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IPv4 Depletion – FAQ

Note: ARIN's IPv4 free pool has depleted as of 24 September 2015.

How Did ARIN Run Out Of IPv4 Addresses?

On 3 February 2011, the Internet Assigned Numbers Authority (IANA) issued the remaining five /8 address blocks in the global free pool equally to the five RIRs, and as such ARIN is no longer able to receive additional IPv4 resources from the IANA.

The ARIN community has worked together over the last several years in developing policy to manage how ARIN allocates and assigns IPv4 addresses. These efforts have extended the life of the IPv4 address pool in the ARIN region, but depletion of the IPv4 address pool is an impending reality. ARIN has reviewed and refined its procedures to create an IPv4 Countdown Plan explaining how IPv4 requests will be processed as the remaining IPv4 address pool is distributed.

What Does "Space Available" Really Mean And Why Does It Fluctuate?

"Available space" includes our current IPv4 inventory minus any returned, reclaimed, or revoked address blocks that may be in a hold status. This space fluctuates regularly based on new allocations and assignments being issued and incoming address space taken off its hold status. Please subscribe to the ARIN-issued mailing list to receive a daily report of address blocks returned and address blocks issued directly by ARIN or address blocks returned to ARIN's free pool. You may also refer to our Statistics page for historical stats and monthly updates.

Why are there differences between the IPv4 Inventory Counter and the ARIN-issued report?

The IPv4 inventory counter displayed on ARIN's homepage 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 being held by ARIN until it is clear to release 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.

The ARIN-issued report was never intended to track ARIN's current IPv4 inventory. The ARIN-issued report was created in response to ACSP Suggestion 2008.2 - Tracking Address Blacklists, beginning 2 January, 2009. This report reflects allocations/assignments made directly by ARIN to customers, or address blocks returned to ARIN's free pool.

Additionally, the ARIN-issued report now includes IP address space issued via 8.3 transfers from one organization to another, which are never included on ARIN's IPv4 inventory counter. In the case of an 8.3 transfer, IPv4 addresses are removed from the ARIN database from one organization's registration record and re-issued on that same day to another organization's registration record.

Note: Between the time ARIN approves an IPv4 allocation or assignment, and the point at which ARIN issues the address space to the customer, these addresses are placed on hold for up to 60 days pending payment and or Registration Services Agreement (RSA) and are removed from the IPv4 inventory counter. This will not however, be reflected on the ARIN-issued report.

Why is There a Difference Between ARIN's IPv4 Inventory Counter and Whois?

The removal of IPv4 address space from ARIN's inventory does not always coincide with the registration of that space being reflected in Whois. For example, when an IPv4 request has been approved by ARIN, the space is removed from ARIN's inventory immediately, but will not be reflected in Whois until the recipient organization has paid their registration fee and signed a Registration Services Agreement (RSA). During this 60-day holding period for any given IPv4 request, the Inventory counter and Whois will not reflect precisely equal information. Should ARIN not receive payment and a signed RSA by the end of the holding period, that address space will be returned to ARIN's inventory.

What Happens When ARIN Runs Out Of IPv4 Address Space?

It's inevitable that there will be some organizations that will still want/need IPv4 address space after the ARIN resource pool is depleted.

ARIN adopted a policy in 2010 in preparation for the day when it would be unable to fulfill qualified IPv4 requests.  This policy stipulates that ARIN establish a Waiting List for Unmet Requests.  The highlights of this policy text can be found below, however, ARIN encourages interested parties to review the full text, found in the Number Resource Policy Manual in Section 4.1.8.

We will consider IPv4 depleted when we have (one or many) customers on the Wait List for Unmet requests.  These customers will be qualified to receive IPv4 address blocks that are larger than we can fulfill.  These customers will have the option of going on the Wait List or receiving a smaller block size or pursuing an IPv4 Transfer.

You Told Me You Can't Fill My Request, But The Available Address Space Listed Is Larger Than What I Requested. What Is Going On?

The total IPv4 address space listed as available is shown in aggregate. Your request could not be filled because it is larger than any continuous address range that ARIN had available for allocation at that point in time. NRPM 4.1.8 stipulates that after IANA IPv4 depletion, ARIN will issue IPv4 address space in a "single, continuous range of addresses." This means you may request one single portion of address space (organizations can only request more IPv4 address space once every three months).

What if I don't want to go on the Wait List?

You do have the option of turning to the IPv4 Transfer Market, and you have a few options depending on whether or not you have located a source for the addresses you need.

We strongly encourage organizations seeking a transfer to get pre-approved in order to expedite the process. Pre-approval is available for both Transfers to Specified Recipients (NRPM 8.3) and for Inter-RIR Transfers (NRPM 8.4).

ARIN also offers a Specified Transfer Listing Service (STLS) to facilitate the transfer of IPv4 addresses.

I Thought There Was Reserved IPv4 Space?

You are correct, there is dedicated space that has been set aside. In accordance with NRPM 4.10, a contiguous IPv4 /10 block to facilitate IPv6 deployment, was reserved and removed from the remaining IPv4 address pool in 2011 when ARIN received its last /8 from IANA. This reserve pool will remain available to those who qualify per policy.

Does this impact my ability to get IPv6 address space?

We have plenty of IPv6 address space. You can request and get IPv6 address space from ARIN in accordance with the policies in the NRPM, just as you did prior to IANA IPv4 free pool depletion. ARIN largely considers your IPv4 and IPv6 holdings separate when reviewing requests. Some IPv6 policies do refer to IPv4 policies when describing points of criteria, however IPv4 depletion does not impact your ability to get IPv6 address space from ARIN.

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