"It was perceived to be quite a successful day," Daigle said. "It was an amazing display of cross-industry participation.... It's an important step in the Internet's progress. We are running out of IPv4 addresses, and IPv6 is definitely the way to move forward to make sure the Internet is a platform for innovation."
Yahoo said it only had to make one minor adjustment to its website for traffic optimization as a result of World IPv6 Day.
"Yahoo is very excited about how smoothly World IPv6 Day went for everybody. It's a great testament to the preparation that went into this event," said Jason Fesler, an IPv6 architect at Yahoo. "The early data says there is minimal risk to pushing forward."
Akamai and Limelight also said they were stepping up their efforts toward full, commercial-grade support of IPv6 due to the success of World IPv6 Day.
"We're going to look at the data for IPv6 usage and use that to improve our services," said Andy Champagne, director of engineering at Akamai, which had 30 customers participate in World IPv6 Day using its beta IPv6 service. "Then we are going to work with our customers to roll out IPv6."
Tom Coffeen, director of global network architecture for Limelight, said it had IPv6-enabled every server on its network for World IPv6 Day and that it had encountered only minor issues that involved some routing policy changes.
"We were surprised and pleased to see no bugs. The few issues we did encounter were quickly resolved," Coffeen said. "We had many customers choosing to stay IPv6-enabled going forward. We're ready to move to an opt-out model for our customers, where they have to request no IPv6 availability."
Despite these successes, World IPv6 Day participants conceded that IPv6 still has a long way to go before it approaches the ubiquity of IPv4.
Colitti said Google estimates that only 0.3 percent of its users have adopted IPv6. He said it was too early to determine how many of its users suffered from broken IPv6 connections; estimates prior to World IPv6 Day put IPv6 brokenness at 0.03 percent to 0.05 percent of Internet users.
Similarly, Lee said that Facebook estimates that about 0.2 percent of its users were able to reach the website via IPv6.
"Once the world gets to about 1 percent adoption [of IPv6], then this will be for real," Lee said. "That's the initial mass that you need to have for global adoption."
Content providers are migrating to IPv6 because the Internet is running out of addresses using IPv4. The free pool of unassigned IPv4 addresses expired in February, and in April the Asia Pacific region ran out of all but a few IPv4 addresses being held in reserve for startups. The American Registry for Internet Numbers, which doles out IP addresses to network operators in North America, says it will deplete its supply of IPv4 addresses this fall.
IPv4 uses 32-bit addresses and can support 4.3 billion devices connected directly to the Internet, but IPv6 uses 128-bit addresses and can connect up a virtually unlimited number of devices: 2 to the 128th power. IPv6 offers the promise of faster, less-costly Internet services than the alternative, which is to extend the life of IPv4 using network address translation devices.
Read more about lan and wan in Network World's LAN & WAN section