[arin-ppml] Taking back UNUSED addresses.

Leo Bicknell bicknell at ufp.org
Fri Sep 12 14:44:09 EDT 2008

There's been a lot of speculation on the LRSA around the premise
that ARIN wants to "take back addresses".  While I have no doubt
that some people have that view, I don't think the vast majority
of people want to take back any addresses in active use.

One of the items that comes up is the question of how much fallow
space may be out there.  It would seem the skeptics think there is
very little fallow space, to which the "attack" must be on space
in use.  Here are some snippets (including how to get the full
report) from the CIDR report posted today to the NANOG mailing

> This is an automated weekly mailing describing the state of the Internet
> Routing Table as seen from APNIC's router in Japan.
> Daily listings are sent to bgp-stats at lists.apnic.net
> For historical data, please see http://thyme.apnic.net.
> If you have any comments please contact Philip Smith <pfs at cisco.com>.
> Routing Table Report   04:00 +10GMT Sat 13 Sep, 2008
> Report Website:     http://thyme.apnic.net
> Detailed Analysis:  http://thyme.apnic.net/current/
> Analysis Summary
> ----------------
> Number of addresses announced to Internet:                   1916473632
>     Equivalent to 114 /8s, 59 /16s and 17 /24s
>     Percentage of available address space announced:               51.7
>     Percentage of allocated address space announced:               62.8
>     Percentage of available address space allocated:               82.3
>     Percentage of address space in use by end-sites:               73.5
So globally around the world 19.5% (82.3 - 62.8) of all space that
has been allocated is not routed on the public Internet.
> ARIN Region Analysis Summary
> ----------------------------
> Number of ARIN addresses announced to Internet:               361286880
>     Equivalent to 21 /8s, 136 /16s and 204 /24s
>     Percentage of available ARIN address space announced:          74.3

In the ARIN region, 25.7% of all IP space that has been allocated is not
routed on the public Internet.

To be clear, this number will likely never be zero for a number of
legitmate reasons:

- Newly allocated space may take days/weeks/months to be actually
- Some space is used for semi-connected networks, or private networks
  that interconnect public players and thus will never appear on this
- Some people are in the process of moving from one provider to another
  and their space is unused for a brief period of time in the middle.

However, as we reach a point where there is no more free IPv4 space
to be given out, I suspect everyone is going to start to look at
that 25.7%.  Some fraction of that, perhaps a large fraction, is
likely not in use at all.  These range from situations where I think we
all agree space should be reclaimed:

- The person who requested it has died.
- The company was dissolved.
- The original requester has moved to PA space and no longer needs PI.

To situations where it is a bit murkier if reclamation is a good idea or

- Two companies, both with a /24 each and only using 20 IP's merge, and 
  end up using 40 IP's in a single /24, holding the other in "reserve".
- A company that previously justified a /16 has seen their customer base
  shrunk to 10% of what it was when they requested the /16.

In my opinion ARIN should be aggressively "going after" that 25.7%
of the space that isn't routed.  They should be documenting if it
is used on private networks, or if the contact is totally gone.  I
believe this needs to happen via multiple methods, not just one.
Most importantly, ARIN needs to be positioning itself for a future
where that 25.7% is under great scrutiny, as there is no more free
space and plenty of people who would like to use it if it is free.
I believe ARIN needs stronger relationships with address space users
to make that happen, which is why I am pushing for there to be
contracts and regular contact with legacy space holders.

This has implications for the LRSA discussion.  While I don't want
to take any space away from someone who is using it the contract
can't be so lopsided such as if someone really and truly isn't using
it they can keep it from the community forever.  It's a concept I
haven't seen discussed much.  I wonder if those who put forth the
view that the legacy assignment was made "forever, with no conditions"
would defend the right of the legacy holder to hold on to the
numbers and not use them.  Is holding the space in reserve, unused,
one of the "rights" of legacy holders?

It's fun to talk about the implications of contracts and policies
today, but with an available free pool there is little "threat" to
anyones use of IP space.  It's much more interesting, and useful,
to think about a world where there is no free pool.  The pressure
on people, legacy or not, who have space but are not using it at
all will be huge.  By the numbers that is ONE in FOUR of the people
who have received space in the ARIN region....

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