Are your networks ready for the cutover to IPv6?

June 8 is World IPv6 Day, when Google, Akamai, Facebook, and Limelight test their IPv6 stacks. Find out now if your home and corporate networks are ready

The Internet is running out of the equivalent of phone numbers -- familiar problem, nontrivial solution.

You probably already knew that the Internet is running out of 32-bit IP addresses. You may not have known that 98 percent of the available 4,294,967,296 addresses are already allocated. According to the automatically generated Potaroo IPv4 Address Report -- you can even download a Windows gadget to perform the countdown in real time -- we'll run out of unallocated address pools on Feb. 19, 2011, or about five weeks from now. That doesn't mean the Internet will come crashing down, but it does make life much harder for those who have to assign IP addresses.

[ InfoWorld's Mel Beckman warns of a black market for IP addresses due to the looming IPv4 shortage. ]

The world has to move to IPv6, with its 128-bit addresses. But that's easier said than done.

Generally, it isn't a question of getting clients to run IPv6. The various Windows, Mac OS, and Linux OSes all have IPv6 support. Windows 7's Homegroup feature runs over IPv6. The problem lies in getting the world to speak IPv6. Equipment that needs to look at IP addresses -- routers, for example -- must be IPv6-savvy. Chances are good your company's equipment speaks IPv6, but your home router may need a firmware upgrade. There are many other potential choke points.

While the world makes the transition from IPv4 to IPv6 -- a process that will take many years -- websites will need to run "dual stacks" to allow access via either the IPv4 or IPv6 protocols. That's the source of most of the problems: If your network supports both IPv4 and IPv6, but the IPv6 access isn't working right, and you go to a site with dual stacks, your system may hang for more than a minute trying to get into the IPv6 part of the site.

ISOC, the international Internet society, just announced World IPv6 Day -- the largest IPv6 testing experiment to date -- which will run for 24 hours on June 8. On that date Google (and YouTube), Facebook, and Yahoo will all turn on their IPv6 stacks, as will the major behind-the-scenes delivery networks Akamai and Limelight Networks.

As Lorenzo Colitti puts it on the Google blog, "Our current measurements suggest that the vast majority (99.95 percent) of users will be unaffected. However, in rare cases, users may experience connectivity problems, often due to misconfigured or misbehaving home network devices." Donn Lee on the Facebook blog says, "about 0.05 percent of Internet users (1 in 2,000) can't reliably connect to websites that enable both IPv4 and IPv6 addresses ... websites don't want to enable IPv6 because a small number of their users may have trouble connecting. At the same time, doing nothing means that ever more users will have trouble connecting to these dual-stacked websites."

Some networks -- even some fancy, well-honed corporate networks -- are going to fall over on June 8. Bet on it. If you have trouble connecting to Google on June 8, cut your network folks some slack. They may be fighting fires all day.

If you want to test your connection right now, hop over to the Test-IPv6 site and see if you have IPv4 and IPv6 running properly. If your corporate network isn't set up to browse IPv6 sites just yet, not to worry. That will come with time. The forced cutover to IPv6 is many, many years away. For now, you primarily want to know if your connection will fall over with a site that has both IPv4 and IPv6 stacks running. Test-ipv6 will tell you.

If you fail the Test-IPv6 run, let your network admin know. There's a series of steps they can follow to run down the problem, posted on the Test-IPv6 site.

This article, "Are your networks ready for the cutover to IPv6?" was originally published at Get the first word on what the important tech news really means with the InfoWorld Tech Watch blog, and for the latest in business technology news, follow on Twitter.

Copyright © 2011 IDG Communications, Inc.

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