World IPv6 Day begins 24 hours from now. Websites, start your engines.

Back in January, we joined the Internet Society and a handful of leading Internet companies to announce World IPv6 Day. The announcement was a rallying call for adoption of the new Internet Protocol; now, less than six months later, participation has grown to more than 400 organizations. We believe this is an important milestone, as IPv6 is the only long-term solution to IPv4 address exhaustion, and its deployment is crucial to the continued growth of the open Internet.

About 24 hours from now, at midnight UTC on June 8 (Tuesday afternoon in the U.S., Wednesday morning in Asia), all the participants will enable IPv6 on their main websites for 24 hours. For Google, this will mean virtually all our services, including Search, Gmail, YouTube and many more, will be available over IPv6.

In all likelihood, you won’t even notice the test. 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. 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.

Over the past few months, we’ve been working hard with other industry players to prepare. Operating system vendors and browser manufacturers have been releasing updates to resolve IPv6 connectivity issues—for example, Google Chrome now incorporates workarounds for malfunctioning IPv6 networks—and we’ve seen router manufacturers test their devices for robust IPv6 support as well. For our part, we’ve been busy adding IPv6 support to services that didn’t yet have it, and fixing minor issues with those that did. And since the best way to find bugs in your services is to hammer on them yourself, Google employees have been operating in “World IPv6 Day mode” for several months now.

We’ve also been thinking about how best to notify people who may have connectivity issues. To that end, we’ve run a prominent notice in Google Search for people who may not be able to connect, directing them to a new test page and help article. If you’re curious, you can test your connection now at ipv6test.google.com.

Update 5:37 PM: The test flight was a success. World IPv6 Day is over, and IPv6 access to Google services remains enabled only for users in the Google over IPv6 program. We carried about 65% more IPv6 traffic than usual, saw no significant issues and did not have to disable IPv6 access for any networks or services. Over the next few weeks, we’ll be working together with the other participants to analyze the data we’ve collected, but, at least on the surface, the first global test of IPv6 passed without incident.

Posted by Lorenzo Colitti, Network Engineer and IPv6 Samurai