Navigating the Complex World of Software-Defined Networking: An Overview

Author: Kayla Stockdale/Tuesday, January 2, 2024/Categories: Business Internet

Software-defined networking (SDN) has transformed the way businesses manage their networks, offering potential time and resource savings by separating network configuration and traffic engineering from the underlying hardware. This article provides an overview of SDN, discussing its benefits, components, types and comparisons to traditional networking and software-defined wide area networking (SD-WAN). 

Additionally, this article explores why Consolidated Communications is a reliable and cost-effective partner for businesses seeking to harness the advantages of software-defined networking. With a deep understanding of traditional networking data plane, control plane and management plane, as well as various SDN models such as Open SDN, API SDN, overlay model SDN and hybrid model SDN, this article serves as a comprehensive guide to navigating this intricate technology. 


  • Software-defined networking (SDN) is an architectural model that separates network configuration and traffic engineering from the underlying hardware. 

  • Businesses can capitalize on software defined benefits through improved scalability, cost savings, enhanced visibility and control, increased flexibility and rapid deployment of new applications and services. 

  • Consolidated Communications offers reliable services and advanced network management to capitalize on the potential of SDN. 

What is software-defined networking? 

SDN is a network architectural model that enables programmatic control, management and optimization of network resources, leading to faster and more efficient operations. Unlike traditional networks, which rely on dedicated hardware devices for controlling network traffic, SDN employs software-based controllers or application programming interfaces (APIs) to communicate with the underlying hardware infrastructure to direct traffic flow on a network. This separation of network configuration and traffic engineering from the underlying hardware infrastructure provides greater flexibility and control over network operations. 

Despite its widespread adoption and clear advantages, some misconceptions regarding SDN persist. For example, it is often assumed that organizations must entirely replace their existing network infrastructure with new hardware and software resources to implement SDN. In reality, organizations can start with specific SDN use cases, and SDN simply restructures the architecture to allow for centralized control and multiple levels of automation across the network. 

Why do businesses need software-defined networking? 

SDN offers several advantages over traditional networking, including the ability to respond quickly and effectively to changing network requirements and the automation of network management tasks, resulting in cost savings and improved scalability. With the centralized control provided by SDN, businesses can gain greater visibility and control over their networks, enabling rapid identification and resolution of any arising issues. 

Furthermore, SDN allows businesses to design their networks according to their specific requirements and quickly deploy new applications and services. The Open Networking Foundation (ONF), a consortium of enterprises, service providers, developers and vendors, works to advance the development of SDN standards and ensure that SDN solutions are compatible and vendor-agnostic. 

Understanding traditional networking 

Traditional networking involves three distinct planes: the data plane, control plane and management plane, which work together to manage traffic, transmit data and configure network devices. 

The data plane forwards and processes data packets based on configurations provided by the control plane. The control plane dictates the forwarding behavior of routers, while the data plane carries out the actual forwarding as instructed by the control plane. 

Packet forwarding occurs in the hardware of a router, specifically in the data plane. The management plane is used to configure and monitor network devices. 

Data Plane 

The data plane in SDN is responsible for forwarding and processing data packets based on configurations provided by the control plane. In other words, it carries user traffic. 

In traditional networking, the data plane primarily forwards packets. In SDN, the data plane forwards and processes data packets according to the instructions provided by the control plane, using a combination of mobile devices, network virtualization and underlying hardware infrastructure. This allows for the separation of control and data planes. 

Control Plane 

The control plane in SDN is responsible for managing network traffic flows and defining traffic routing and network topology. It is implemented in software and decoupled from the data plane, which physically handles the traffic based on the configurations supplied from the control plane. 

The control plane in traditional networking is tasked with making decisions regarding the forwarding of packets. The control plane in software-defined networking is implemented in software and is distinct from the data plane. It is responsible for defining traffic routing and network topology, as well as managing network traffic flows. 

The data plane then carries out the configurations supplied by the control plane to physically handle the traffic. 

Management Plane 

The management plane in traditional networking is tasked with configuring and overseeing network devices. The management plane is an integral part of a networking device or system, providing essential management, monitoring and configuration services to all layers of the network stack and other parts of the system. 

In the context of SDN, the management plane is used to configure and monitor network devices. This includes manual processes, such as setting up network policies, as well as automated processes, such as centralized control and global view of the entire network. 

Through the management plane, network administrators are able to manage the network’s resources, behavior, traffic and state. 

How does software-defined networking work? 

SDN is a new approach to networking that enables greater programmability, flexibility and agility. SDN is based on the concept of separation of planes, which involves the division of the control plane from the data plane. This separation enables the network to quickly and efficiently adapt to changing business requirements and end-user needs, while safeguarding existing investments. In addition to its separation of planes, SDN also leverages three primary layers — an application layer, control layer and infrastructure layer — as well as northbound and southbound APIs. 

Application Layer 

The application layer of SDN is tasked with bridging the gap between traditional network architecture and SDN, thus enabling the realization of tangible business benefits through improved performance. 

Control Layer 

An SDN controller is a key component of the SDN control plane, providing a communication interface between the network elements and the network-control applications. It’s tasked with preserving the network-state, which encompasses data related to the status of hosts, links, switches and other controlled elements in the network. 

The utilization of distributed servers offers numerous benefits, such as fault tolerance, high availability and improved efficiency. This enables the network to be managed more effectively, as well as providing the necessary security and scalability for a modern network. 

Furthermore, distributed SDN controllers provide a logically centralized control plane, allowing network administrators to easily manage and monitor network behavior. 

Infrastructure Layer 

The infrastructure layer of software-defined networking is composed of networking devices that manage the forwarding and data processing capabilities of the network. These devices include switches, routers, servers and storage devices, which are responsible for the processing of control data and the forwarding of data. The infrastructure layer is essential to the functioning of the SDN architecture, as it provides a platform for the control plane and management plane to communicate with each other, while also offering a layer of abstraction between the underlying hardware infrastructure and the rest of the network. By providing network administrators with an unparalleled level of control and flexibility over the entire network, the infrastructure layer serves as the foundation for a truly intelligent network. 

The infrastructure layer is also responsible for the implementation of network virtualization and the deployment of network functions virtualization (NFV). This allows network operators to achieve the performance, scalability and cost savings associated with a software-defined network, while also ensuring that network policies, traffic engineering and network resources are all managed efficiently. Through the utilization of network topology, network control and network intelligence, the infrastructure layer provides the basis for dynamic control and optimization of the network, enabling network administrators to quickly and easily adjust the design of the network according to changing business requirements and end-user needs. 

Northbound APIs 

Northbound APIs are the interface between applications and the SDN controller in software-defined networking. These APIs enable applications to communicate their requirements to the network and receive resources in return. An example of a Northbound API is a REST interface, which provides a secure and easy-to-use method for applications to access the SDN controller and configure the network according to their needs. By utilizing Northbound APIs, applications can quickly and easily access the network and utilize the resources available to them. 

In addition to providing applications with access to the network, northbound APIs can also be used to quickly and easily deploy new services to the network. These services include network services such as load balancing, application-level routing and quality of service. By leveraging the power of northbound APIs, network administrators can quickly and easily deploy new services, allowing them to keep up with the ever-evolving needs of the business. 

Southbound APIs 

Southbound APIs are interfaces used within SDN to enable communication between the SDN controller and the switches and routers within the network. Through these APIs, the SDN controller can make dynamic changes to the network in response to real-time demands and needs. 

The communication layer in SDN is a protocol that enables the SDN controller to communicate with the network elements, and southbound APIs are employed to facilitate this communication. These APIs enable the SDN controller to quickly and easily configure the network according to the needs of the business, thus allowing the network to dynamically adapt to changing requirements. 

Southbound APIs also enable the SDN controller to quickly and easily deploy new services to the network, such as load balancing and application-level routing. This ensures that the network is able to keep up with the ever-evolving needs of the business. 

Types of software-defined networking 

SDN is a form of computer networking that utilizes software abstractions to control and manage network resources. It is a network architecture that has revolutionized the way networks are designed and operated. There are four main types of SDN available: open SDN, API SDN, overlay model SDN and hybrid model SDN. 

Open SDN 

Open SDN is an approach to software-defined networking that utilizes open-source technologies and standards, enabling the programmability of the control plane and the abstraction of the application and networking services in the infrastructure. This is achieved by separating the network control and the forwarding functions in the architecture. 

Open SDN offers a range of benefits, including increased flexibility, scalability and agility in network management, as well as cost reductions and the capacity to integrate with other open-source technologies. OpenFlow, Open vSwitch and OpenDaylight are examples of open SDN technologies. They provide network topology, network control and network virtualization capabilities, allowing network administrators to programmatically configure and manage their networks. 


API SDN is a software-defined networking approach that utilizes APIs to enable network administrators to programmatically provision and manage networks from a remote location. This approach offers benefits such as increased efficiency and decreased risk of errors associated with manual configuration, as well as the ability to quickly respond to changing network conditions. 

An example of API SDN in action is the automation of the setup of network devices, such as switches and routers, through the utilization of scripts that interact with the APIs provided by the network devices. Additionally, APIs can be used to create a virtualized network layer on top of the physical network, allowing for the implementation of applications or policies that control the behavior of the network. This approach provides the potential for new applications and enhanced security benefits. 

Overlay model SDN 

An overlay model SDN is a software-based approach to creating virtualized network layers on top of a physical network. This method provides the potential for new applications and enhanced security benefits. 

The overlay model SDN utilizes software to construct layers of network abstraction, allowing for the implementation of multiple, distinct virtualized network layers on top of the physical network. This approach offers a range of potential benefits, such as increased flexibility, scalability and agility in network management, as well as cost reductions and the capacity to integrate with other technologies. 

Examples of overlay model SDN in operation include VMware NSX, Cisco ACI, and Juniper Contrail. 

Hybrid model SDN 

The hybrid model of SDN combines the advantages of traditional networking protocols with the flexibility of SDN, creating an environment that allows for both centralized and distributed control planes. This approach offers the best of both worlds, providing the robustness of traditional protocols with the agility of SDN. A hybrid model of SDN offers the advantage of flexibility from SDN while maintaining the reliability of traditional protocols. This provides greater control over the network and the capacity to adjust to fluctuating network conditions. Additionally, it can be more straightforward to integrate with existing infrastructure. 

A hybrid model of SDN can be beneficial in large enterprise networks requiring both centralized and distributed control planes. Additionally, it can be advantageous in situations where integration with existing infrastructure is necessary, or when legacy devices cannot be replaced. 


SDN and software-defined wide area networking (SD-WAN) are two distinct software-defined networking solutions. SDN provides increased flexibility and scalability for internal networks, while SD-WAN offers improved performance and cost efficiency for wide-area networks. SDN architecture decouples the control plane from the data plane, enabling simpler network administration and automation. 

SD-WAN is a software-defined solution for managing a wide area network (WAN), providing improved performance and cost-efficiency. The primary distinction between SDN and SD-WAN is that SDN is primarily concerned with the internal network infrastructure, while SD-WAN focuses on external network connections. 

SDN is advantageous as it enables businesses to deploy and manage network services faster, more securely, and more efficiently. On the other hand, SD-WAN is beneficial for businesses as it allows for more efficient utilization of multiple network connections, diminishing the necessity for costly dedicated WAN links. 

Business adoption vs. traditional networking 

Businesses can leverage the benefits of SDN to enhance network security, automate network management processes and optimize network performance. For instance, businesses can use SDN to automatically reroute traffic in the event of a network disruption or to prioritize network traffic based on specific applications or users. 

SDN can also boost network performance by enabling businesses to prioritize network traffic according to specific applications or users, as well as providing centralized management and provisioning of network services. Furthermore, it facilitates automation at scale through a single interface, allowing businesses to quickly adjust to changing network requirements. 

Why Consolidated Communications? 

Consolidated Communications is a provider of fiber communications and networking services for businesses. We offer a wide range of services that help businesses simplify their network management and provisioning, making it easier to scale their networks to meet their business needs. We also provide reliable, top-notch services and advanced network management through automated testing and active data-plane measurements. This helps to ensure businesses are able to get the most out of their networks while keeping costs down. We deliver great solutions for clients looking to take advatage of software-defined networking benefits. 


Through this overview of SDN, it is evident that migrating from traditional networking to SDN has the potential for major positive impacts for businesses. Implementing an SDN offers advantages over traditional networking, such as improved scalability, cost savings, greater visibility and control and the ability to quickly deploy new applications and services. 

The main distinction between SDN and SD-WAN is that while SDN focuses on managing internal networks, SD-WAN focuses on external connections. If you are a business considering adopting an SDN solution, Consolidated Communications can provide top-notch services and long-term reliability via automated testing and active data-plane measurements specifically suited to taking advantage of the benefits of software-defined networking. 

Ultimately, businesses can leverage SDN to improve current operations and optimize their future investments. 

Frequently Asked Questions 

What are the three layers of SDN? 

The three layers of SDN architecture are the application layer, the control layer and the infrastructure layer. These layers communicate through northbound and southbound APIs to provide an efficient and cost-effective approach to managing networks. 

What are the four key characteristics of an SDN architecture? 

SDN architecture provides four key advantages: a centralized control plane, programmability and flexibility, open APIs and improved scalability and manageability. 

These features enable network administrators to effectively manage modern networks and facilitate rapid development of new services. 

What are the key concepts of SDN? 

SDN is a technology that allows organizations to manage their networks more easily and cost-effectively. SDN offers improved flexibility, increased scalability and optimized traffic flows. As a result, organizations can better manage and secure their networks, allowing them to reduce costs and increase efficiency. 

What is the core idea of software-defined networking? 

SDN is a revolutionary approach to network infrastructure that separates the network's control plane and data plane functions. This allows it to be programmed so that the entire network switch, server and even application can be managed centrally, enabling dynamic, agile traffic flows and on-demand scalability. 

SDN provides a number of advantages over traditional networking, including improved scalability, increased flexibility and reduced complexity. It also allows for more efficient use of resources, as well as improved security and reliability. With SDN, the network can work. 


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