IPv6, the long-awaited upgrade to the Internet's main communications protocol, may be showing signs of life with Tuesday's announcement of MCI's first commercial customer for IPv6 services.

Cray, the supercomputing giant from Seattle, is the first U.S. company to admit to using MCI's IPv6 overlay service. MCI says it has a handful of other U.S. corporate and government clients for its IPv6 overlay service, which the top-tier ISP quietly made available in January.

"We're seeing quite a bit of demand spanning a number of different industries," says Kevin Gatesman, senior manager of emerging technologies for MCI.

"We've had a number of customers approach us directly and say: What can you do for me with IPv6? These are all big, readily recognised brand names like Cray. They're all at the leading-edge in their industries."

IPv6 is an upgrade to IPv4, the Internet's main communications protocol. Developed by the IETF, IPv6 promises easier administration, tighter security and an enhanced addressing scheme over IPv4.

Despite its promise, IPv6 has failed to catch on in the U.S. Until now, only one ISP - NTT Verio - offered commercial IPv6 service here.

MCI is offering a free IPv6 overlay service that can be used by any customer of its dedicated Internet access services in the U.S., Europe and Asia. MCI says it will offer native IPv6 services later this year.

"By the end of the year we will be offering native IPv6 services to customers with T-1 and T-3 service. They can run IPv4 or IPv6 on that facility," Gatesman says.

MCI admits that getting native IPv6 service ready requires many changes to its systems and services.

"It's a pretty big effort considering the sheer size of our IP service and the size of our backbone," Gatesman says. "As we do technology refreshes throughout our network, we make sure everything is IPv6 ready."

Gatesman says a U.S. Department of Defense mandate to migrate to IPv6 has caught the attention of network executives in other industries.

"The Defense Department mandate has driven a lot of folks to look at IPv6 seriously," Gatesman explains. "Of course, the government contractor types are interested. But we're also seeing interest from other areas like manufacturing, financial services and the wireless industry. We see folks looking at IPv6 for mobility, to put an IP address on every vehicle in a fleet, and for making the battlefield network-aware."

Cray is using MCI's IPv6 service for interoperability testing and development of next-generation software and applications for the Cray X1 Supercomputer product line. Cray has many customers working on military science and engineering projects, and these customers need IPv6 support. Cray is a long-standing customer of MCI.

"Cray is experiencing an increasing demand from the U.S. government and our Asia Pacific customers for hardware, software and applications that are IPv6 complaint," said Darren Dehnke, network engineer at Cray, in a statement. "Our customers are making long-term investments in their network infrastructure so it is critical that Cray supercomputers have the capability to evolve with IP technology."

MCI has been working on IPv6 services for select government and academia customers since 1998, but it's only this year that the company says it has seen real demand from U.S. companies.

"IPv6 has been on our roadmap for awhile, but we realized that this is something that's going to happen," Gatesman says. "Either we lead or we follow. And we've chosen to lead."

The North American IPv6 Task Force applauded the announcement of MCI's new IPv6 service. "It will help the adoption of IPv6 within the North American geography," says Jim Bound, task force chair and CTO of the IPv6 Forum. "Having ISPs support IPv6 also will help the evolution here to next generation networks, which will require the enablement of IPv6."