Thirty years ago, when the Internet was just getting started, it seemed a safe bet that 4.3 billion addresses would be more than enough. After all, that was roughly the world's population at the time.
"Who the hell knew how much address space we needed?" said Vint Cerf, Google's chief Internet evangelist, considered the father of the Internet, in an interview last month with Australian journalists. "I thought it was an experiment, and I thought that 4.3 billion (addresses) would be enough to do an experiment."
But now it appears the number was too small.
"It turns out the experiment got out of the lab," said Leo Vegoda, number resources manager at the Internet Corp. for Assigned Names and Numbers (ICANN), in an interview Thursday. "There is a big mismatch between 4 billion and what we need today for a global-spanning telecommunications network that's good for transmitting data packets. We need more addresses."
Every website, computer, smart phone, network printer, cable TV and wireless device out there has a unique numerical IP (Internet protocol) address. As devices and data multiply and the world's population hovers around 7 billion, those IP addresses are now almost exhausted.
On Thursday, the international groups that coordinate Net addresses officially allocated the last blocks of them to five regional registries that in turn distribute to Internet service providers, websites and so forth. Those final allocations could be used up within months.
That means the Internet must now switch to a new address protocol. It's a bit like an overpopulated area code that's out of phone numbers - but instead of just creating a new area code, the behind-the-scenes IP addresses will become a lot more complex.
Seamless - for now
For most users, the transition should be seamless - until a few years from now, when people with older modems may need to upgrade them to recognize the new addresses.
The current system, IPv4 (version 4) uses "dotted quads" - four numbers separated by periods. For instance, the IP address for www.sfgate.com is 22.214.171.124. (Domain names, such as sfgate, essentially act as an address book, providing an easy way to look up IP addresses.)
The new system, IPv6, uses 128-bit addresses. A typical IPv6 address might look like this: 2001:0db8:0234:AB00:0123:8a2e:0370:7334.
It can handle a huge number of addresses, 340 undecillion, to be precise. That number can be expressed as writing 3.4 followed by 38 zeroes, said David Ulevitch, founder and CEO of OpenDNS, a San Francisco company that translates domain names into numbers.
"The (IPv4) trough is now empty," Ulevitch said. "The Internet continues to grow, and the only way to grow is to use IPv6."
The new protocol
In fact, enterprises have been experimenting with the new protocol for over a decade, but the imminent exhaustion of IP addresses provides motivation to step up those efforts, he said.
June 8 has been designated as the ultra-nerdy "Test Flight Day" when Google, Facebook, Yahoo and other major companies will offer their content over IPv6 to motivate ISPs, hardwaremakers, operating system vendors and others to handle the new addresses.
"It's drawing a line in the sand as to when everyone supports this important technology," said Greg Smith, senior director of technical marketing for Citrix Systems, which sells products to translate the older version of IP addresses to the new ones. "There's a chicken-and-egg dynamic: it requires some investment on the part of websites and companies and they don't want to make it until they see demand."
"This is not sneaking up on anybody," said Bill Woodcock, research director at San Francisco's Packet Clearing House, a nonprofit that researches Internet traffic and global network development. "IPv4 addresses will continue working exactly as they always have."
Some people with older modems may be affected eventually once the new protocol becomes the default.
"A lot of DSL modems and cable modems out there right now don't support v6 because they are the cheapest and most commodity pieces of gear and vendors didn't require their hardware providers to do that engineering until recently," Woodcock said. "At some point those may need to be swapped out."