Yahoo Is Pushing the Industry to Get IPv6-Ready

Yahoo! is proud and excited to participate in World IPv6 Day, scheduled for June 8, 2011.  World IPv6 Day is a global-scale test flight of IPv6 sponsored by the Internet Society (ISOC). Yahoo!, along with other major Web companies such as Google and Facebook, will enable IPv6 on their main websites for a period of 24 hours. The event starts at midnight GMT on June 8, 2011.  (In the United States, that means June 7at 5pm Pacific, 8pm Eastern.)   Everybody participating will enable IPv6 on their sites at the same time.

Yahoo!’s participation in World IPv6 Day will provide real-world data for Internet service providers, hardware makers, operating system vendors, and Web companies.  Key learnings from this event will help the industry work together to ensure a smooth transition to IPv6.

Why Is IPv6 Important for the Internet?
Thirty years ago, the Internet was born.  It was commercialized in 1995, and has been steadily growing since. Though it started out as an experiment, it has grown into a critical part of our everyday lives -- many people now rely more on the Internet than the telephone or the television.

We are now outgrowing the current IPv4 (Internet Protocol version 4) design.  We are running out of distinct numerical IP addresses (similar to telephone numbers) to give users and services.  For the long-term health of the Internet, it is time for it to evolve – to “IPv6”. The primary benefit from this new protocol is a much larger address.  We are moving from 32-bit addresses to 128-bit addresses.  With the telephone analogy, this would be like moving from a 10-digit phone number to a 38 digit phone number.

What Will Happen to IPv4?
The current IPv4 protocol will be with us for years to come.  Many websites and ISP may be slow to upgrade to IPv6.  Some customers may find no value in upgrading their home equipment.

ISPs will be forced to continue delivering IPv4 service despite running out of unique IPv4 addresses.  The realistic solution for ISPs will be to have several houses share a single public address (using NAT, or Network Address Translation).  This will be similar to a telephone party line, where several houses shared a single phone line and phone number.  Basic web browsing and basic mail will still work, but several peer-to-peer applications will break.  Examples of this can include voice and video chat, online video gaming, and file sharing.

The future of IPv4 with address sharing has potential to be more vulnerable for security issues, too.  Today, a common method for websites to deal with hackers and abuse is to block the IP address. What happens if they have to block a shared IP address?  If you have to share an IP address with a thousand neighbors and just one of them has a compromised computer doing Bad Stuff, you might find yourself locked out of your email or banking website.

Wide-scale adoption of IPv6 will bypass these nuisances.  IPv6 will ensure that the Internet experience you have today will be preserved (or improved upon!) in the future.

How Will Yahoo! Participate?
Yahoo!’s goal 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 address space runs out.   Yahoo! is a leader in addressing the scaling challenges facing the Internet and is committed to lead industry players to support the new protocol.

Most of our “front page” websites (such as will be participating in this test.  This includes our international sites.

Only our HTML servers will be dual-stack.  This means that serving our pages will still require IPv4 service for images, scripts, and style sheets.  World IPv6 Day is about enabling IPv6, not about going IPv6-only.   It will be another 2-4 years before one can expect industry-wide support of IPv6-only users.

Destination sites such as,, and others will not be participating in this event; you will still be able to directly visit those sites regardless of what else happens on World IPv6 Day.   API services through the Yahoo! Developer Network will also be unaffected.

How Will This Day Impact You?
Chances are, it won’t.

World IPv6 Day is meant to provide a limited controlled window where any problems can be exposed and corrected.  We expect few problems, since we are at the early stages of IPv6 adoption.  With such a large scale test, however, at least a few problems are expected.

If you are already an IPv6 user, you may see increased latency, due to increased IPv6 traffic.  Circuits and routers may be busier than service providers expected.   You may see connectivity problems not seen previously, due to few web sites today having IPv6 addresses.  In these cases, contact your IPv6 service provider.

One risk category that has been identified involves hosts that have IPv6 enabled, but incorrectly configured.  Industry estimates are that 0.05% of the internet population falls into this category; or 1:2000.

When hosts have IPv6 configured, browsers will prefer IPv6 over IPv4.   This means that when a web site offers both IPv4 and IPv6, the browser will pick IPv6.  When the host is incorrectly configured with a non-functional IPv6 address, this means the browser will spend several seconds (or even minutes) before giving up and trying IPv4.

You can test for this ahead of time by visiting , and trying our online test.

If you do have problems on World IPv6 Day..
First, make sure your internet connection is working.  You can visit to see if you can reach Yahoo! using IPv4.  If that does not work, then ask your ISP for assistance with basic IPv4 internet service.

If fails, but works, you are possibly in the “broken configuration” category.  You can try these steps first; they may fix or at least reduce the slow connection behavior.  Some vendors are working diligently to gracefully handle incorrect IPv6 configurations.

  • Make sure your home router or wifi router is up to date.
  • Make sure your OS is up to date
  • Make sure your browser is up to date
  • Disable “6to4” (automatic tunnels); they allow a transient temporary form of IPv6 .  They usually don’t have a way for you to complain about their service.  You may find this on your host, or on your router.

Disable “Teredo” if you (or software you use) enabled it.  The default Teredo configuration is safe (and only activates under limited conditions).  Some software changes the Teredo settings to encourage always using Teredo for IPv6 addresses.

If these do not help, and you are unable to correct the IPv6 configuration, then you’ll need to disable IPv6.  You will find instructions at .  If you do disable IPv6, you’ll need to re-enable it once your service provider offers IPv6 services.

How do I get IPv6?
Check with your internet service provider.  Many are working behind the scenes to get ready for IPv6.   Some have already started commercial deployments.  We anticipate several IPv6 related services being made available in the next 3-12 months from a broad spectrum of service providers.

If you’re comfortable with the idea of setting up IP tunnels, consider looking for “ipv6 tunnel providers” .  Tunnels are a convenient way to get early access to IPv6, and do early testing of your products.  Keep in mind that tunnels may bypass your firewalls; be sure to do a security review and protect yourself adequately.

Adam Bechtel—Vice President of Infrastructure Engineering