Perfection, of a kind, was what he was after.
Epitaph on a Tyrant, W.H. Auden
In this chapter we'll cover the features of IPv6 and the basics of its design. This will be a quick tour, addressing the topics of immediate relevance to those using or about to use IPv6. Our intention is to present the information in an easy-to-understand overview format first, and then to get down to the juicy details later in Chapter 4 and Chapter 6.
When we talk about networking protocols in general it's important to understand the difference between specification and implementation. Specifications are written in IETF RFCs and are hotly debated. Implementations are prepared to those specifications, generally by coders or systems people. If you had to choose which one of these to get right, it should of course be the specifications. Broken implementations that misbehave or don't interoperate can always be rewritten, or even gradually refined; but if your design is inherently broken, you might as well throw away all your work and start again. Since (at the time of writing) we are in a relatively early stage of adoption, we expect that implementation quality will vary across different stacks, but the design is definitely right. Lessons learned during the last few decades of networking have been incorporated into the architecture of the protocol, and so the existing problems with IPv4 have been addressed. In fact, some of the problems with IPv4 will ...