There are no more IPv4 addresses to allocate. Finito.
At the end of January, the Internet Assigned Numbers Authority (IANA) allocated two blocks of IPv4 address space to APNIC, the regional internet registry for the Asia Pacific, which triggered a global policy to allocate the remaining IANA pool equally between the five regional registries. As of 3 February, every last IPv4 address was allocated.
Whatever the registries have left to distribute is all that is left of IPv4. APNIC , for instance, handed out 24 million addresses in January and is believed to have 100 million left so will run out in the coming months. ARIN, the North American registry, has about 140 milllion left to distribute.
How is it that something we all knew was coming still seems to take many of us by surprise?
Version 4 of the Internet Protocol (IPv4) used an address format consisting of four sets of numbers. The combination of these numbers created an address space of around four billion, which IPv4’s creators thought would be enough in 1980, when the PC was just being launched and when telex machines were still de rigeur.
So what happens when we really can't squeeze another address out of IPv4?
The Internet will not suddenly implode. For one thing, many IPv4 addresses are reusable. For another, carriers and ISPs are likely to start using large network address translation systems to represent multiple individual addresses with a single IPv4 address.
But in the longer run, the switch to IPv6 is inevitable.
IPv6 uses a much larger address space than IPv4 - enough for far more than every grain of sand and blade of grass on the planet. But moving to IPv6 can be is a complex technical task, especially as it will need to map to IPv4 systems for many years to come.
Nevertheless, Cisco, Juniper, Yahoo, Google, Akamai, Facebook and a host of others have already committed to make switch their web sites over to IPv6. They will participate in the Internet Society's World IPv6 day - a 24-hour test run of IPv6-based network services which is scheduled for 8 June 2011.
The companies expect connectivity problems for some users, largely based on incorrect home network configuration, which is one reason why it is important to ease the new protocol in gradually. But other organizations, such as the US military, are heavily promoting IPv6 use.
Over the next couple of years, expect an exponential growth in IPv6 as organizations rush to future-proof their networks.
I've been writing about technology for nearly 20 years, including editing industry magazines Connect and Communications International. In 2002 I co-founded Futurity Media with Anthony Plewes. My focus in Futurity Media is in emerging technologies, social media and future gazing. As a graduate of philosophy & science, I have studied futurology & foresight to the post-grad level.