IPv6 : Internet Protocol Version 6

Got a bad sore throat going on for a week. Certainly drank my share of hot beverages. Hoping one last tea will do the trick.

For the last decade, widespread use of IPv6 has always been "just a couple of years away". It never happened. But now things may really start to change, as the IPv4 address space is finally being exhausted.

Today's Internet runs on IP version 4, or IPv4. Every device on the Internet gets a unique IPv4 address (with some exceptions I'll mention below). IPv4 addresses are four bytes - or 32 bits - long, and are typically written like this: 98.137.10.42. Since it's a 32 bit number, the total number of IPv4 addresses is 2^32, or about 4.3 Billion (4,294,967,296 to be exact). But, there are currently over 6.7 Billion people on the Earth, so you can see right away there aren't enough IPv4 addresses to go around.

Of course, not everyone is on the Internet, but many people are consuming multiple addresses (e.g. one for the cell phone, one for their Kindle, one for their PC, etc..). There are also many IPv4 address ranges that are reserved as private addresses, so aren't available in the public pool.

The situation is helped a little by allowing multiple devices to share one public IP address. If you have a home router, and four PCs connecting through that router, then you are really only using up a single public IPv4 address because the router is running a protocol called Network Address Translation (NAT). NAT allows all four PCs to share a single public address assigned to the router. So this helps with conserving the number of IPv4 addresses being used, but even with NAT, the number of IPv4 addresses available for allocation is dwindling.

Current projections from the IPv4 Address Report site show IPv4 addresses being exhausted in March of 2011.

What then?

The answer is IPv6. IPv6 addresses are 128 bits long. That gives you 2^128 addresses, which is a *lot* of addresses. The only problem right now with IPv6 is that not every device or web site is setup to use it. All modern operating systems already have "dual stack" support - that's a networking stack with both IPv4 and IPv6 sitting side by side. But the IPv6 stack might not be configured, or you might be connecting to an ISP that's not ready to hand out IPv6 addresses, or you might have a home router that just does not have IPv6 support.

The bottom line is if you were on an IPv6 only device right now, you could only see a part of the web - the parts that are already IPv6 ready. That situation will have to change in the coming years, once the IPv4 address range is completely used up, and more and more users are only connected via IPv6.