Toward the end of the last century, the biggest threat to IT — and the organizations it supported — was the so-called millennium bug. In the event, planning, investment and hard work helped IT systems to remain stable throughout the switch from 1999 to 2000.

Today’s CIOs and Internet service providers (ISPs) face a replay of that challenge: the migration from IPv4 to IPv6. The last of the 4,294,967,296 unique Internet addresses available under the 32-bit protocol IPv4 (in place since the 1980s) was allocated in February of this year. Its successor, the 128-bit IPv6, supports 340 trillion trillion trillion addresses. But there are significant compatibility issues which could result in organizations being cut off from part of the Internet, unable to reach, or be reached by, partners and customers.

Some of the back-end work needed to address the problem has already been completed. Windows 7, Mac OS X and Linux all support IPv6, as do Android and Apple’s iOS. Meanwhile vendors and ISPs are working to ensure their products and services can handle the new protocol. And on June 8 major players such as Google, Facebook and Yahoo will participate in “World IPv6 Day” to thoroughly test their own, and other organizations’, migration strategies.

During what is likely to be a lengthy transition period, IPv4 and IPv6 will, by necessity, co-exist. Most current Internet content will be on IPv4, but organizations coming online from now on will be on IPv6. To ensure these new customers can reach IPv4 content, broadband providers are commonly deploying centralized network address translators (NATs) or using a protocol translator that allows IPv6 devices to talk to IPv4 devices.

Neither of these solutions is perfect, however. Both are stop-gaps that prevent some applications — such as VoIP and Universal Plug-and-Play — from working. They degrade performance and increase the likelihood of system failures. And applications that identify users by IP address will stop working if the user is behind a centralized NAT.

Organizations are having to address these problems, upgrade technology and look at security (still immature on IPv6), staff training, online strategy and budgetary implications. In terms of effort and investment, it’s a challenge that bears more than a slight resemblance to the Y2K scenario — but it remains to be seen if a similar outcome will be achieved.