When I was running the IANA in the early 2000's we discussed this issue with many different experts, hardware company reps, etc. Not only was there a software issue that was insurmountable for all practical purposes (pretty much every TCP/IP stack has "Class E space is not unicast" built in), in
On Fri, Jul 26, 2019 at 9:21 PM Doug Barton <dougb@dougbarton.us> wrote: the case of basically all network hardware, this limitation is also in the silicon. So even if it were possible to fix the software issue, it would not be possible to fix the hardware issue without replacing pretty much all the hardware.
So the decision was made to start tooting the IPv4 runout horns in the hopes that folks would start taking conservation of the space seriously (which happened more often than not), and accelerate the adoption of IPv6. *cough*
Hi Doug, That's what you wrote. Here's what I read: "We decided keep this mile of road closed because you can't drive it anywhere unless the toll road operators in the next 10 miles open their roads too. What's that you say? Your house is a quarter mile down this road?** La la la I can't hear you. Look, just use the shiny new road we built over in the next state instead. Move your house there. The roads are better." ** Not every unicast use of 240/4 would require broad adoption of the change. Your reasoning that it does is so absurd as to merit outright mockery.
So no, there were exactly zero "IPv6 loons" involved in this decision. :-)
No, when I said IPv6 loonies, reasoning of this character was pretty much what I was talking about. Regards, Bill Herrin -- William Herrin bill@herrin.us https://bill.herrin.us/