ICANN Assigns Its Last IPv4 Addresses

The Internet Assigned Numbers Authority (IANA) has handed out its last IPv4 addresses, leaving the remaining blocks to regional registries that in some cases may exhaust them within a few months.

The end of IPv4 (Internet Protocol version 4) addresses was announced in a ceremony in Miami on Thursday morning. Each of the five Regional Internet Registries (RIRs) was allocated one of the final five large blocks of about 16 million addresses.

The end of the central supply of IPv4 addresses signaled the urgency of enterprises and service providers to migrate to IPv6, the latest version of the protocol, which has been available for more than a decade and allows for an almost unlimited number of addresses. When there are no more IPv4 addresses available from the RIRs, new hosts on the Internet will not be able to communicate with systems that use only IPv4 without special mechanisms that could degrade the Internet experience. Some experts advise adopting a "dual-stack" approach to remain connected with both IPv4 and IPv6 hosts.

"A pool of more than four billion Internet addresses has just been emptied this morning," said Rod Beckstrom, president and CEO of the Internet Corporation for Assigned Names and Numbers (ICANN), which oversees IANA. "The future of the Internet, and the innovation it fosters, lies with IPv6."

IANA and the RIRs had laid the groundwork for Thursday's action in advance by agreeing on a policy that when the supply of large blocks went down to five, one would be assigned to each of the regional bodies. The policy was designed to ensure that regions where addresses were being used up less quickly wouldn't be left out in the end.

The Asia-Pacific Network Information Centre (APNIC) was assigned two large blocks of addresses earlier this week, causing the rule to kick in.

Though there is wide agreement that enterprises and ISPs need to migrate to IPv6, there are potential hazards both in delaying that move and in carrying it out. A key concern is that most available security tools don't work with IPv6. And though some experts point to network-based translation between the protocols as a short-term solution, others say that approach could break some applications and services.

The supply of fresh IPv4 addresses for North America will probably last only three to nine months, according to John Curran, president and CEO of the American Registry for Internet Numbers (ARIN), the region's RIR.

The action taken Thursday will have ripple effects on organizations that need IPv4 addresses in many countries.

As the final allocation took place, new rules immediately went into effect at the American Registry for Internet Numbers, the RIR for North America. In the past, ARIN has allowed its customers to forecast their need for addresses over the next 12 months and apply for a year's allocation. Now they will have to apply every 90 days, showing a forecast for that period.

"We don't want to have a circumstance where organizations come in and we give one a year's worth, and someone else has none," Curran said.

When APNIC's supply is reduced to its final block of 16 million addresses, it will restrict its customers to just one much smaller block of addresses. It expects this supply to last approximately five years.

Stephen Lawson covers mobile, storage and networking technologies for The IDG News Service. Follow Stephen on Twitter at @sdlawsonmedia. Stephen's e-mail address is stephen_lawson@idg.com