Please don't try to engineer other people's networks because they are
not going to listen to you. It is a fact that 240/4 addresses work fine
except for one line of code in IOS, MS-Windows, Linux, BSD, that
explicitly disallows packets with this address. People have already
provided patches for Linux and BSD so that 240/4 addresses work
normally. Cisco would fix IOS if the IETF would unreserve these
addresses, and likely MS would follow suit, especially after Cisco makes
their changes.

Now, please explain the magic method you're going to use to cause that
"one line of code" to be removed from more than a billion devices that
are currently able to use the Internet.

Remember that a lot of these devices are deployed in spots such as little
gateway NAT devices owned by John Doe at 123 Anydrive, and so when he is
unable to get to some website because some brilliant hosting service has
chosen to place a bunch of servers on, his reaction is most
likely going to be "so and so sucks" and move onto a competitor's web

Further, when one of your magic clients with the "updated" version of
Windows XP that supports "IPv4-240+" and the misfortune to actually *BE*
on one of those decides to contact pretty much any existing website on a
VPS that's on "auto pilot", and there's a ton of those, dontchaknow, we
are talking a problem significantly worse than "failed to update bogon
filters". Not only does the hosting company have to fix their bogon
filters, but they also have to fix the TCP stack on every server under
their control, which is going to be extremely labor intensive.

Do we want to start discussing all the other places that knowledge of
network classes is built into software, and the subtle ways in which things
may break, even if they appear to "work" for some crappy definition of

Please don't try to re-engineer the entire IPv4 Internet because you'd like
a small additional allocation of IP space that isn't currently usable.

... JG