IPv6 is destined to be the future of the Internet Protocol, and due to IP's critical importance, it will form the basis for the future of TCP/IP and the Internet as well. In fact, it's been under development since the middle of the last decade, and a real IPv6 internetwork has been used for testing for a number of years as well. Despite this, many people don't know much about IPv6, other than it's a newer version of IP. Some have never even heard of it at all! We're going to rectify that, of course—but before we delve into the important changes made in version 6 to how IP addressing, packaging, fragmentation and other functions, let's start with a “bird's eye” view of IPv6.

In this section I provide a brief higher-level overview of IPv6, including a look at how it differs from IPv4 in general terms. I begin with a brief overview of IPv6 and why it was created. I list the major changes made in IPv6 and additions to the protocol from the current version. I also explain some of the difficulties associated with transitioning the enormous global Internet from IPv4 to IPv6.