On January 31, 2011, the last of the 4.1 billion available IP addresses was allocated. Those IP addresses are called “Internet Protocol Version 4” (IPv4 for short) and look something like this: was created by Vinton Cerf eight years before the World Wide Web made its debut and is the most widely deployed Internet layer protocol today. He was recently asked about IPv4 running out of IP space and responded that he never expected IPv4 to take off, adding, “Who … knew how much address space we needed? It was 30 years ago!”

So why are we not hearing about the end of the Internet? Well the reason has two parts:

Reason Part One: “Allocated” IPs do not equal “used” IPs. Allocated simply means that the IP address has been designated to a person or entity. A large company, for instance, might have many IP addresses in use and many others that are already allocated to them but not being used. At this time, it is estimated that 14% of IPv4 addresses are in use.

Reason Part Two: There is a new version of IP called IPv6. Instead of 4.1 billion IP’s (like IPv4), IPv6 has three hundred and forty undecillion, two hundred and eighty-two decillion, three hundred and sixty-six nonillion, nine hundred and twenty octillion, nine hundred and thirty-eight septillion, four hundred and sixty-three sextillion, four hundred and sixty-three quintillion, three hundred and seventy-four quadrillion, six hundred and seven trillion, four hundred and thirty-one billion, seven hundred and sixty-eight million, two hundred and eleven thousand, four hundred and fifty-six IP addresses.

Because we are running out of IPv4 addresses, we will need to migrate over to the new IPv6 addresses eventually. This is not as simple as taking the old address (to continue our earlier example) and adding on more, to get an address such as IPv6 addresses use both letters and numbers, resulting in addresses that look like this — 3ffe:1900:4545:3:200:f8ff:fe21:67cf.

All the equipment from your cable modem, router and computer must support IPv6. If your cable modem and router are less then 2 years old, you should be fine. And any computer from Windows XP on is also ready for IPv6. If you’re interested in checking your IPv6 readiness, use this site: http://test-ipv6.com.