8/3/2010 -- The international registries that allocate IP addresses say only about 6 percent of IPv4 addresses remain available, and with an uptick in demand since the beginning of the year, the pool could be exhausted in about six months.

"We continue to assign addresses globally" in the IPv4 space, said John Curran, president and chief executive officer of the American Registry for Internet Numbers (ARIN), the regional registry that covers North America and parts of the Caribbean. "We're getting to the point where when we look at the three-year trend, we would have about a year left before that pool goes to zero."

But if assignments are based on the rate of demand since the beginning of this year, addresses could be gone in half that time, he said.

With large service providers increasingly looking to the new generation of IPv6 addresses to support future offerings, there is increased urgency for making public-facing resources such as Web sites accessible through IPv6 networks.

"They need to begin planning aggressively" for making Web sites IPv6-accessible without using address translation, which could create bottlenecks for large enterprises, such as government agencies, Curran said.

The National Institute of Standards and Technology has published a profile for IPv6 capability for networking equipment that can be used for government acquisitions, and as of July, agencies can require from vendors a Supplier's Declaration of Conformity with the USGv6 profile in their networking equipment acquisitions.

The Internet protocols are a set of rules that define how devices communicate via packet-switched networks, such as the Internet. The numerical addresses that identify network entities are a part of the protocols. Because of the need to upgrade the protocols and expand the number of addresses available to accommodate a level of Internet use that was not originally anticipated, Version 4, which is the current IP version, is being replaced with Version 6.

Addresses are assigned to users in wholesale lots by the five Regional Internet Registries. In addition to ARIN, they are AfriNIC, which covers Africa; APNIC, covering the Asia-Pacific region; LACNIC, covering Latin America and the Caribbean; and RIPE NCC, covering Europe, the Middle East and parts of Central Asia.

U.S. government agencies have readied their backbones to handle IPv6 traffic, and the Office of Management and Budget directed NIST to develop standards and testing programs to support wide-scale adoption of IPv6 in government. In response, NIST has developed the USGv6 profile for hosts and routers and a specification for network security devices. Two independent laboratories have been accredited to certify that products meet the USGv6 profile: ICSA Labs, an independent division of Verizon Business, and the University of New Hampshire's Interoperability Laboratory.

The profile is a recommended acquisition guide and is not mandatory, but registries are working to raise awareness of the need to prepare for IPv6. The pool of remaining IPv4 addresses already is too small to accommodate some large deployments, such as sensor networks or smart-grid monitoring, Curran said.

"Some large organizations realize that using IPv4 won't give them the longevity they want, so they are beginning to look to IPv6," Curran said.

Because the government got into the Internet early, agencies typically have adequate reserves of IPv4 addresses for their own use. Their driver for adopting IPv6 is the need to keep resources available. Large networks being deployed for new services and devices soon will be using IPv6. IPv4 will continue to work for many years to come, but users from IPv6 networks will need to go through network translation devices to reach existing sites, which could cause traffic bottlenecks, or they will not be able to access native IPv4 resources.