Why IPv6?

This is an interesting question. IPv6 buys you only a bit more than you already have today; and most of that is a promise. IPv6 will help you preserve the level of Internet connectivity between your home and other locations on the Internet, without interference, as you enjoyed in 2012.

The promise is the ability to give every device in your house a reachable network address. Each house will have practically unlimited network addresses (2⁶⁴ if you're curious - about 18 billion billions). Each house may potentially have more than that, particularly if they have the need for multiple networks within the home. Many ISPs will be able to easy give you 256 of those networks. Running out of IPv6 address space will seem impossible for decades.

Applications to take advantage of this are just now being thought of. Imagine having all of your home electronics accessible from work or from your mobile phone. You could watch your TV recorder, or the security camera. You could check the fridge, perhaps start the oven timer. Maybe turn on the air conditioning or the heater when you know you're coming home early. All of these *can* be done today, but are cumbersome with IPv4 if you're using a single IPv4 address today. And, very difficult in the future, with where IPv4 is heading next.

What Is Wrong with IPv4

The traditional IPv4 Internet is running out of space. The IANA registry (at the global level) is either just about out, or totally out, depending on when you read this. They are expected to announce this depletion Janaury or February 2011.

As Internet service providers each run out of the space they have been allocated, they will have to find creative ways to help keep taking on new customers. Those customers will still need access to the IPv4 Internet.

Q: I heard there are millions of addresses left. Take it back from the companies not using it! Use the Class E space! (etc).

Those have been looked at. The space is relatively small, given the rate that the world is consuming it now. Forcefully taking back space would require more time in the court systems than it would buy back. Other currently reserved space is too difficult to use - it would require replacing most of the routers in the world to do so.

Q: What creative ways will ISPs keep IPv4 running?

Most commonly, some form of NAT. NAT is a form of address sharing; think of it as a party line from the earlier days of the telephone. You'll be able to make outgoing connections easy enough, as long as your shared IP address is not too busy.

Note this is in addition to any NAT you do at home.