The Economist : IPv6 Poised For Takeoff

Tuesday, June 10, 2008

NOBODY would expect a city water system designed for 1m residents to be able to handle a 1,000-fold increase in population in just a few years.  Yet that is what the internet’s fundamental addressing scheme has had to accommodate.  When the network was first established there were only a handful of computer centres in America.  Instead of choosing a numbering system that could support a few thousand or million addresses, the internet’s designers foresightedly opted for one that could handle 4 billion.  But now even that is not enough.  The addressing system, called internet protocol version 4 (IPv4), cannot keep up with the flood of computers, mobile phones, hand-held gadgets, games consoles and even cars and refrigerators flooding onto the network.  Nearly 85% of available addresses are already in use; if this trend continues they will run out by 2011, the Organisation for Economic Co-operation and Development, a think-tank for rich countries, warned in May.  The shortage is not the only problem; so too is growing complexity.  IPv4 addresses are allocated in blocks to network operators. The path to reach each network is published on a global list that is constantly updated.  Big computers, called routers, use these entries to guide the flow of traffic across the internet.  But as more devices and networks link to the internet, it becomes necessary to subdivide the address blocks into ever-smaller units.  This risks overtaxing the millions of routers that handle the internet’s traffic, which must be regularly upgraded to keep up.  Were there no alternative to IPv4, parts of the internet would eventually suffer from sporadic outages, warns Paul Vixie, a network engineer who wrote the software the internet uses to translate domain names (such as into their underlying IPv4 addresses.  Fortunately a new system does exist, called internet protocol version 6, or IPv6.  (Version 5 was a short-lived experimental system.)  IPv6 provides 3.4×1038 (4 billion to the fourth power) addresses.  This means IPv6 addresses can be allocated to network operators and companies in much larger quantities.  It also provides a clean slate for establishing new paths over the internet, reducing complexity.  But switching means upgrading millions of devices.  In fact, support for IPv6 is already widely available in software and hardware, but it has not been used much.  Only a few research institutions and the American government took the IPv6 plunge early on.  (In America all federal agencies must be capable of using IPv6 by June 30th 2008, by executive order.)

But in recent months the pace of change has picked up.  In February Mr Vixie and others who operate the “root nameservers”—the central computers that translate domain names into internet addresses—flipped a switch that means domain names can now map onto IPv6 addresses.  This may herald more widespread adoption of the new protocol, since it means that any organisation can use IPv6 addresses with its domain names, and users can access them without special rigging.  Google was one of the first widely used sites to take public advantage of this, setting up, which maps to an IPv6 address for its home page.  Support for IPv6 is already baked into most popular operating-system software.  It is incorporated into Windows XP and Vista, Mac OS X 10.3 “Panther” and later, and many flavours of Unix and Linux.  But operating systems are only the taps of the plumbing system: a house’s other fixtures (like set-top boxes), inside pipes (broadband modems and routers), and feeder pipes (backbone routers) must also be upgraded for the full benefits of IPv6 to become available. In the meantime, IPv4 and IPv6 can co-exist by smuggling data addressed in one form inside packages addressed with the other.  The cost of the upgrade will be distributed across the internet’s many users, from consumers to companies to network operators, and will mostly be a gradual process.  “The internet itself has grown organically—it’s not possible to implement or mandate a change across the network,” says Leslie Daigle, chief internet-technology officer at the Internet Society, a non-profit body that supports the development of internet standards.  But some big network operators may have to upgrade in order to accommodate more devices.  Comcast, an American cable operator, realised in 2005 that it might need 100m IP addresses by 2008, but would be able to get perhaps one-tenth of that number of IPv4 addresses.  It has since converted the core of its network to IPv6.  Pressure to convert entire broadband networks to IPv6, right down to individual PCs, may come from an unexpected source, says Mr Vixie.  “First-person, shoot-’em-up gaming and peer-to-peer file sharing works better if IPv6 is used,” he notes.  And once consumers get a taste of the benefits, he says, the adoption of IPv6 should take off dramatically.

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