Similarly, Facebook served content to more than 1 million IPv6 users on World IPv6 Day. But this represented only a small fraction -- 0.2% -- of Facebook users that are IPv6 capable. Of those Facebook users, 0.16% had native IPv6 access and the other 0.04% used 6to4 tunneling.
"There are some people who are very, very passionate about IPv6 ... but it's difficult for most people to understand," said Donn Lee, a member of Facebook's network engineering team. "It's very much a concept of, 'I have restored my Internet connection.' That's what the user cares about. The user doesn't care about if it's IPv6 or IPv4."
The IETF created IPv6 a decade ago 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 (ARIN), 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 (NAT) devices.
One major stumbling block for IPv6 deployment is that it's not backward compatible with IPv4. That means website operators have to upgrade their network equipment and software to support IPv6 traffic.
DETAILS: Getting at the real truth about IPv6
IETF participants agree that World IPv6 Day was a success in terms of setting a deadline for content providers to support IPv6 and encouraging collaboration across the Internet industry.
World IPv6 Day "certainly spurred a number of organizations to roll out IPv6 even on a test-flight basis," said Leslie Daigle, chief Internet technology officer for the Internet Society. "We saw no large-scale breakage ... and the DDoS fears did not pan out. Overall, it was a success. We moved the needle on IPv6 deployment.''