Software-Defined Networking: A Comprehensive Survey (1406.0440v3)

Abstract: Software-Defined Networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound APIs, network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms -- with a focus on aspects such as resiliency, scalability, performance, security and dependability -- as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

• The paper presents a comprehensive analysis of SDN, highlighting its shift from traditional networks to a programmable, layered architecture.
• It details innovative programming techniques and scalability strategies that enable dynamic network management through centralized control.
• The survey also addresses security challenges and future directions, emphasizing robust frameworks for resilient SDN deployments.

Software-Defined Networking: A Comprehensive Survey

Software-Defined Networking (SDN) represents a significant transformation in how networks are designed, managed, and operated, marking a departure from traditional networking paradigms. This comprehensive survey, authored by Kreutz et al., provides an exhaustive analysis of SDN, from its inception to its potential future trajectory.

Key Aspects of SDN

The paper meticulously outlines the motivations behind SDN, underscoring the limitations of traditional IP networks, particularly their complexity, rigidity, and the cumbersome nature of managing vertically integrated control and data planes. SDN addresses these pain points by decoupling the control from the data planes, enabling programmability and centralized management. This approach promises unprecedented flexibility, as network operators can dynamically adjust network behavior through software applications running on SDN controllers.

The survey explores the architectural underpinnings of SDN, describing the layered approach that separates the data plane, comprising simple forwarding devices, from the control plane, which handles complex decision-making. This structure not only enhances network manageability but also bolsters innovation, as new network functionalities can be introduced without hardware changes.

Components and Operations

The layered analysis starts with the data plane infrastructure, highlighting the rise of OpenFlow as a dominant southbound interface, followed by a discussion on network hypervisors and operating systems. SDN controllers stand out as critical elements, serving as the network's "brain" by managing state distribution and offering a programmable interface for developing network applications.

A focal point of the survey is the exploration of programming languages in SDN. These languages abstract low-level configurations into high-level constructs, empowering developers to create more robust, modular, and reusable network applications. Languages like Pyretic and Frenetic exemplify this abstraction, facilitating the implementation of complex policies with ease.

Challenges and Opportunities

The paper does not shy away from discussing the challenges faced by SDN. Scalability is a major concern, as controllers must efficiently handle massive amounts of network traffic and state information. The authors review various approaches to scaling SDN, including distributed controllers and innovative data plane strategies, to ensure SDN can meet the demands of large-scale deployments.

Security and dependability also receive significant attention, given the centralized nature of SDN, which introduces new attack vectors. The survey calls for robust security frameworks to protect SDN operations, emphasizing the need for mechanisms to ensure control plane security, data integrity, and network resiliency.

Future Directions

Kreutz et al. speculate on the potential evolution of SDN, envisioning it as an enabler for more extensive software-defined environments (SDEs) where compute, storage, and network resources are fully integrated and dynamically configurable. Such environments promise streamlined IT operations, responsive to the needs of applications and users.

In conclusion, this comprehensive survey underscores SDN's transformative potential while recognizing the critical challenges that need to be addressed to realize its full benefits. By separating control logic from hardware, SDN facilitates innovation and adaptability, laying the groundwork for more agile and efficient network infrastructures. The paper is an essential read for researchers and practitioners aiming to leverage SDN in contemporary networking paradigms.