelligent people, but it was still a dumb decision.