[ppml] 240/4

[vixie at vix.com]

> Even though this is a one or two line change for the vendor, and
> the cost to write the patch is as close to zero as they get, there
> are costs to support it with zero offset in incremental revenue.

we know from botnet hunting that hundreds of thousands of win9x PC's are never
patched, and that in spite of their incredible infection levels, are still
used every day by people who buy stuff.  what this means in practice is that
no matter how easy the patch might be to produce and distribute, there will
not be sufficient uptake that anyone large enough to need space from 240/4
would ever(*) be willing to deploy it as "public unicast".  by "ever" i mean
that the heat death of the universe would be more likely to occur first, or
else, the wide scale usefulness of "public ipv6 unicast" would occur first.

so, 240/4 as an extension of RFC1918 space makes sense to me.  large ISP's
can't do enough private addressing with the space RFC1918 reserves, and so,
on the assumption that it'll be used for internal infrastructure where the
deployer will be in better control of the software revision level, that's
what i think ought to be done with it.