Preface

As Charles Dickens wrote in A Tale of Two Cities, "It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness." These seemingly contradictory words perfectly describe the chaos and mood felt during a time of change and transition. We are no doubt experiencing a similar time with the rapid changes in the field of network engineering. As software development becomes more integrated into all aspects of networking, the traditional command line interface and vertically integrated, network stack methods are no longer the best ways to manage today's networks. For network engineers, the changes we are seeing are full of excitement and opportunities and yet are challenging, particularly for those who need to quickly adapt and keep up. This book has been written to help ease the transition for networking professionals by providing a practical guide that addresses how to evolve from a traditional platform to one built on software-driven practices.

In this book, we use Python as the programming language of choice to master network engineering tasks. Python is an easy-to-learn, high-level programming language that can effectively complement network engineers' creativity and problem-solving skills to streamline daily operations. Python is becoming an integral part of many large-scale networks, and through this book I hope to share with you the lessons I've learned.

Since the publication of the first and second editions of this book, I have been able to have interesting and meaningful conversations with many of the readers of the book. I am humbled by the success of the first two editions and took to heart the feedback I was given. In this third edition, I tried to incorporate many of the newer libraries, update existing examples with the latest software and newer hardware platforms, and added two more chapters that I think are important for today's network engineers.

A time of change presents great opportunities for technological advancement. The concepts and tools in this book have helped me tremendously in my career, and I hope they can do the same for you.