"We foresee a gradual, organic growth with IPv6 deployment among our customer base, especially as more and more become aware of the importance to transition," Kim says. "Companies that don't take action toward transitioning from IPv4 to IPv6 risk increased costs and limited functionality online for their users. Ultimately, however, IPv6 will result in faster, more secure, more reliable and cheaper Internet service."
Some experts say that IPv6 is not a sure thing, despite the efforts by the IETF, the Internet Society and other proponents to portray it as such.
Professor Milton Mueller, of the School of Information Studies at Syracuse University and a founder of the Internet Governance Project, points out that network operators can't switch to IPv6 today without cutting themselves off from the IPv4-based Internet. Instead, they have to run both IPv6 and IPv4 side-by-side in a dual-stack configuration or use NAT devices to bridge between the protocols. The awkwardness of this upgrade is why Mueller is not too optimistic about IPv6 deployment.
Five years from now, the Internet could still be "95 percent IPv4," he says. "I think it's possible, and I think it's bad. I can't think of anything better than having abundant address space in economic terms, but the migration strategy of dual-stack is a very strange thing."
Policymakers remain optimistic that IPv6 will eventually catch on because of demographics. The Internet has 2 billion users and is almost out of its IPv4 address supply, while the planet has another 4 billion people who aren't yet connected to the network. Proponents argue that IPv6 is the best path for the Internet to scale to meet the demands of these new users and their devices.
John Curran, president and CEO of ARIN, concedes that there has been little demand for IPv6 during the last decade.
"Nobody needs an oxygen mask on a plane until the plane is going down," Curran says. "The IPv6 need is now upon us, and it will have a significant growth rate over the next five years."
Curran says he's seen "a huge increase" in demand for IPv6 addresses from both ISPs and enterprises. For example, ARIN's IPv6 assignments to ISPs and enterprises rose more than 50 percent in 2010 vs. 2009, and they continued to climb in the first quarter of 2011.
"The number of organizations looking at IPv4 as a dead end is increasing," Curran says. "There's a lot of serious deployment. [Five years from now], IPv6 may still be a smaller amount of Internet traffic than IPv4. But you can't take 4 billion addresses and make them meet a 50 billion type of need."
Geoff Huston, chief scientist at APNIC, the Asia Pacific Network Information Centre, says the purpose of World IPv6 Day isn't so much to drive IPv6 traffic for 24 hours but to address concerns by content providers that IPv6 deployment is expensive and will result in their site being unreachable by a significant number of users.
"The point of the exercise is actually one of myth busting," Huston says. "In and of itself, [World IPv6 Day] won't get the IPv6 ball rolling, but it's an attempt to remove one more element of blockage, namely the fear that the problems caused by going to dual-stack will make the customer experience worse for a significant proportion of the current customer base."
Huston says the greatest risk if IPv6 doesn't get adopted widely is that the Internet will be closed to startups because all of the address space will be held by incumbent network operators.