IPv6 And Really Large Numbers

Previously: First Rumbling Of The Coming IPv6 Transition

In the early 90s, a bunch of smart people in a position of authority got together and put together a replacement for IPv4 named IPv6, after many committee meetings and a few false starts. Since the immediate issue was the shortage of numbers looming on the 20-year horizon, let’s look first at what they came up with to make sure we wouldn’t run out again.

Recall that there are 2³² possible IPv4 addresses, or about 4.3 billion addresses. With IPv4, a single address is assigned to a particular device at a particular time and we ran out because more people wanted more devices than anyone anticipated. The new scheme had to have enough addresses to accommodate all the mobile phones or smart refrigerators or whatever for a long time to come.

The Internet Engineering Task Force decided to err on the side of hugeness and decided the new address space would have 2¹²⁸ addresses.

Let’s look at how many addresses that is.

This is my favorite picture. The picture and descriptions are from this article about IPv6.

A (Poor) Representation of Relative IPv4 and IPv6 Address Space Sizes

I wanted to make a cool graphic to show the relative sizes of the IPv4 and IPv6 address spaces. You know, where I’d show the IPv6 address space as a big box and the IPv4 address space as a tiny one. The problem is that the IPv6 address space is so much larger than the IPv4 space that there is no way to show it to scale!

To make this diagram to scale, imagine the IPv4 address space is the 1.6-inch square above. In that case, the IPv6 address space would be represented by a square the size of the solar system.

. . .

It’s pretty hard to grasp just how large this number is. Consider:

• It’s enough addresses for many trillions of addresses to be assigned to every human being on the planet.
• The earth is about 4.5 billion years old. If we had been assigning IPv6 addresses at a rate of 1 billion per second since the earth was formed, we would have by now used up less than one trillionth of the address space.
• The earth’s surface area is about 510 trillion square meters. If a typical computer has a footprint of about a tenth of a square meter, we would have to stack computers 10 billion high blanketing the entire surface of the earth to use up that same trillionth of the address space.

A couple more:

Wikipedia: It’s 2⁵² addresses for every observable star in the known universe.

Random bogger: We could assign an IPv6 address to every atom on the surface of the earth – and have enough addresses left over for another hundred earths.

It’s a lot of addresses. We won’t run out. Whatever else happens, we won’t run out.

The problem is, IPv6 is not particularly compatible with IPv4. Traffic running on IPv6 equipment is invisible to IPv4 equipment in almost every way. The committee made a decision not to pursue backward compatibility, which probably made a lot of technical issues easier but leaves us with difficult problems now that we’ve procrastinated and there’s no time to ease into things. It’s going to take equipment changes up and down the line, from the largest ISPs and global routers down to your office, before we will be able to deal with IPv4 and IPv6 traffic at the same time. No one knows whether that will be important to those of us in small businesses or not; that will evolve from all the confusion over our heads in the next few years. With luck, a working connection will be delivered to us, we’ll buy some new Netgear equipment, and someone else will have gone prematurely grey to make it work easily for us.

The incompatibility also explains some of the procrastination. The first people to implement IPv6 to deliver web services won’t have anybody to talk to. IPv6 can only travel on network equipment designed for it, and nobody has an incentive to go first. Google has actually gotten started, but they’re making a lonely effort so far.

You might already have your first piece of IPv6-enabled equipment: Windows 7 and Vista understand IPv6 out of the box. At the moment nothing is talking to your network adapter using IPv6 but you’ll see it listed there, waiting, on your new computer.

What is certain is that nothing you know about networking will be the same. Every concept is new in IPv6. Addresses look like this:

Various parts of that are meaningful, other parts aren’t. Assignment of addresses will be handled entirely differently, with addresses flying all over the place and routers being discovered in entirely new ways. There’s no DHCP, no Network Address Translation; get ready for Stateless address autoconfiguration, which I’m sure will be much fun as it sounds. Devices will have several addresses simultaneously, used for different purposes, and addresses will be changing constantly.

This is not news and a lot of people have already invested huge resources in the coming transition. It’s probably telling that The Pirate Bay, the best-known torrent tracker for pirated videos and music, implemented IPv6 two years ago. If the pirates are thinking about this, you know a lot of other people are too. Don’t forget there is much more pressure in other parts of the world where IPv4 addresses are already in short supply. China has set up a national IPv6 network called the “Chinese New Generation Internet. ” European car manufacturers have agreed to implement IPV6 in their cars as the standard protocol for car applications. There’s much more happening around the world.

Your takeaway? Be alert. I don’t expect this to directly affect you for years but that might not be obvious as the hubbub grows. You will eventually wind up with new networking equipment in your small US business but you don’t need to begin planning your budget yet. If you do any kind of tech support, it’s time to start reading and listening to podcasts and absorbing new vocabulary; from our perspective, it’s barreling down like a locomotive, and we’re the people who will be expected to understand it all.