IPv4 and IPv6: What They Are and Why They're Important

IPv4 address with dotted decimal notation

Indeterminate [Public domain] / Wikimedia Commons

Perhaps you've read that IPv4 has run out of addresses and that the new IPv6 is going to solve the problem. Here's why.

How Internet Addressing Works

Every device that connects to the internet needs an address, much like the address for a house or business. With Internet Protocol addresses (IP addresses) you will eventually run out of unique addresses — a bit like running out of land for building new houses, to continue the metaphor. With IP addresses, there is a mathematical limit to how many different addresses are possible for internet devices. The original internet addressing system is called Internet Protocol version 4 (IPv4), and it has been assigned to computers and networks on the internet successfully for many years. By employing 32 bits of recombined digits, IPv4 has a maximum of 4.3 billion possible addresses.

An example of an IPv4 address is

Despite this seemingly enormous number of addresses, the rapid growth of the internet began to rapidly use up those addresses. There are not enough IPv4 addresses to accommodate all of the computers, smartphones, mobile devices, and other things that have proliferated since the beginnings of the internet.

IPv6 Brings Good News

A new internet addressing system, known as IPv6, has enlarged addressing system to help address the limitation of IPv4. IPv6 uses 128 bits instead of 32 bits for its addresses, creating 3.4 x 1038 possible addresses — trillions and trillions of addresses. However, the Internet Assigned Numbers Authority has only apportioned some of these for public addresses. There's no shortage of them, but all 340 undecillion aren't technically available, just 42 undecillion. These trillions of new IPv6 addresses will meet the internet demand for the foreseeable future.

An example of an IPv6 address is 3ffe:1900:4545:3:200:f8ff:fe21:67cf.

When Is the Switch to IPv6?

screenshot of chart showing Google IPv6 Adoption

The world has slowly begun to embrace IPv6, and those addresses coexist alongside the older IPv4 addresses. Big web properties like Google and Facebook officially began to switch in June 2012. Other organizations have been a bit slower. Google tracks IPv6 adoption, and the statistics show that there's still a ways to go.

The change to IPv6 has been largely invisible to most computer users because it has occurred primarily behind the scenes. It doesn't require the average user to learn anything new. New computers and devices like smartphones are making the change and eventually when upgrading your technology, it'll be taken care of.

What Will Happen to IPv4?

IPv4 addresses aren't going away any time soon. Those addresses are still in use, and though we have exhausted the supply of new ones, older ones can still be bought and sold. Perhaps one day, adoption of IPv6 will reach 100 percent and there will no longer be any IPv4 addresses in use, but that day is likely still in the distant future.