As I write this in late October 2010, the Internet is officially down to less than 5% of the possible IPv4 addresses. The bad news? It's actually worse than that, according to the real-time IPv4 Address Report, we're down to 4%. At this rate, local ISPs and businesses won't be able to get new IP addresses after January 2012.
That doesn't mean that Internet addresses won't be available. They will be. But, as with good domain names, you can expect to start paying a pretty penny for your IP (Internet Protocol) addresses. This won't matter so long as you or your business doesn't expand or move, but when you do, as time goes on you can expect to pay progressively more for your new addresses.
"Imagine the IPv4 address space is [a] 1.6-inch square. In that case, the IPv6 address space would be represented by a square the size of the solar system."
When the Internet began, IPv4's possible 32-bit 4.3 billion addresses looked like more than enough. We didn't see mobile devices coming or predict that people would start carrying two or three IP devices -- smartphone, laptop, tablet, MP3 player, etc. -- at once. We could blame Vint Cerf for this vision failure, but it's too late to play the blame game. It's time to start working on the problem.
Let me point out that although that the IPv4 shortage isn't an emergency, it's still an issue that businesses need to start addressing now. Tried and true technologies like Network Address Translation (NAT) will not be able to save us from the growing Internet address shortage. Eventually you will need to be running IPv6.
IPv6 addresses explained
So what does IPv6 bring to the table? Well, for one thing, instead of a mere 4.3 billion possible addresses, IPv6, with its 128-bit address space can have, deep breath, "340,282,366,920,938,463,463,374,607,431,768,211,456." Or, as one person put it: "imagine the IPv4 address space is [a] 1.6-inch square. In that case, the IPv6 address space would be represented by a square the size of the solar system." In short, we're not going to run out of IPv6 addresses any time soon.
With IPv6, every device, and I mean every last one, can have its own unique IPV6 address.