Software-defined networking (SDN) aims to make network architectures and supporting devices easier to manage. SDN typically relies on a centralized management platform (or control plane) that sets rules for and collects statistics from the data plane — which handles data packet delivery.
SDN is a programmatic approach that commonly uses APIs, software-as-a-service (SaaS) and infrastructure-as-a-service (IaaS) management tools, and other cloud-computing services to handle networking configurations. These software solutions integrate with other virtual layers and underlying physical devices to boost networking efficiency, security, flexibility, and high availability. It also helps organizations incorporate key business logic into their networking setups to meet business needs.
SDN also removes siloes present in other networking setups — in which routers, switches, and other components are only aware of counterparts installed within their own environments. Software-defined networking helps build bridges between clouds and datacenters, making it easier to apply sweeping changes and manage everything from one place with greater visibility.
Alternatively, SDN gives teams the option to segment their networks into virtual or physical groupings based on business unit, environment, or other factors. This helps administrators create clearer networking boundaries as needed, or bring components together that were previously separated. SDN provides the virtual layer necessary to control everything as efficiently as possible.
How does software-defined networking (SDN) work?
An SDN setup fundamentally separates the control plane (which is fully virtualized in this instance) from the data plane, which helps transmit data back and forth between physical devices. This requires a software-based controller that actively monitors a dynamic group of networking devices, whether they're being added, changed, or removed from the overall infrastructure.
Software-defined networking relies on the following components:
Applications – Networking services and other apps that communicate with the control plane, determine resource needs, and provide continual visibility into requests and the greater network
Control layer – The central SDN command center governing resource allocation, data transmission across the network, and chatter back and forth with the larger infrastructure layer
Controllers – Software agents that communicate with applications to control where data packets are flowing
Infrastructure layer – The physical networking layer (with routers and switches) that enables data transmission and traffic flows across the network
Third-party technologies – Other software components from vendors, or other internet protocols, that promote unity between SDN components while ensuring improved traffic management workflows
While SDN offers enhanced management flexibility and fine-grained control, it also deeply incorporates automation to speed up common management tasks. This helps teams handle firmware updates, software updates, infrastructure additions or subtractions, and configuration much more easily.
It's also possible to adopt SDN practices in varying ways. The first is the common API-based approach, which uses southbound APIs to provide real-time communication between controllers, switches, and other network interfaces. Meanwhile, northbound APIs enable communication between the SDN controller and applications that impact higher-level components while offering more control.
Second, open SDN uses one or more open-source protocols to control both virtual and physical networking components. This enables teams to route data packets more intentionally, and helps promote collaboration through a shared standard that everyone can use effectively.
Third, the overlay approach to SDN creates a network atop the existing network — allowing for better use of existing hardware without sweeping infrastructure changes, and splitting network resources (bandwidth, etc.) between predetermined channels. These channels are formed by tunneling into varied datacenter environments.
Lastly, it's also possible to implement a hybridized form of SDN. Each type of network traffic is handled by its own specific protocol. The process of setting up hybrid SDN is also less disruptive, as this approach still incorporates traditional networking elements and is more measured. Organizations don't have to overhaul or replace aging infrastructure to effectively use SDN.
What are the benefits of software-defined networking (SDN)?
We've touched on the abstraction, greater control, and networking flexibility afforded by SDN. However, SDN comes with other key benefits:
Network simplification, by potentially consolidating network administration operations behind a single protocol and centralized control layer. Teams can communicate with a vast array of hardware devices and choose their preferred networking components to avoid lock-in.
Improved security, via deep observability over the entire network, networking devices, and traffic flowing through them. Administrators can freely establish virtual network microsegments and boundaries to reduce exposure to (or the impact of) threats, and can quickly implement security policies.
Infrastructure modernization, by letting teams shift completely to a virtualized, software-defined networking environment — or transition at their own pace through hybridization or an overlay network
Does HAProxy support software-defined networking (SDN)?
Yes! HAProxy One — the world's fastest application delivery and security platform — seamlessly blends data plane, control plane, and edge network to deliver the world's most demanding applications, APIs, and Al services in any environment.
HAProxy Fusion also provides a single pane of glass for managing multi-cloud, and multi-team HAProxy Enterprise deployments. This is possible programmatically via a REST API with 100% coverage or an intuitive GUI.
Organizations are already using HAProxy to power their SDN infrastructure. To learn more about SDN support in HAProxy, check out Nokia's HAProxyConf 2021 talk: Enabling SD-WAN Operations Using HAProxy.