ISP Verio, a subsidiary of NTT, is rolling out IPv6 support to U.S. customers in a move the company says will offer more flexibility for current and future network needs.

The native-mode IPv6 service will let users that have upgraded to IPv6 internally take those capabilities to their WANs. IPv6 tunneling lets users maintain standard IPv4 WAN connectivity but test IPv6 addressing and support on small network segments, says Stan Barber, vice president of engineering operations for Verio's broadband business unit.

"It's not the zippiest service because it's riding inside IPv4, but it will have a good price-point that will let users put their toe in the water," Barber says.

IPv6 is the newest IETF IP specification. Although ratified in 2000, it has not been widely deployed by users or carriers in the U.S.

Benefits touted with IPv6 include the ability to support many more IP addresses and auto-configure addressing on a network.

IPv6 has a 128-bit address space compared with IPv4's 32-bit space, which exponentially increases the number of addresses an IPv6 network can support. IPv6 also eliminates the need to configure IP addresses on a network manually. This version of the protocol lets a host machine automatically configure IP addresses for all IPv6 devices on a network.

IPv6 has been part of the RFP process for carriers in Asia for a couple of years, says David Willis, an analyst at Meta Group. While Internet 2 and a number of U.S. carriers are testing IPv6, neither AT&T nor MCI, the two largest service providers domestically, has announced support.

"If the largest U.S. carriers haven't found a need for IPv6 it makes you wonder why Verio needs it," Willis says. While Verio, on its own, might also not need IPv6, it seems that the ISP is bringing its network up to speed with its parent's network.

"NTT is the largest carrier in the world," which might be why it has upgraded many of its Asian networks and also why it is upgrading its ancillary networks, Willis says. "If it streamlines operations and customer support then it's a positive move. But it's not a feature that users in the U.S. are asking for."

"IPv6 is in the early adopter phase," Verio's Barber acknowledges. "There has been higher resistance to IPv6 adoption in the U.S., but it's important to offer users the service to try out."