The World IPv6 Day, initiated by the Internet Society (ISOC), is a 24 hour trial period or 'Test Flight,' where a number of major web sites will provide their content on both IPv4 and IPv6. The goal of the Test Flight Day is to motivate organizations across the industry – Internet service providers, hardware makers, operating system vendors and web companies – to prepare their services for IPv6 to ensure a successful transition as IPv4 addresses run out.
The address space used by the current version of the Internet protocol, IPv4, is expected to run out in 2011. As a measure to meet this crisis, Internet Society introduced cross-over to IPv6, which provides over 4 billion times more space.
IPv6 is used extensively in many large networks, but it has never been enabled at a global scale. World IPv6 Day will help industry players work together to support the new protocol on an accelerated timeline. Internet giants like Google, Yahoo, Akamai and Limelight Networks have agreed to offer their content on IPv6 on Test Flight day.
"The vast majority (99.95%) of people will be able to access services without interruption: either they"ll connect over IPv6, or their systems will successfully fall back to IPv4. However, as with any next-generation technology, there may be teething pains," Google said in its blog.
"We estimate that .05% of systems may fail to fall back to IPv4, so some people may find Google, Facebook, Yahoo, Bing and other participating websites slow or unresponsive on World IPv6 Day. This is often due to misconfigured or misbehaving home networking equipment, such as home routers, that can make a computer think it has IPv6 connectivity when in fact it"s not working."
Users can visit an IPv6 test site to check if their connectivity will be impacted. If the test indicates a problem, they can disable IPv6 or ask their ISPs to help fix the problem.