Network Services SDN Part 1: What is software-defined networking?

By: Neil Alhanti

At some point in every organization’s genesis, they must make a decision about the type of network that best suits their needs. Software-defined networking (SDN) is one of the most popular modern methods for application deployment. Modern enterprises use SDN to quickly deploy their applications while simultaneously reducing operating costs and the overall deployment costs. But what is SDN and how is it different from traditional networking?

Techopedia defines SDN as a “computer network architecture [with] its main distinguishing factor [being] the separation of the data plane from the control plane in routers and switches”. For SDN, the control is incorporated into the software and decoupled from the hardware. In terms of OpenFlow, one of the most popular specifications for SDN, or similar SDN architecture, the control plane is incorporated using software from the servers and is incorporated separately from networking equipment. Opposite the control plane, the data plane is incorporated within the network hardware.

SDN uses open application programming interfaces (APIs) to support “programmatic management, control, and optimization of network resources”. When SDN decouples the network configuration and traffic and separates them from their hardware infrastructure, the decoupling creates network control. OpenFlow and other open protocols can “apply globally aware software control at the edge of the network to access network switches and routers that typically use closed and proprietary firmware”.

SDN versus traditional networking

Techopedia argues that SDN is best understood when compared with traditional networking and how traditional networking uses data packets. For traditional networking, data packets are directed from a switch or router by firmware that instructs the hardware on where the traffic loads need to go and on what path the traffic must travel to get there. Although advanced smart switches with application-specific integrated circuits (ASIC) can recognize different data packet types and treat them differently, with traditional networking most packets are treated identically.

Alternatively, SDN “decouples the control from the networking hardware’s firmware and puts it in the hands of the network administrator”. The network admin uses a central control console to direct the network traffic without altering the switches’ settings. Network admins have the flexibility to alter a network’s rules or prioritization, or even block specific packets. Techopedia notes that “SDN [is] very important for cloud computing [because it uses] multi-tenant architecture [and] allows for a more efficient and flexible control of traffic loads”.

Because it can use cheaper commodity switches and continue to provide better traffic control than traditional networking, SDN is often considered a less costly alternative to traditional networking. Network administrators and engineers “can support switching fabrics across hardware from different vendors and models [and] integrate switches with ASICs and those without”.

Ready to take the next step? Schedule a consultation with an Software-defined networking (SDN) expert.

In depth: IBM Network Services topics:

Network Services

Network Consulting Services

Software Defined Networking (SDN)

Managed Network Services

Hybrid SD-WAN Services

What is Software-defined wide area network (SD-WAN)?

What is a software-defined data center and how it can help your business?

SDN vs Traditional Networking Explained

What is network function virtualization (NFV)

About The Author

Neil Alhanti

Senior Writer, IBM Global Technology Services

Neil Alhanti is a content marketing writer, wordsmith and editor extraordinaire with IBM Global Technology Services. He spends his days crafting conversational communications across multiple mediums and otherwise “fighting the good fight and writing the good write.”