[arin-ppml] End non-public IPv4 assignments?

Leo Bicknell bicknell at ufp.org
Mon Jan 24 09:28:24 EST 2011

In a message written on Sun, Jan 23, 2011 at 11:38:11PM -0500, William Herrin wrote:
> Let me reverse the question: in light of the situation on the ground
> today, is there anything you would view as a reasonable justification
> for an IPv4 allocation or assignment to a single entity which will not
> be routed on the public Internet? What?

I have run into a number of situations that make perfect sense.
I'll describe one.

Several companies in the financial services sector operate "exchanges".
To you and I these look just like an internet peering point, the
operator runs a layer 2 fabric where multiple parties connect.  The
one I have personal experience with had about 150 companies connected
last time I checked.  The companies are allowed to talk to each
other, the one I worked on was used for check clearing between

If you were to use 1918 space for this application it would require
coordination with 150+ entities to ensure no conflicts.  That's not
really practical.  Companies route the exchange some portion of the
way into their network (typically to their DMZ) and thus need space
that doesn't conflcit with their normal needs.  Gobally unique does
the job nicely.

This block though will never appear on the Internet you can reach
from your home DSL line.

I think it would be interesting for ARIN to provide some statistics,
but my gut tells me that the number of situations like this that
pass muster with the ARIN staff is small, so I think this is an
area that isn't even worth thinking about.

       Leo Bicknell - bicknell at ufp.org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/
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