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IPv4 IANA Free Pool Depletion – FAQ

A Note About Our /8 Inventory Counter

The counter on the homepage shows the number of /8s remaining. The numbers after the decimal point are equivalent to a percentage (so 5.22 /8s is 5 /8s + 22% of a 6th /8). There are some days and even weeks where the total reported on the website won't change very much (if at all). Why? Because the threshold we need to cross is pretty significant. 1% of a /8 is more than 2.5 /16s worth of space. That's a lot of space to give out, and there will be some stretches of days or even weeks where ARIN does not give out 2.5 /16s worth of addresses.

Please be advised that the counter is for informational purposes only and is provided as-is. We strive to keep the information up-to-date and update the counter once a day. You however should not rely on the counter when making decisions on the timing of your requests for space. We suggest that if you require space that you submit your request as soon as possible.

The Internet Assigned Numbers Authority (IANA) recently issued two blocks of IPv4 address space to APNIC, the Regional Internet Registry (RIR) for the Asia Pacific region. This allocation triggers a global policy that requires IANA to issue the remaining five /8 address blocks equally to the five RIRs. This allocation triggered a global policy that required IANA to issue the remaining five /8 address blocks equally to the five RIRs. This allocation was made 3 February 2011, and as such ARIN will no longer be able to receive additional IPv4 resources from the IANA. This could change in the future if a global address policy were to be implemented that enabled IANA to accept returned IPv4 addresses from the RIRs in increments smaller than a /8. ARIN will continue to issue IPv4 addresses in accordance with policy until the ARIN IPv4 resource pool is depleted. Please read the following FAQ for more information on what this means for ARIN customers.

Can I still get IPv4 address space from ARIN?

Yes, ARIN still has available IPv4 address space. We have developed an information sheet that explains the steps leading up to full depletion of the IPv4 address space. We cannot predict how long ARIN’s pool of IPv4 address space will last, but we will continue to distribute IPv4 address space in accordance with the policies documented in the Number Resource Policy Manual.

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 outgoing new allocations and assignments, and incoming address space taken off its hold status. Please subscribe to the ARIN-issued mailing list to receive a daily report of addresses returned and addresses issued directly by ARIN or address blocks returned to ARIN's free pool and refer to our Statistics page for historical stats and monthly updates.

Why is some address space being “held” and how long will you hold it?

ARIN holds all returned, revoked, and reclaimed address space for a minimum of six months.

  • Returned addresses are those that the registrant voluntarily returns to ARIN
  • Revoked addresses are those that ARIN takes back due to non-payment of registration fees
  • Reclaimed addresses are those that ARIN takes back due to fraud, misappropriation, or business dissolution

During the hold period, the resources are deregistered in Whois. Resources are held for at least six months to allow them time to clear any filters, or to allow an organization with revoked resources ample time to pay its overdue fees. Once we have held a block of IP addresses for at least six months, verified the IP addresses are unrouted, and contacted any blocklist operators to notify them of their stale listing, we make the block available for reissue.  ARIN may also have these address blocks bogon tested by an external third party during this hold period. Bogon testing is the process of probing networks to see if they will accept route announcements from the IP address range being tested.

Will ARIN now attempt to recover unused IPv4 address space, particularly the legacy space that is not being routed?

Even the successful return of more /8s would not significantly increase the lifetime for IPv4. Despite the small gains, the RIRs continue working on these issues and exploring all possible actions in this area.

Does IANA depletion change ARIN Internet number resource allocation policies?

IANA depletion triggers or impacts several policies:

    • Triggers NRPM 4.1.8, which limits requests to a single prefix once every three months while supplies last. This policy also establishes the rules for a waiting list. This is in case organizations want to wait for a larger allocation than ARIN is able to make at that point in time.
    • Impacts NRPM 4.2.4.4, which reduces the amount of address space that ISPs can request from a twelve-month to a three-month supply.
    • Impacts NRPM 4.10, which sets aside a contiguous IPv4 /10 block to facilitate IPv6 deployment.

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’s Specified Transfer Listing Service (STLS) provides a way for organizations to either advertise their available IPv4 address space or contact an organization with space to arrange a transfer using section 8.3 of ARIN’s NRPM. Similarly, if organizations have or are in need of IPv4 address space and have contacted an organization with reciprocal inventory or need, they are welcome to conduct a transfer under section 8.3 of ARIN’s NRPM without utilizing the STLS.

Per NRPM 4.1.8, if ARIN does not have sufficient inventory to fulfill a qualified IPv4 request, the requesting organization may choose to be placed on a waiting list of pre-qualified recipients. This waiting list will specify both the largest block the organization is approved to receive and the smallest block the organization will accept. As address blocks become available for allocation, ARIN will fulfill waiting list requests on a first-come, first-served basis, subject to block size availability and re-verification of an organization's eligibility.

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 return and request more once every three months).

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.

What is the status of the Interop /8?

ARIN accepted Interop's returned space in October 2010 and will not reissue it for at least six months, per existing operational procedure. After the hold period, it will become available for distribution (or possibly be returned to the IANA, depending on the global policy in effect at that time).