Software-Defined Networks: A Systems Approach

The Internet is the midst of a transformation, one that moves away from bundled proprietary devices, and instead embraces disaggregating network hardware (which becomes commodity) from the software that controls it (which scales in the cloud). The transformation is generally known as Software-Defined Networking (SDN), but because it is disrupting the marketplace, it is challenging to untangle business positioning from technical fundamentals, from short-term engineering decisions. This book provides such an untangling, where the most important thing we hope readers take away is an understanding of an SDN-based network as a scalable distributed system running on commodity hardware.

Anyone that has taken an introductory networking class recognizes the protocol stack as the canonical framework for describing the network. Whether that stack has seven layers or just three, it shapes and constrains the way we think about computer networks. Textbooks are organized accordingly. SDN suggests an alternative world-view, one that comes with a new software stack. This book is organized around that new stack, with the goal of presenting a top-to-bottom tour of SDN without leaving any significant gaps that the reader might suspect can only be filled with magic or proprietary code. We invite you do the hands-on programming exercises included at the end of the book to prove to yourself that the software stack is both real and complete.