Internet Addresses Rapidly Running Out

The Number Resource Organization (NRO), which oversees global allocation of IP addresses, announced this week that less than 10 percent of the available IPv4 address space remains unallocated.

"This is a key milestone in the growth and development of the global Internet," said NRO chairman Axel Pawlik. "It is vital that the Internet community take considered and determined action to ensure the global adoption of IPv6," the next-generation of Internet protocols.

The protocols are rules defining how devices communicate over networks such as the Internet, and the numerical addresses that identify network entities are a part of them. Without the availability of addresses afforded by IPv6, the world would run out of addresses, Pawlik said.

The NRO is the international representative of the five Regional Internet Registries that allocate addresses. Those registries are AfriNIC, which covers Africa; APNIC, which covers Asia Pacific; LACNIC, which covers Latin America and the Caribbean; RIPE NCC, which covers Europe, the Middle East and parts of Central Asia; and ARIN, which covers North America and parts of the Caribbean.

The remaining pool of IPv4 addresses is expected to run out in less than two years. As of Jan. 20, the estimated time remaining was 592 days, said ARIN president John Curran.

Depletion of IPv4 addresses does not mean that the allocated addresses cannot be used or that the Internet will stop working. But it could put constraints on Internet growth and connectivity.

"We're down to the final 10 percent, and when we run out, the Internet carriers will not be able to add customers without going through translation gateways" that will connect new IPv6 addresses with older infrastructure using IPv4, Curran said. "Those gateways are going to slow down the Internet."

To avoid bottlenecks and make resources globally available, Web sites need to enable use of the new protocols. The U.S. government has mandated that its core networks be able to accommodate IPv6 traffic, but to date there has been no requirement that the protocols be enabled on servers and Web sites. The government does intend to actively deploy IPv6, however, and in May the Federal CIO Council released a document called "Planning Guide/Roadmap Toward IPv6 Adoption in the U.S. Government."

The roadmap, created by the CIO Council's IPv6 Working Group and the private sector, provides direction, and is incorporated into version 3 of the Federal Enterprise Architecture Assessment Framework. It recommends that agencies:

  • Use their enterprise architecture and capital planning activities to plan for the deployment of IPv6-enabled network services; show how they intend to use these services to power IPv6-enabled applications; commit to specific, measurable improvements in agency performance; and reflect the same in their investment proposals.

  • Leverage the guidance and common milestones provided in this document to develop an effective transition plan.

  • Set up test laboratories and/or prototype networks to acquire IPv6 experience and expertise.

  • Deploy secure IPv6-enabled network services, as appropriate, during regular technology upgrade cycles.

Because of the increased complexity of managing and securing networks that use IPv6 as well as IPv4, it is important that organizations begin enabling the new protocols and gaining experience now, Curran said.

IPv4 addresses have been in use for more than 30 years, and are able to accommodate about 4 billion addressed devices. But during the late 1970s and early 1980s, there were only 26 sites on the old ARPAnet, precursor to the Internet, Curran said. The number grew to around 300 in the late 1980s, and to the thousands in the early 1990s.

"Over the last 20 years, the vast majority of the addresses have been assigned," he said. "Ninety percent are gone now, and the rate at which we are allocating addresses is increasing" as more people gain access, connectivity is extended into rural and developing areas, and as the number of devices used by each individual grows.

Not all of the allocated IPv4 addresses are being actively used, and some could be recovered for re-allocation.

"We might be able to get another 5 percent back," Curran said. "Maybe more. But it's not much. We might have another year" with reclamation. "But in the end, you're still going to have to deploy IPv6."

About the Author

William Jackson is the senior writer for Government Computer News (

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