History and characteristics of SD-WAN

The term Software-defined Wide Area Network (SD-WAN) refers to a wide area network that uses software-defined network technology, such as overlay tunnels for internet communication that are encrypted while going to locations inside an organization. 

By separating the networking hardware from its control mechanism, SD-WAN makes it easier to manage and operate a WAN, provided that the standard tunnel setup and configuration messages are supported by all of the network hardware vendors. This idea is comparable to how software-defined networking uses virtualization technologies to enhance the management and operation of data centers. 

In reality, setting up and managing an SD-WAN solution requires the usage of proprietary protocols, therefore, the hardware and its management system are not separated.

Talking about the uses of SD-WAN, one of the main use for SD-WAN solutions is to enable enterprises to create higher-performance WANs, which helps them by utilizing less expensive, commercially available internet access, allowing them to partially or completely replace more expensive private WAN connection technologies like MPLS.

However, there are no end-to-end performance assurances when SD-WAN traffic is transmitted over the internet. Carrier MPLS VPN WAN services are provided with an end-to-end performance guarantee and are not sent over the internet but instead, are sent over carefully monitored carrier capacity.

But what does SD-WAN do? 

Let us first understand the basic functionality of a WAN to discuss what SD-WAN does. WAN gives businesses the ability to expand their computer networks over considerable distances, linking distant branch offices to data centers and to one another while offering the applications and services necessary to carry out business operations. 

However, WANs face significant operational challenges, such as network congestion, packet delay variation, packet loss, and even service outages. These challenges are caused by the physical limitations imposed by the propagation time over great distances and the requirement to integrate multiple service providers to cover global geographies (often crossing national boundaries). 

Another drawback WAN experiences is that it provides latency and is cost-consuming for scaling the network. Low latency is necessary for contemporary applications, including VoIP calling, video conferencing, streaming media, and virtualized apps and desktops. The need for bandwidth is also growing, particularly for applications that use high-definition video. But expanding WAN capability can be expensive and challenging, and managing and troubleshooting networks can be challenging as well.

These network issues are the main focus issues that SD-WAN products solve. Cost effective consumer-grade internet links can behave more like a dedicated circuit by upgrading or even replacing typical branch routers with virtualization appliances that can regulate application-level policies and provide a network overlay. For a branch staff using SD-WAN, this makes the setup procedure simpler.

History of SD-WANs

SD-WAN played a significant role in the advancement of networking technology in general and was, for a considerable amount of time, one of the most significant uses of networks for both business and military purposes.

Let us understand the history of WAN and how it evolved into more reliable and secure SD-WAN:

One of the key forces behind the development of data communications technologies was the capacity to transmit data across long distances, which lowered the time required to exchange messages with other parties and allowed for the elimination of distance restrictions.

Communication over circuits linking two or more endpoints was made possible by WAN technologies. In the past, point-to-point communication over a slow circuit, typically between two fixed places, was supported. 

WAN circuits got faster and more flexible as technology advanced. Today, communication may become more dynamic and accommodate ever-expanding networks thanks to innovations like circuit and packet switching (in the form of X.25, ATM, and subsequently Internet Protocol or Multiprotocol Label Switching communications).

However, multinational organizations were extremely cautious while leasing and managing their WANs due to the necessity for stringent control, security, and quality of service.  The businesses that could offer local services in each nation were constrained by national rules, and intricate agreements were required to build genuinely global networks. 

All of that changed when the internet expanded and made it possible for organizations all over the world to connect with one another. In the early years, though, the internet’s lack of regulation was not regarded as suitable or secure for use by private corporations.

Independent of worries about safety, having a connection to the internet became essential to the point where each branch needed it. Private conversations were initially still carried out over WAN owing to safety concerns, while communication with other entities (including clients and partners) was transferred to the internet.

The NAP or Network Access Point was also a considerable factor. NAP acts as the intersection for ISPs or Internet Service Providers to exchange packets. Network Access Points are the source where these service providers interconnect their lines so as to bring about the internet as a single entity. With high-speed switching facilities, a NAP or Network Access Point can transfer traffic from multiple lines to and fro easily.

Thus, businesses began to consider ways to use the internet for confidential corporate communications as it expanded in scope and matured over time. Early in the new millennium, application delivery via wide-area networks (WAN) emerged as a significant area for academic study and industrial innovation. 

Over the following decade, as computing power improved, software-based appliances that could analyze traffic and make defensible decisions in real-time could be developed. These appliances allowed for the development of massive overlay networks over the public internet that could perform all the functions of legacy WANs at a fraction of the price.

Introduction of Software Defined overlay to existing WANs

To build complete private networks with the ability to dynamically share network bandwidth among the connection points, SD-WAN solutions incorporated a number of technologies. 

Centralized policy administration and security were made possible by other improvements like central controllers, zero-touch provisioning, integrated analytics, and on-demand circuit provisioning. Some network intelligence was also hosted in the cloud.

As of 2014, networking journals began referring to this new networking craze as SD-WAN. With the quick transition to remote work brought on by lockdowns and stay-at-home directives during the COVID-19 pandemic, SD-WAN gained ground as a method of tying remote employees together. 

Characteristics of SD-WAN 

Having discussed the history, let’s see what the characteristics of SD-WAN are.

  • SD-WANs have the capacity to handle a variety of connection types, such as MPLS, last mile fiber optic network, or via high-speed cellular networks, such as 4G LTE and 5G wireless technologies.
  • SD-WAN boasts of a capability to dynamically choose a path for load balancing and resilience purposes. 
  • Lastly, SD-WAN solutions have a user-friendly interface that is straightforward to set up and maintain support for VPNs, as well as the ability to use third-party services like web gateways, firewalls, and WAN optimizer controllers. 


SD-WAN solutions, highly efficient and fast Wi-Fi, Network Access Points, etc. are concepts that are of much importance today. Improving one’s business performance is highly dependent on these network solutions. Thus, such important aspects must be implemented and integrated within the organization to ensure smooth operations. 

Adil Husnain

Adil Husnain is a well-known name in the blogging and SEO industry. He is known for his extensive knowledge and expertise in the field, and has helped numerous businesses and individuals to improve their online visibility and traffic. He writes on business, technology, finance, marketing, and cryptocurrency related trends. He is passionate about sharing his knowledge and helping others to grow their online businesses.