​North America's IPv4 address supply runs dry

The long-predicted exhaustion of IPv4 addresses has now taken place in North America, with the region's authority left with no further supply of the 32-bit labels to issue.

​The last seconds are ticking off the U.S. IPv4 network clock

ARIN reports it only has about two to four weeks of IPv4 Internet address blocks left.

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For the first time, the body responsible for allocating IP addresses in North America says its free pool of IPv4 numerical labels is exhausted.

The American Registry for Internet Numbers, or ARIN, yesterday issued the final free-pool 32-bit IP addresses, essential for identifying and locating devices on the internet.

In the early days of the internet, the 4.3 billion possible IPv4 addresses appeared adequate. But as early as 1995 the Internet Engineering Task Force, or IETF, named the IPv6 successor protocol, and people have been warning of the consequences of the impending IPv4 address exhaustion for years.

Because the pool is exhausted, there will be no further routine IPv4-address allocation to individuals or businesses and service providers in the region.

"Due to depletion of its IPv4 Free Pool, ARIN is no longer able to fulfil requests for IPv4 address space, unless you are an organization requesting a small block of IPv4 address space to facilitate the transition to IPv6 or micro-allocations for specific purposes such as the operation of exchange points," ARIN said in a statement.

ARIN, which manages internet addresses for the US, Canada, and most Caribbean countries, is advocating that businesses instead take up 128-bit IPv6 addresses.

"To ensure the growth of your network well into the future, you might also consider requesting IPv6 address space directly from ARIN," the non-profit body said.

President and CEO John Curran said in the future, any IPv4 address space that ARIN receives from the Internet Assigned Numbers Authority, or IANA, which oversees global IP address allocation, or that ARIN recovers from revocations or returns, will be used to satisfy approved requests on its waiting list for unmet requests.

"If we are 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," he said.

IANA's primary pool of IPv4 addresses was exhausted in February 2011.

As well as going on the ARIN waiting list, businesses can identify another company that is prepared to transfer some of its IPv4 address space. Alternatively, firms seeking IPv4 addresses can sign up with ARIN to find a willing participant.

"Effective today, because exhaustion of the ARIN IPv4 free pool has occurred for the first time, there is no longer a restriction on how often organizations may request transfers to specified recipients," Curran said.

More on IPv4 and IPv6


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