[arin-ppml] ARIN-prop-127: Shared Transition Space for IPv4Address Extension

[George Bonser]

> It is going to take an imaginative network engineer no more than about
> 15 minutes to realize they can reclaim all of their space they are
> currently using for /30 or /31 WAN links even where they aren't doing
> NAT at all and replace it with this address space.

And in that spirit, let's just call it what it is: Provider Private
Address Space that they can use for whatever they want.  In fact, for
numbering local WAN connections inside a provider's space, this could
free up a very large amount of IP space in some providers.  In other
words, just let them use it for whatever they want to use it for with
the following conditions:

1.  An end user network should never use that space
2.  It should never be used for links between providers.
3.  It should never be used for links directly between end systems.

The problem with doing this is:

Providing a /10 and specifying a purpose for it globally is outside the
jurisdiction of ARIN.  Once the space is allocated, it is going to be
used globally, even outside of ARIN's jurisdiction.  ARIN has no control
over the use of that space outside of ARIN's jurisdiction.

Creating an address space for global use is probably the bailiwick of
the IETF.  Using it for NAT is probably not a good enough justification
for creating it but using it to free up large amounts of address space
used currently for general WAN links in addition to the NAT application
might be enough.

What is being proposed here is not really NAT444 middle 4 address space,
it is general "provider private IP space" that could be (and likely will
be) pressed into service in any number of ways.