[arin-ppml] Policy Proposal: Depleted IPv4 reserves

Member Services info at arin.net
Tue Dec 2 14:53:23 EST 2008

ARIN received the following policy proposal. In accordance with the ARIN
Internet Resource Policy Evaluation Process, the proposal is being
posted to the ARIN Public Policy Mailing List (PPML) and being placed on
ARIN's website.

The ARIN Advisory Council (AC) will review this proposal at their next
regularly scheduled meeting. The AC will assign shepherds in the near
future. ARIN will provide the names of the shepherds to the community
via the PPML.

In the meantime, the AC invites everyone to comment on this proposal on
the PPML, particularly their support or non-support and the reasoning
behind their opinion. Such participation contributes to a thorough
vetting and provides important guidance to the AC in their deliberations.

The ARIN Internet Resource Policy Evaluation Process can be found at:

Mailing list subscription information can be found at:


Member Services
American Registry for Internet Numbers (ARIN)

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Policy Proposal Name: Depleted IPv4 reserves

Author:  Dan Alexander

Proposal Version: 1

Submission Date: 12/2/2008

Proposal type: New

Policy term: Permanent

Policy statement:

(add the following section to the nrpm)

4.1.8 Depleted IPv4 reserves

A limit will be applied to all IPv4 address requests when ARIN's reserve
of unallocated IPv4 address space drops below an equivalent /9. When
this happens, an ISP or End User may receive up to a single /20 within a
six month period.


As the reserve of IPv4 address space becomes smaller, there is a risk
that many organizations will be denied resources by a large, last minute
request. By implementing a throttle on the last of the IPv4 address
space, a more limited group of organizations will be impacted, allowing
many organizations to receive ongoing resources during the transition to

According to the ARIN statistics page
http://www.arin.net/statistics/index.html, 1,993 organizations were
issued IP space in 2006 and 2007. Of these allocations 41% of the
applicants received less than a /20. On the opposite end, 82
organizations received large blocks. Given that the last reserve of IPv4
space cannot possibly meet the needs of the 82 organizations, the space
could be managed in a way to provide for the needs of a wider base of
consumers while the largest ISP's build momentum behind IPv6.

The goal is to find a balance between the needs of organizations
requiring space, and avoiding the restrictions on end user growth. For
this reason, any caps on allocations should be implemented when the
reserves are essentially depleted, rather than trying to restrict end
user growth when IP space is still readily available.

By putting a six month window on the maximum allocation, the remaining
IP space could provide at least one year for everyone to implement other
solutions while still being able to obtain an IPv4 address allocation.
The time period was also added to provide a consistent rate of
depletion, avoiding a scenario where a large organization could queue
multiple, justifiable requests, resulting in the scenario the proposal
is intended to avoid.

Additional language may need to be added in the event a paid transfer
policy is approved. The thinking is to have two pools of available IP.
One being the current IANA allocated, reserve of IP space. The second
being IP blocks recovered through monetary incentive. This proposal
would apply to the IANA allocated reserves and would not apply to blocks
made available by monetary means.

An additional thought was to avoid tying this policy shift specifically
to the last /8 allocated by IANA. This allows the policy to come in and
out of play in the event that IPv4 address space is abandoned or
returned to ARIN.

Timetable for implementation: Immediate

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