[arin-ppml] Draft Policy 2009-2: Depleted IPv4 reserves

Matthew Wilder Matthew.Wilder at telus.com
Mon Mar 23 17:30:27 EDT 2009

I think there is definitely a place for a policy somehow limiting the size of allocations when there is less than 6 months to go in projected ARIN IP Address reserves.  I think a maximum allocation size of /20 is going to be too limiting for large ISPs (full disclosure, I work for TELUS, a large Canadian ISP).  This policy is unusually biased against the largest consumers of IP addresses.  I may have read the policy proposal wrong, but it also looked like a /20 is the most an organization will get in a 6 month period.  That would be even more limiting.

(NOTE: if you get tired of reading this long-winded feedback, skip to my suggestion)

*******My feedback:*******
Using the statistics page, it can be seen that the vast majority of IP Address space in 2006 and 2007 went to 24 organizations.  Among other factors, I would suggest that the reason this is actually good is that large ISPs can efficiently utilize IP Addresses in the way IP address space is given to end users (including DHCP).

Last year, someone used a gas station analogy to depict the system that ARIN and ISPs and EUs constitute.  ARIN (the gas station) controls the IP Addresses (the fuel) which are distributed to those (ISPs and EUs) in need of IP addresses (fuel).  Using this analogy, I recall someone making a statement that all the people with civics will be totally left out when the bug SUVs (large ISPs) are sucking up the last of the fuel.  That analogy is off the mark first of all because large ISPs probably utilize IP Address space more efficiently than the average ISP or EU, where SUVs, well, they aren't the model of efficiency.  The second way this analogy is a bit misleading is that it represents SUVs as coming in at the last minute to take all of what is left, when the SUVs are only one of many consumers of IP Address space.

Again considering the statistics page, over 80% of address allocations in 2006 and 2007 went to 24 organizations, roughly 1% of the organizations.  So these would not be the organizations coming out of nowhere to take what is left of the unallocated IPv4 space.  I imagine that the other thousands of organization covered by ARIN would be the ones who might come up to ARIN in 2011 or 2012 and load up on their last block of IPv4 space, which may last them 6 years, let alone 6 months.

On the other hand, large ISPs who are the most consistent consumers of IP Addresses would be told to accept a block of IP Addresses that will last them 6 weeks, maybe even 6 days.

*******My suggestion:*******
I think this policy has its place.  I think the limit should focus not on a particular subnet size, but on the historical allocations to an organization and the projected utilization of the block being requested.  The allocation should target satisfaction of 3 months of the ISP's requirement.  For example, an organization that usually consumes space totalling a /15 every year should be granted a /17 which will probably last for 3 months of projected requirements.  This is certainly a little harder to put into writing, but I think it offers greater fairness.

Thanks for reading!

Matthew Wilder

-----Original Message-----
From: arin-ppml-bounces at arin.net [mailto:arin-ppml-bounces at arin.net] On Behalf Of Member Services
Sent: Monday, March 23, 2009 12:06 PM
To: arin-ppml at arin.net
Subject: [arin-ppml] Draft Policy 2009-2: Depleted IPv4 reserves

Draft Policy 2009-2
Depleted IPv4 reserves

The following draft policy text is being posted for feedback and discussion on the Public Policy Mailing List (PPML).

This draft policy was developed by the ARIN Advisory Council (AC) from Policy Proposal 81: Depleted IPv4 reserves. The AC has taken the proposal and developed it into a draft policy. The AC was required to submit text to ARIN for staff and legal assessment prior to selecting it as a draft policy. The assessment, along with the text that was assessed, is located below the draft policy.

On 20 March 2009 the ARIN Advisory Council (AC) selected Draft Policy
2009-2: Depleted IPv4 reserves for adoption discussion on the PPML and at the upcoming Public Policy Meeting.

Draft Policy 2009-2 is below and can be found at:

We encourage you to discuss Draft Policy 2009-2 on the PPML prior to the ARIN XXIII Public Policy Meeting. Both the discussion on the PPML and at the Public Policy Meeting will be used by the AC to determine the community consensus regarding adopting this as policy.

The ARIN Policy Development Process can be found at:

All of the Draft Policies under discussion can be found at:


Member Services
American Registry for Internet Numbers (ARIN)

## * ##

Draft Policy 2009-2
Depleted IPv4 reserves

Date: 23 March 2009

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. This restriction will be lifted in the event the reserve of unallocated IPv4 address space increases to an equivalent /7.


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 IPv6.

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 ISPs 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


ARIN Staff Assessment

*Title: Depleted IPv4 Reserves*

*Proposal Submitted: 02 Dec 2008*

*Revision Submitted: 16 Feb 2009*

*Date of Assessment: 10 March 2009*

I. Understanding of the Policy:

*Staff Understanding of the Proposal:*

ARIN understands this policy goes into effect when ARIN has less than a
/9 worth of IPv4 address space available to be issued to customers. At that time, an ISP or End user can only receive a /20 from ARIN within a six month period. This restriction will be removed if ARIN's available pool of addresses increases to a /7 equivalent.

II. Comments:

A. ARIN Staff Comments:

          o One question to consider is whether staff should be setting
            aside a /9 in anticipation of this policy. If that is not
            done, there is the potential that one large request could
            take away a very large block of ARIN's remaining inventory
            and leave us with far less than the /9 equivalent needed to
            implement this policy. For example, if there is one /8 left,
            and ISP A qualifies for a /8, and it gets issued, then there
            will be no address space left to issue under this policy.
                + If the intent is to make sure there is at least a /9
                  available to give out in /20 blocks, then the trigger
                  point may need to be reconsidered. Here are two
                  potential options:
                      # Trigger the policy when filling a request would
                        drop the supply below a /9
                      # Give the org whose request would drop the supply
                        below a /9 as many addresses as would take us to
                        a /9, then trigger the policy.

B. ARIN General Counsel Comments:

The policy does not pose any significant legal risk to ARIN. A community decision to segment the remaining unissued IPV4 numbers to serve a larger number of users on its face does not discriminate against or for any user, large or small. Therefore it is legally unobjectionable. It is a rational scheme for distribution reasonably related to meeting the needs of as many end users as possible. Counsel respectfully suggests that the policy as drafted may contain potential seeds of confusion by providing for switching back to current distribution policies, and then back to this policy.

III. Resource Impact

The resource impact of implementing this policy is viewed as minimal. It is estimated that this policy could require up to 3 person months of effort to implement following ratification by the ARIN Board of Trustees. Because this implementation is not planned, it may preempt ARIN's current project deployment schedule. It may require the following:

    * Guidelines Changes
    * Modifications to existing registration software tools - they need
      to be able to report to staff existing inventory levels and to
      notify us when the /9 threshold is reached or is imminent.

Text assessed:

Depleted IPv4 reserves

*Policy statement:*

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. This restriction will be lifted in the event the reserve of unallocated IPv4 address space increases to an equivalent /7.

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