Chapter 1. The Roots of Link State Protocols

It's a terrible way to start off a book: telling you that you can skip this first chapter if you want to. If all you care about is the technical aspects of OSPF and IS-IS, proceed directly to Chapter 2: The little technical content in this chapter is not prerequisite reading. Nonetheless, I'm compelled to tell the story of link state protocols for the very simple reason that one of the few subjects I love more than networking technology is history. The study of history is essential for understanding our world and culture, and for avoiding being hoodwinked by marketeers, politicians, and other nefarious characters who would like to sell us something other than the truth. So too with technology. Knowing how a protocol works is fine, but knowing the history of the protocol deepens your understanding of it and helps you put it in a larger context. That in turn might make choosing the right protocol for your network easier. If nothing else, history is just so much more entertaining than fiction.

The history of link state protocols is inextricably intertwined with the history of the Internet and its predecessor, the ARPANET. The emergence of these large-scale networks drove the need for and evolution of link state protocols. So, this chapter is really a brief history of the Internet and how OSPF and IS-IS fit into it.