It is World IPv6 Launch Day. In one way, IPv6 is old news in that many communications companies are already supporting IPv6 in at least parts of their networks; for example, Comcast yesterday said it supports it across about one-third of its footprint.

But that was a necessary prerequisite for content sources to begin supporting IPv6. The event today focuses on websites; participants include the four most visited websites in the world – Google, Facebook, YouTube and Yahoo – as well as home router manufacturers and Internet service providers (ISPs) in more than 100 countries, according to the Internet Society, which organized World IPv6 Launch Day.

That merely underscores that World IPv6 Launch Day is neither a start nor an end to the rolling out of support for IPv6, but is one of the earlier midpoints in a long and gradual process that will include dual support for both IPv4 and IPv6 for many years to come.

According to a survey of IT professionals around the world conducted by BT, only about 13 percent of organizations have already rolled out IPv6 across part or all of their networks. A further 44 percent of respondents plan to roll out IPv6 within two years, given the twin developments of an ever-expanding Internet and a rapid depletion in IPv4 addresses, BT said.

Despite the explosive growth in the number of devices connected to the Internet and the imminent depletion of IPv4 addresses, the BT survey found that some IT professionals remain unconvinced the transition to IPv6 requires their support or participation. BT’s survey found 22 percent of respondents still believe that a stronger business case needs to be created to demonstrate sufficient return on investment.

Another barrier is the perception of complexity in terms of the infrastructure needed, BT said, although nearly 60 percent of respondents agreed that IPv6 technology is now sufficiently mature to move ahead.

Of course, there remain details to be sorted out. Xerocole CTO Rob Fleischman has posted a video in which he discusses some of the potential DNS pitfalls associated with IPv6 deployment.

"Most of the equipment and software used by Internet service providers has been IPv6-compliant for a while," Fleischman said. However, "as it turns out, there are a few issues that could cause broadband Internet providers some problems, which are worth sharing."

Under some circumstances, record queries could cause PCs to time out, Fleischman said. The use of anti-spam black lists could be problematic under some circumstances. DNS inquiries might double; any ISP not prepared to handle the increase might choke on the traffic. Another example is that handling reverse DNS could become a significantly more difficult task.

"IPv6 is critical to the future of the Internet's underlying architecture and to supporting the billions of devices that will connect to the Internet over the coming years," said Tom Leighton, chief scientist and co-founder of Akamai.

John Schanz, Comcast’s chief network officer, said, "I am happy to report that by today, we have exceeded our goal of 1 percent of our customer base being enabled with IPv6 for World IPv6 Launch!"

David Krozier, network infrastructure analyst at Ovum, believes the launch will mark the culmination of ISPs' efforts to turn up commercial IPv6 services. He said: "Verizon currently supports enterprise and government customers with native and tunneled IPv6 services. The Verizon LTE network is enabled for IPv6, and the company is testing IPv6 on its FiOS network.

“AT&T set a 2020 date for full IPv6 deployment and offers IPv6 commercial services on its U-verse network. … Comcast has turned up IPv6 services to more than 1 percent of its residential wireline subscribers, and Time Warner also offers IPv6 to residential subscribers. Around the globe, Internode (Australia) supports IPv6 services with a dual-stack network, and ISPs in Hong Kong, as well as KDDI, XS4ALL and Free Telecom, are all offering IPv6 connectivity."