ARIN Issues Final IPv4 Addresses in Free Pool, Forcing Shift to IPv6

Internet's "exponential growth" depletes IPv4 addresses

David Hamilton

September 28, 2015

3 Min Read
ARIN Issues Final IPv4 Addresses in Free Pool, Forcing Shift to IPv6
(Photo by Michael Bocchieri/Getty Images)



This article originally appeared at The WHIR

With the explosion in the number of Internet-connected devices, the IPv4 address space used to identify networked devices has been quickly running out, making the transition to IPv6, which provides additional address space, inevitable.

This week, the American Registry for Internet Numbers (ARIN), the regional Internet registry for much of North America, has issued the final IPv4 addresses in its free pool, meaning that IPv4 has finally reached depletion.

At 128 bits, IPv6 has a much larger address space than the current standard, IPv4, which is facing the threat of address exhaustion because of its small size. IPv6 provides more than 340 trillion, trillion, trillion addresses, compared to the four billion IP addresses that are available with IPv4.

IPv6 also provides more flexibility in allocating addresses and routing traffic, eliminating the need for network address translation. Furthermore, with the coexistence of IPv4 and IPv6, gateway masking can add latency and could remove accurate geolocation and customer analytics data from IPv4.

With the first exhaustion of the ARIN IPv4 free pool, organizations will have to shift their attention to IPv6.

“The exhaustion of the free IPv4 pool was inevitable given the internet’s exponential growth,” ARIN president and CEO John Curran said in a statement. “While ARIN will continue to process IPv4 requests through its wait list and the existing transfer market, organizations should be prepared to help usher in the next phase of the internet by deploying IPv6 as soon as possible.”

Even though it has reached depletion, there will continue to be IPv4 address space issued to organizations by ARIN over the coming months.

Over the past few months, organizations qualifying for large block sizes were given the choice of joining the waiting list for unmet requests or accepting a smaller /24 block that was available. In the case they chose not to accept the /24 block, that block would go back into the inventory.

In the future, any IPv4 address space that ARIN receives from IANA, or recovers from revocations or returns from organizations may be used to satisfy approved requests on the waiting list for unmet requests. If ARIN is able to fully satisfy all of the requests on the waiting list, any remaining IPv4 addresses would be placed into the ARIN free pool of IPv4 addresses to satisfy future requests.

According to the latest statistics from Google, IPv6 is used in 21 percent of website connections in the US, but it’s still below nine percent globally. However, organizations have been aware of the need to deploy IPv6 for quite some time. In a 2010 survey, approximately 84 percent of organizations already had IPv6 addresses or have considered requesting them from their supplier.

Many hosting and infrastructure providers have also ensured their IPv6 compatibility over the past few years including Carpathia Hosting, Telehouse, Verio, SoftLayer,CoreLink, The Planet and NTT.

ARIN board chairman and Internet pioneer Vint Cerf said, “When we designed the Internet 40 years ago, we did some calculations and estimated that 4.3 billion terminations ought to be enough for an experiment. Well, the experiment escaped the lab… It needs room to grow and that can only be achieved through the deployment ofIPv6 address space.”

This first ran at

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