Thursday, May 08, 2008

Where Have All The IPs Gone?

"Where have all the IPs gone? Gone to users every one."
- apologies to Pete Seeger

Have you heard? The Internet is full. In just a couple of years it will have completely maxed out. That means no more users, no more Web sites, no more anything. They'll have to put a bouncer at the door. Nobody else gets in until somebody leaves. "Here, take a pager and we'll call you when it's your turn." Is this anyway to run an Internet?

Wait just a second. Don't they call it the World Wide Web? How come this grand global resource is already at capacity? It's not bandwidth or availability of connections or the price of computers that's the issue. It's addresses. Just like airline seats, there's an available number of places to squat on the Internet. When they've all been handed out, that's it. They're all gone and there aren't any more.

This limitation lies in the design of the Internet Protocol itself. We're currently using Internet Protocol version 4 or IPV4. Back in the dawn of the Internet, when it was the outgrowth of a government research program and used primarily by universities, a 32 bit address field looked like more than enough to accommodate the foreseeable number of users. The 4 bytes of addressing creates a little over 4 billion addresses. It's 4,294,96,296 different numbers to be precise. You'll recognize them in the familiar dot notation used for IP addresses, such as That one is especially familiar because it is reserved as the local host address for the computer you happen to be using. Reserved addressed are one of the reasons there is a shortage, but not the big one.

The problem is that the Internet took off way beyond the designer's imaginations. Everybody is on the Internet or will be just as soon as they can afford a computer or time at an Internet cafe. How many of us? According to the World Internet Usage Statistics, it's now 20% of the world's six billion plus population or 1.36 billion users and growing like mad. North America has a 72% usage rate. It's just under 14% in Asia, and they have the bulk of the population. So there's 1.36 billion users right now and room for 4 billion. Where's the problem?

To find the bottleneck, let's see where all those addresses are assigned. IP addresses are assigned by the Internet Assigned Numbers Authority (IANA) and operated by Internet Corporation for Assigned Names and Numbers (ICANN). They have the addresses arranged into blocks identified by the first set of numbers or octet. In the localhost example, 127 is a first octet number. Class A networks have first octet numbers from 1 to 127. These are for the largest networks, such as those operated by a large organizations or governments. Class B networks have the range between 128 and 191. Class C networks, the smallest, have the range from 192 and 223. Class A networks are rare because there can only be 126 of them, less the reserved numbers. Each class A network can accommodate over 16 million hosts. Each class C network can have 254 hosts. A corporation may have one or more blocks of class C addresses assigned to it.

This assignment into blocks ranging from 254 to over 16 million at a crack has been part of the problem. Some organizations were assigned many more addresses than they are actually using. That wasn't much of an issue until the growth of the Internet began to make large unassigned address blocks in short supply. At that point the strict class system was abandoned in favor of giving organizations what they need but not letting them sit on thousands or millions of unused addresses. Even that wasn't enough to free up sufficient address space forever. In fact, we probably would have run out by now if it wasn't for NAT or Network Address Translation.

NAT is what is built into your router. You may get one static or dynamic IP address from your ISP, but your network could have a dozen or a hundred devices attached. The router keeps track of who is asking for what on the Internet and multiplexes, or shares, that single IP address among all the users on the network.

Even with NAT, it is estimated that we could still run out of IP addresses by 2010 or perhaps push that out another 5 to 7 years by making organizations give back any unused address space they've been assigned. That kind of scrounging might help temporarily, but it will never solve the problem. It's not just users logging into ISPs that grab all the addresses. Many IP addresses are used by Websites and email servers. Newer devices such as IP security cameras may have their own IP addresses so you can call them up remotely. Wireless access points and anything else that connects to the Internet wants its own IP address, either globally or locally assigned.

What we really need to solve the problem is more addresses and the way to do that is to expand the address space with a new version of the Internet Protocol. IPV6 does just that. Internet Protocol version 6 is the designated replacement for IPV4 and it is in the process of deployment. The U.S. Government hopes to be completely on IPV6 by the middle of this year. China is going the same way for its Next Generation Internet. How much extra will become available by using IPV6? It's not double or even ten or a hundred times, like you might expect. No, the designers of IPV6 weren't going to get caught short this time around. The IPV6 address space is 128 bits wide. That's not just 4 times the size of the 32 bit IPV4. The way it multiplies as you add bits makes IPV6 capable of trillion, trillion, trillions of individual addresses. Take all you want, there's plenty to go around.

IPV6 is just what's needed to enable the everything-Internet society. Your computer, cell phone, television, refrigerator, and nanny camera can all have their own addresses. Hey, chip your dog and make him Internet enabled. Or chip yourself. Oh, that's going to be an issue. NAT provides a convenient way to keep hackers and other outsiders from knowing what's on your network and how to get to it. One of the challenges of moving to IPV6 is going to be maintaining privacy in a world where everything could have a unique registered address and be track able from anywhere in the world via the Internet. But it's still better than having the Internet closed due to over capacity.

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