This book will cover structure, behavior and fields, all of which will be supported by packet captures and analysis. This second installment will cover layers 2 and 3 and is concerned with the key protocols and operations. It is meant to be a follow up to the first book in the sense that these are more advanced ideas that assume and/or build on the previous ideas. For example, it is difficult to understand routing without first understanding IP. This book will be written to a depth that will serve experts and those first learning about these topics.