Thursday, March 17, 2011

Bumps in the road to IPv6

By Woody Leonhard

Although the consequences aren't as dire as it sounds, the Internet ran out of IP addresses (roughly analogous to telephone numbers) last month.

While the Web won't come crashing down anytime soon, you're going to be affected by the new numbering scheme — and some details may catch you unawares.

Last October, Fred Langa talked in his LangaList Plus column about the changes under way. Simply put, the Internet has run out of IP addresses under the old IPv4 scheme.

This is no namby-pamby upgrade. The current 32-bit IPv4 scheme can handle just under 4.3 billion different Internet addresses. And we've used them up. (That represents an astounding number of networked devices potentially in use.) The new, 128-bit, IPv6 numbering method can accommodate 340 trillion trillion trillion addresses. It's, ahem, unlikely that we'll need that many addresses anytime soon.

But IPv6 incorporates much more than added addresses. There's a complex scheme of layering, protocols, security, and communication enhancements buried in the standard. For the most part, you won't have to worry about the details. But there are a few areas where you can help — and where you can be taken in. Caveat surfor! (Web-surfer, beware!)

Moving to a new format for IP addresses

An IP address identifies a specific piece of hardware on a network — one device, one unique IP address. And the Internet has grown into a mighty big network — with far more devices attached to it than anyone could have imagined back in 1977, when IPv4 was invented.

IPv4 addresses are expressed in four groups of numbers between 0 and 255. For example, or No doubt you've struggled with them at some point.

The Internet Assigned Numbers Authority (IANA) assigns IPv4 addresses in blocks of 16 million addresses to each of five Regional Internet Registries. There are RIRs for Africa, the U.S. and Canada, Australasia, Latin America, and Europe/Middle East/Central Asia. Each RIR in turn assigns blocks of addresses to Internet Service Providers and other organizations. On Feb. 1, IANA gave out the last blocks of IPv4 addresses to its five RIRs.

That does not mean we're facing an imminent crisis. It'll take years for all RIRs to allocate all numbers, and there are tricks that can shuffle numbers around (prompting worries of a possible black market in IP addresses). But the writing's clearly on the wall — we're running out of the Internet's phone numbers.

(IP addresses should not be confused with MAC addresses. IPs are issued to networked devices by the Internet service provider. In most home networks, the IP address is dynamic — it can change when you connect to an ISP. Mac addresses are assigned by the device manufacturer and are essentially a unique, fixed identifier for the device's network interface — and thus for the device.)

To handle the vast number of computers and other devices now connecting to the Internet, the IANA and ISPs are in the process of rolling out IPv6. The new IPv6 addresses appear as a group of eight numbers, each with four hexadecimal digits, such as:


Clearly, we aren't going to wake up one morning to find the Internet working with IPv6. Instead, there will be a period of years — probably many years — where IPv4 and IPv6 need to peacefully coexist.

And that's where the so-called dual stack comes into play.

Testing for dual-stack compatibility

Running IPv6 on Windows is a piece of cake: IPv6 has been built into Windows since XP Service Pack 2. If you are using HomeGroup on Windows 7, you already have IPv6 up and working between your homegrouped PCs. Similarly, all modern versions of Linux and Mac OS speak IPv6, as do most smartphone operating systems.

The problem isn't on your desktop, laptop, or phone. The problem lies in all of the gear between you and your destination. You may or may not be able to get through on an IPv6 connection because your router or your ISP's equipment can't handle it. That's why, for the foreseeable future, most major websites will be running dual stacks, which allow you to get into the site on either an IPv4 or IPv6 connection.

If you're running only IPv4, you'll be just fine for the foreseeable future; your equipment speaks IPv4, and the Internet location you're connected to still speaks IPv4 (and IPv6 with a dual stack).

A problem arises, though, if your router or your ISP's equipment thinks it can handle IPv6 and really can't. Your PC tries to connect via IPv6 but something gets lost in the communication. You might experience delays of a minute or more while your PC battles with the site's IPv6 stack, can't get through because of intermediary problems, gives up after a while, and finally falls back to IPv4.

For that reason, the international Internet Society (ISOC) is throwing a World IPv6 Day on June 8 — 24 hours for website owners, ISPs, and network users (that's us) to take an IPv6 test flight. ISOC has arranged for Google, YouTube, Facebook, Yahoo, and a hundred other sites to turn on their IPv6 stacks. Two of the biggest Internet plumbing organizations, Akamai and Limelight Networks, will also enable IPv6 on that day. The idea is to test all the intermediaries — ISPs and other network operators, plus router hardware manufacturers — to see which of them will fall over when dual stacks become commonplace.

On a Facebook blog, Donn Lee put it this way:
"Testing IPv6 is important because recent studies indicate about 0.05% of Internet users (1 in 2,000) can't reliably connect to websites that enable both IPv4 and IPv6 addresses (known as "dual-stacked" websites). This has resulted in a classic chicken-and-egg puzzle right now: websites don't want to enable IPv6 because a small number of their users may have trouble connecting."
As June 8 rolls around, you might want to let your friends and colleagues know that they're going to be part of a huge test. Have them go to one of the test sites and see whether the connection goes through. If it fails, have them complain — loudly — to their Internet Service Provider.

You don't have to wait for June 8, though. ISOC has a website set up to perform a one-off test of your current configuration. Go there now, and you'll receive a report like the one in Figure 1.

IPv6 Test Resulrts
Figure 1. ISOC's test page tells you in advance whether you're going to have trouble on June 8.

Make sure you buy IPv6-capable routers

Incredibly, some router manufacturers are peddling goods that aren't yet IPv6-compatible. If your ISP provided the router you're using now, you don't need to worry about it — sooner or later, they'll have to ensure it runs IPv6 and the swap-out shouldn't cost you anything. (Not directly, anyway.)

But if you're buying your own router, be very aware of the fact that most consumer routers don't run IPv6. Julie Bort at InfoWorld reported that, as of a month ago, none of Cisco's consumer Linksys routers runs IPv6. For a follow-up story, Cisco stated that "Linksys routers being launched this spring will have IPv6 support" and that the "Linksys E4200 router we launched in January will have an [IPv6] firmware upgrade planned for April." But there's still no word about which, if any, of the zillions of legacy Linksys routers will run IPv6.

If you're thinking about buying a router and want to make sure it'll run IPv6, you can look on the box to see whether it's certified by the IPv6 Forum. If you want the full details, though, check whether the router is listed on the American Registry for Internet Numbers (ARIN) Broadband CPE analysis site. Bet you'll be a little bit surprised — and not pleasantly.

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