"Some providers are migrating their real infrastructure -- including email -- to IPv6, and that's a good sign," Iekel-Johnson said. "But until regular people are using IPv6, we can't claim success. Clearly we still have a way to go, but we are moving in a successful direction."
Michael Bailey, assistant research scientist at the University of Michigan, said his National Science Foundation-funded research also shows a positive long-term adoption trend for IPv6.
"The long-term trend has been a slow-and-steady increase in the amount of IPv6 traffic, the amount of name servers that are addressable via IPv6 and the amount of DNS resolvers that are querying IPv6," Bailey said. "We see similar patterns with IPv6 allocations from the regional registrars and the routing data and naming data."
Bailey called World IPv6 Launch Day a success in terms of proving that IPv6 is ready for deployment, but he warned that "there is a long road before IPv6 is in parity with IPv4."
Nonetheless, ISPs are optimistic that IPv6 traffic will continue to rise during the rest of 2012.
Hurricane Electric, a Fremont, Calif., ISP that claims the world's most interconnected IPv6 backbone, said its IPv6 traffic volumes rose more than fivefold in the week leading up to World IPv6 Launch Day.
"I think we've begun to see the knee in the curve of IPv6 adoption," said Owen DeLong, IPv6 evangelist and director of professional services at Hurricane Electric. "I think we are going to normalize, where we are going to see 1% to 2% growth per day from now on."
DeLong pointed out several statistics that he believes will drive IPv6 traffic growth through the end of the year and beyond:
-- 85% of the Internet's top-level domains such as .com, .net and .org support IPv6.
-- 3.6 million registered domains have the AAAA records needed for IPv6 connectivity.
-- 13% of networks are running IPv6 (as measured by the Autonomous System Numbers in the global routing table).
He also said that the depletion of unassigned IPv4 addresses in Europe, which is expected this summer, could create a spike in IPv6 activity, as might the U.S. federal government's mandate for agencies to support IPv6 on their websites by Sept. 30, 2012.
"I think we'll have a few big publicity events going forward that will drive a few amps of IPv6 traffic, but overall I think we're going to see continued, steady growth," DeLong added.
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