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Understanding Software Defined Networking (SDN), the Transformation of Traditional Networking Architecture

November 16, 2021

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The Software Defined Network (SDN) technology recently celebrated a decade since its market launch. The concept first introduced by Martin Casado at Stanford University has materialized into a solutions market that is expected to reach USD 35.6 billion by 2026. Understanding the Software Defined Network (SDN) technology is a must, in a world where quickly responding to changing business requirements has become the norm.

What is SDN?

SDN’s origins can be traced to a research collaboration between Stanford University and the University of California at Berkeley that ultimately brought forth the OpenFlow protocol. 

IBM defines SDN as “the decoupling of the network control logic from the devices performing the function, such as routers, which control the movement of information in the underlying network”

This approach simplifies the management of infrastructure, which may be specific to one organization or partitioned to be shared among several. SDN features controllers that overlay above the network hardware in the cloud or on-premises, offering policy-based management. Technically speaking, the network control plane and forwarding plane are separated from the data plane (or underlying infrastructure), enabling the organization to program network control directly, IBM experts state in a blog post.  

This differs significantly from traditional data center environments. In a traditional environment, a router or switch, whether in the cloud or physically in the data center, will only be aware of the status of network devices adjacent to it. 

Unlike traditional network architectures, where networking equipment makes traffic routing decisions on an “individual” basis, software-defined networks are designed to act in an orchestrated and unified way, managed through a centralized control console. This allows network administrators to route and modify traffic according to the needs of each application and service without having to write scripts and enter them via the CLI on each individual switch and router.

Why organizations are adopting this approach 

The massive increase of mobile devices and content, server virtualization, and the advent of cloud services are among the trends driving the networking industry to reexamine traditional network architectures.

SDN technology quickly became a must for organizations that integrate and use multivendor cloud services, operate in hybrid cloud environments, and those using containerization platforms or hyper-converged solutions. But SDN is not only necessary for these categories of companies, but also for those who want to improve network performance and efficiency, increase the agility of their management teams, gain rapid access to new control and analysis functionality, ensure higher levels of service flexibility, and availability and achieve CapEx and OpEx savings.

These are attractive benefits for any company, and the preconception that this type of solution is useful and accessible only to telecom operators, large service providers or cloud providers is rapidly eroding. The market has already understood that SDN solutions have reached the maturity level that allows them to generate real gains, which can be seen in the accelerating adoption rate. 

Critical areas in which SDN technology can make a difference for an organization

Until a few years ago, network services were provided by a few specialized service providers whose operations were based on network devices that were very similar to early computers’ architecture: boxes that could not be modified and were guarded by proprietary laws. Such infrastructure was very slow to adopt innovations, and only those functionalities that had been implemented by vendors could be used. SDN completely changed the system and transformed the traditional networking architecture.

As the SDN movement represents a major change in the networking world, there are a few critical areas in which SDN can make a difference for an organization. 

First of all, SDN accelerates business innovation by allowing network operators to program and reprogram the network in real-time to meet specific business needs and user requirements as they arise. Applications will interact with the network through APIs, instead of management interfaces tightly coupled to the hardware. 

Another benefit of SDN refers to network management and visibility. As SDN enables network behavior to be controlled by the software that resides beyond the networking devices that provide physical connectivity, network operators can tailor the behavior of their networks to support new services and even individual customers. For example, the flow-based control model allows managers to apply policies at a very granular level, including the session, user, device, and application levels, in a highly abstracted, automated fashion.

Finally, SDN architectures embrace a new era of openness, enabling multivendor interoperability. The open APIs support a wide range of applications, including cloud orchestration, OSS/BSS, SaaS, and business-critical networked apps. In addition, intelligent software can control hardware from multiple vendors with open programmatic interfaces like OpenFlow. 

Tech trends such as server virtualization, IT-as-a-Service, cloud computing, and the Internet of Things exposed the fact that today’s conventional network architectures can’t handle the challenges. Software Defined Networking provides a new, dynamic network architecture that transforms traditional network backbones into rich service-delivery platforms. If you consider implementing SDN in your networking infrastructure, don’t think you’ll have to sweep aside your legacy network and build a new solution from scratch. Existing networks can be enhanced with SDN solutions that will add value to the current infrastructure. Keep in mind, SDN is a very broad concept, as it covers several different techniques and mechanisms.