IPv4 Depletion Status at ARIN [Archived]

By Leslie Nobile

What happens after ARIN depletes its free pool of IPv4 address space?  Will there be a Phase 5 added to the IPv4 Countdown Plan? Is the IPv4 inventory counter always accurate?  These are just some of the questions we’ve been hearing in recent weeks. We understand that IPv4 depletion is causing confusion and uncertainty, so we’d like to try address some of these common questions and provide some additional information on the current status of IPv4 address space at ARIN.

Update on the IPv4 Countdown Plan

ARIN moved into the final stage (Phase 4) of its documented IPv4 Countdown Plan in April 2014. ARIN’s IPv4 countdown plan was designed to have only 4 stages, which means that we will continue working in Phase 4 as we move toward full depletion of ARIN’s available IPv4 inventory.  ARIN will not be adding a Phase 5 but will continue in Phase 4 when IPv4 needs will be met through IPv4 address transfers and the IPv4 waiting list.

You can find more detail on the Countdown Plan on our website and in some earlier blog posts (dated April and October 2014). In Phase 4, all IPv4 requests are processed in the order they are received and are team-reviewed by ARIN’s resource analysts. While team review has slowed down overall processing times, we are working diligently to streamline the process and maintain our standard two-day response time on all IPv4 request tickets.

Although you might have expected to see a rapid increase in IPv4 requests, or a “run on the bank” once we hit our last /8, IPv4 resource traffic has actually remained fairly steady since that time.  We did see a slight increase in April 2014 after we announced that we had reached Phase 4 of the Countdown Plan, but other than that, things have been fairly consistent.

The IPv4 Counter

The IPv4 inventory counter displayed on ARIN’s homepage (see it on the bottom right at www.arin.net), was designed to provide the community with a daily snapshot of how much IPv4 address space ARIN has left in its available pool. The counter shows the total number of /8 equivalents remaining in ARIN’s available IPv4 inventory as well as a list of the total number of prefixes available of any given size.  “Available space” includes our current IPv4 inventory minus any returned, reclaimed, or revoked address blocks that may be in a hold status.  Hold status is a term that describes address space held by ARIN until it clears any filters before being released back into ARIN’s IPv4 free pool. The “Available space” as reflected in the IPv4 counter fluctuates regularly based on new allocations and assignments being issued, and incoming address space being taken off its hold status.

If you use our daily ARIN-issued mailing list to help you keep track of how much IPv4 address remains in ARIN’s inventory, you will find that it does not match the IPv4 inventory counter on our homepage. In fact, you will likely find several discrepancies between the ARIN-issued report and the IPv4 inventory counter.

The ARIN-issued mailing list provides a daily report of IPv4 and IPv6 address space returned to ARIN’s available inventory and IPv4 and IPv6 address space issued directly by ARIN to its customers. The data reported in the ARIN-issued report also includes IPv4 address space issued via 8.3 transfer which is NOT included in the IPv4 counter.  Additionally, once ARIN approves an IPv4 address block, it is immediately removed from the available inventory and placed on hold until registration fees have been paid and a Registration Services Agreement has been signed.  These resources will not show up in the available inventory, nor will they show up on the ARIN-issued report until all administrative tasks have been completed.

As we watch the IPv4 counter continue to drop, ARIN will strive to keep things running as smoothly as possible.  IPv4 depletion comes as no surprise, and as we reach these final stages, we will continue to conduct “business as usual” and provide our customers with the best possible service we can. And in the face of ultimate IPv4 depletion, we will continue to encourage all ARIN customers to get their IPv6 address space to ensure the future growth of their networks. There is plenty for everyone!