Networking book review — Interconnections, Second Edition

Before I finally got around to reading it, Interconnections was something of a legend to me. I had heard it referenced several times, and I knew all about Radia Perlman as one of the pioneers of the Internet.

I love this book. This book is as much a must read for all network operators as just about anything out there. Radia Perlman is not only brilliant, her writing is fun and she was a big part of many emerging technologies that made the Internet possible. This book does a wonderful job of satiating my needs for deeply technical information about networking and the tumultuous history of the internet. Two things in which I’m endlessly fascinated.

First off, Dr. Radia Perlman. She invented the Spanning-Tree algorithm. By herself. In a day. Spanning-Tree made it possible to link ethernets together, and it was plug-and-play to boot. Think about the implications of that.

But Interconnections is not 500 pages about Spanning Tree. Perlman delves into several protocols, standards and algorithms that she worked on or that were swirling around in the 1980s and 90s. In fact, she worked primarily on Layer3 routing when her manager gave her the task that ultimately culminated in the invention of STP.

Throughout the book, Perlman covers routing fundamentals that are still used today in all popular routing protocols. She deftly takes us through network layer addressing, using several examples to explain the concepts. And that’s what I love about her style of writing and teaching. For example, to explain network addressing she doesn’t just teach you how IP handles addressing. She will teach you how addressing works with IPX, CLNP, AppleTalk and DECnet as well. So to teach a concept, she shows you how it’s been deployed in several different implementations. This also shows the reader that because IP pretty much “won”, it doesn’t necessarily mean it was the best choice, or had the best options or was even the better protocol overall. It lays out each protocol details and leaves it up to the reader to ascertain.

Aside from her story about how she came up with Spanning-Tree and the events surrounding that (and her famous poem), I was particularly interested to learn about the policies and decisions behind what came to be watershed moments with the invention and implementation of the early protocols that make up the Internet today. In particular, the decision made in 1992 to move forward with IP over the likely superior CLNP is a fascinating tale. The years wasted moving in one direction over another — and trying to wonder how much further ahead we may be today if different decisions were made. In many cases, Radia Perlman advocated for the right approach — only to find the other approach was ultimately chosen. I won’t go into all the details, the book is full of great stories.

I would also suggest this, for those starting out in networking. If you really want to understand the difference between a bridge, switch and router — this is the book. The actual answer may surprise you.

Even a seasoned network professional will learn something new from this book. It was one of the funnest and most informative technical books I’ve ever had the pleasure of reading.