Understanding Software-Defined Networking (SDN)

SDN, in networking terminology, stands for Software-Defined Networking. It’s a modern network architecture designed to enhance the flexibility, efficiency, and manageability of computer networks.

In traditional networking, network devices like routers and switches have their control plane and data plane tightly integrated. This makes it difficult to adapt to changing network requirements and traffic patterns.

SDN addresses this by separating the control plane from the data plane, enabling centralized control and programmability of the network. Think of it this way: traditionally, each router and switch makes its own decisions about where to send data (control plane) and then does the actual forwarding (data plane). SDN centralizes the decision-making process, allowing for more intelligent and dynamic network management.

We’ve all seen networking setups where routers, switches, and firewalls are installed based on initial network layouts. The problem arises when requirements change later on. Modifying existing networking components can be difficult, often leading to the need to replace entire devices with higher-capacity ones. Software components of traditional networking devices are often inflexible. This is where SDN comes in.

In SDN, software components can be customized and configured based on current needs. This can be done independently of any specific hardware device. Essentially, all the networking hardware can be defined and adapted by changing the software installation during deployment. This greatly helps in enhancing data flow across the systems.

The impact of SDN is most keenly felt by networking service providers and large business enterprises, rather than individual end users. However, end users ultimately benefit through enhanced services, improved security, and a seamless overall experience.

Here are the major factors driving the evolution of SDN:

• Changes in user traffic patterns and the types of networking devices being used.
• The demand for scalable storage, computing, and networking resources by large and dynamic enterprises.
• The need for massive parallel processing on servers and the increasing volume of big data flowing between them.

The shift of distributed data centers to the cloud region is considered a major motivator for SDN’s evolution.

SDN Architecture

Image Alt Text: SDN Architecture

The diagram illustrates the SDN architecture, which consists of three primary layers: the Application layer, the Controller layer, and the Data plane layer.

Traditional networks integrated the control plane, data plane, and management plane into a single networking device. In software-defined networks, the control plane and management plane are separated and consolidated into what’s known as the “controller.”

The controller communicates with the data plane using the OpenFlow protocol, which is integrated into the data plane layer through an OpenFlow API. The application layer sits on top of the controller.

Essentially, the OpenFlow protocol allows external control software (the controller) to manage the data path of a switch by using flow tables.

Here’s a breakdown of the functions of key components in the SDN architecture:

• Data Plane: This is where the actual network traffic flows, handled by switches and routers.
• Control Plane: This is the “brain” of the network, responsible for managing routing, traffic policies, and network topology.
• Application Plane: This comprises the software applications that control and manage the network using APIs provided by the control plane.

Benefits of Using SDN

A major driver for adopting SDN is that the world’s largest networks, including Google, Yahoo, Verizon, Microsoft, Facebook, NTT Communication, and Deutsche Telekom, already support SDN-based architectures.

Here are other key benefits:

• Centralized management of networking devices.
• Improved automation of network components.
• Enhanced usability for end users.
• Suitability for multi-tenancy applications.
• Multi-tenancy enables secure communication between distributed data centers serving different customers. Multiple tenants can share the same physical resources, with each tenant assigned unique logical resources.

In short, SDN delivers networks with greater flexibility, scalability, and efficiency.

SDN Standards

The ONF (Open Networking Foundation) is actively working to finalize standards for SDN.

The organization is focused on standardizing the OpenFlow Protocol, which governs communication between the control plane and the data plane. This standardization facilitates interoperability between network devices from different vendors and enables high-performance, granular traffic control.

OpenFlow-based SDN is currently under deployment.

SDN is primarily driven by user companies. More than 66 companies are collaborating to realize the vision of ubiquitous SDN and to foster a vibrant market for SDN products and services. In addition to standard finalization, the ONF is also working to educate the market, protect intellectual property, and develop an SDN architecture framework.

SDN Products

Brocade offers the MLXe 24-port 10GbE module, which, along with 100Gb Ethernet capability, enables OpenFlow for SDN on the MLXe core router.

Brocade also provides the ADX switch, which offers multi-tenancy support. This switch optimizes resource utilization by consolidating multiple devices into one.

Conclusion

In summary, the SDN architecture separates the control, data, and application planes of a network. This separation offers significant benefits, including centralized control, flexibility, network programmability, optimized traffic management, simplified management, resource efficiency, and improved security.