The fast growth also exposed how much of a burden the workaround is that's typically used to squeeze more devices onto the limited number of IPv4 addresses available: NAT (network address translation), which reuses IPv4 addresses across multiple devices within a local network, using smart routers to juggle which traffic goes where.

In the U.S., the relatively high number of IPv4 addresses still available and the widespread use of NAT has made IPv6 a “why bother?” project for most companies, Gomi said, even though most computers, operating systems, and network hardware built in the last four years support IPv6.

Despite that complacency, Gomi said, a range of emerging applications around security, mobility and collaboration will help push more U.S. companies to update their infrastructure and delve further into IPv6. As a provider of IPv6-enabled WAN circuits, NTT America hopes to cash in on that expected uptake. Its parent company NTT began migrating to IPv6 in 2001, and now supports both protocols worldwide.

U.S. companies risk losing the competitive edge that IPv6-based applications could provide their foreign competitors, said Yurie Rich, vice president at IPv6 Integration Services and Command Information, which specializes in transition services and application development. For example, if Toyota Motor were to develop a system that communicated information about needed services or product recalls directly to its vehicles, and General Motors did not, the U.S.-based company could lose out on subsequent sales.

"IPv6 isn't super sexy, it's plumbing or railroad tracks — but you need it if you want to build a bullet train," Rich said.

The opportunity for Internet-connected sensors
One of the biggest opportunities, NTT’s Gomi said, will be for companies to create new applications based on an increased ability to connect distributed sensor technologies directly to the Internet over IPv6 networks.

For example, in Japan, NTT helped build a new earthquake-monitoring network that promises to communicate warnings to metropolitan areas faster than previous systems. The extra speed comes from eliminating the latency caused by NAT. "Without NAT, there will be far less latency and hassle, and it will also be cheaper to build these types of systems," he said.

Earthquake monitoring is just one example of such Internet-connected sensor applications, Gomi said. He expects a wide range of uses, including security, collaboration, and mobility. "The killer applications will likely be sensor networking applications where companies want to put a lot of sensors throughout distributed locations," Gomi said.

The opportunities around collaboration and mobile                        
Another area where Gomi believes U.S. companies and end-users will find significant benefits in moving to IPv6 is in making it easier for mobile devices to connect to the Internet, again due to eliminating NAT’s latency and complexity overhead. He said IPv6 will benefit security for systems management of mobile devices and create opportunities for peer-to-peer applications. Because each device will have its own unique IP address, identity is easier to verify and location easier to determine.

At Cisco, Bracco sees similar advantages. His company's primary focus around IPv6 development is in the area of collaboration. Whereas IPv4 technologies typically requires application-level gateways to the Internet, the capability in IPv6 to assign unique IP addresses to larger numbers and varieties of devices will open up a "whole new world" of communications tools, he said.

Bracco also said the multicasting capabilities in IPv6 — sending one message to multiple recipients, rather than a separate copy for each —will drive a set of groundbreaking collaboration tools. "I see opportunities for collaboration from anywhere on a handheld device on the fly, and applications like video wherever you are," Bracco he. "Being able to be a road warrior of one, with access to collaborative tools without having to go through NAT will make you more effective in business."

The feds have led the way to IPv6 — and its benefits
The U.S. government saw the potential of IPv6 early, culminating in the August 2005 mandate that all agencies convert to it by June 30, 2008. Of the U.S. agencies, the Department of Defense has led the pack on the path to IPv6.

The DoD sees immediate benefits form adopting IPv6 throughout the military and intelligence communities and so made the IPv6 move quickly.

"IPv6 enables network ubiquity by allowing everything to be addressable. It makes it easier to pool information anytime anywhere, as long as people have clearance," said Kris Strance, senior IT analyst at the Office of the Assistant Secretary of Defense for Networks and Information Integration. "With IPv6-based sensor networks, we will have new ability for devices to report directly back to a central location. That is a huge advantage for us, particularly in tactical environments. Large-scale networks that use NAT cannot do that today."

For example, in Iraq, vehicles traveling in the theater of operations today must traverse among different networks, forcing constant reconfiguration of their communications systems, which involves a lot of legwork and administration, Strance said. But by using IPv6 applications — already being tested at the Naval Post-Graduate School in Monterey, Calif. — Humvees, tanks, ships, and airplanes will be able to operate in an "always-connected" manner.

Coordinating more effectively with central commanders and other forces in the field will ultimately improve the soldier's ability to carry out their orders, and may even save lives, Strance said.