Software-Defined Networking 2

1Toward a Decentralized SDN Control Architecture: Overview and Taxonomy

1.1. Introduction

In contrast to the decentralized control logic that underpins the construction of the Internet as a complex bundle of box-centric protocols and vertically integrated solutions, the software-defined networking (SDN) paradigm advocates the separation of the control logic from hardware and its centralization in software-based controllers. These key tenets offer new opportunities to introduce innovative applications and incorporate automatic and adaptive control aspects, thereby easing network management and guaranteeing the user’s QoE.

However, despite the interest surrounding SDN, adoption raises many challenges, including the scalability and reliability issues of centralized designs that can be addressed with the physical decentralization of the control plane. However, such physically distributed but logically centralized systems bring an additional set of challenges.

This chapter presents a survey on SDN with a special focus on distributed SDN control. In section 1.2, we start by describing the promises and solutions offered by SDN compared to conventional networking. We also elaborate on the fundamental elements of the SDN architecture.

Then, we expand our knowledge of the different approaches to SDN by exploring the wide variety of existing SDN controller platforms. In doing so, we intend to place a special emphasis on distributed SDN solutions and classify them in two different ways. ...