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Getting in the Know on SD-WAN


With application processing now taking place within the application itself, traditional lines between data, applications, processing, service providers, IT, managed services, carrier-provided services, and telecommunications continue to evolve and blur. At the same time, legacy networks are straining to keep up with cloud and SaaS applications bandwidth demand. Enterprises are addressing this challenge by adopting software-defined WAN (SD-WAN) solutions.

In addition to the other tech evolutions like cloud and 5G on the way, your business would be wise to consider SD-WAN, because if you aren't thinking about it yet, you will be soon.

There are tons of resources out there on the Web to help you get in the know about SD-WAN. And of course, your local vendors and consultants can be valuable additional assets. Rather than try to make you an overnight SD-WAN expert, I'm going to use this space to provide an overview of key developments in the SD-WAN arena.

What is Software-Defined WAN?

In short, SD-WAN is a software-based networking application technology applied to WAN transport connectivity. It can give an enterprise the ability to consolidate and virtualize WAN connectivity and functions into centralized policies designed to ease the deployment and management of complex WAN topologies.

Gartner attaches the following four characteristics to SD-WAN:

  1. Must support multiple connection types including MPLS, Internet, and LTE
  2. Can perform dynamic path selection, allowing for load sharing across connections
  3. Offers a simple UI for WAN management with zero-touch provisioning
  4. Supports VPNs and other third-party services

From an economic standpoint, the goal of an SD-WAN network is to deliver WAN connectivity at a significantly lower cost than legacy networks. As an example, consider a typical WAN network, which might be used to connect several branch offices to a data center or central corporate network. These WAN connections might use a technology that requires special or proprietary hardware, or an expensive point-to-point or MPLS network. In this case SD-WAN uses a software approach to move network control into the cloud so that less expensive internet or public cloud connections can be used instead.

Market Overview

Businesses place a high importance on the availability of reliable high bandwidth, and the ability to rapidly deploy new applications and network and data security. With the advent and proliferation of network technologies that allow increased transport capacity and reliability, so arose increased complexity, management, and cost issues. Current typical WAN architectures fail in meeting many of the needs of heavy bandwidth usage for interactive communications, video, collaboration, and deployment of cloud applications. This, combined with legacy network challenges, leaves a gap in network managers being able to provide consistent, secure, and cost-effective services.

Wide Area Networks are heavily deployed and are an important component in today's enterprise infrastructure. However, WANs have many snags such as inconsistent performance, outages, packet loss, congestion, and jitter. This further irritates users, and prevents it from being the ideal transport method for applications like VoIP, video, and virtualized applications. It can also be expensive, not to mention difficult to manage and troubleshoot.

Earlier iterations of SD-WAN solutions suffered from weak security. Today, most SD-WAN solutions use IP-SEC encryption to protect transport data. Some may add additional security such as rotating keys, splitting designated application traffic across multiple links, which can prevent a hacker from being able to eavesdrop on an entire network segment. Some products use SSL/TLS encrypted tunnels, which allows traffic shaping for traffic from Facebook, YouTube, Twitter, Google Apps, Box,, GitHub, and the many other Web applications that use SSL/TLS encryption.

SD-WAN solutions can help to mitigate many common challenges by enabling hybrid WAN solutions and providing better overall cost and operational efficiency.

The SD-WAN market represents billions of dollars in new revenues, and some research shows hundreds of millions of dollars have been invested in SD-WAN startups already. Legacy companies have their work cut out for them, with many startups having different approaches to the market. For example, Silver Peak focuses on accelerating software-as-a-service (SaaS) applications in the cloud, while Pertino and VeloCloud are focused on branch offices. Aryaka has built a global network so that companies can use WAN as a network-as-a-service (NaaS). Vendors such as Cisco and Riverbed, which make specialized appliances for WAN connectivity, are now focusing more on cloud-based WAN offerings in response to this new trend.

And the trend toward SD-WAN by enterprises is not likely to slow down. Gartner predicts that by the end of 2019, 30% of enterprises will use SD-WAN products in all their branches. Further, a Forrester Consulting study commission by Riverbed found that 90% of network managers are looking to evolve their WAN with a software-defined approach, as shown in the below graphic.



SD-WAN Business Drivers

The failure of a network link can severely negatively impact a user's business. The loss of access to a mission-critical application can reduce productivity and affect customer service. Manually trouble shooting and rerouting traffic to back-up links can mean that high-priority applications will now have to contend with other traffic for bandwidth. SD-WAN products can be an essential methodology for eliminating this type of situation and provide fast failover with little or no noticeable service interruption.

Customers are focused on cost, reliability, and security. As is now the case with many technologies, end users are moving away from proprietary products and single vendor shops, expensive fixed circuits, or specialized WAN technology that often involves expensive hardware. Enterprise customers want flexible and open, cloud-based WAN technologies.


Have we reached technology nirvana? Even with all of the benefits offered, selecting the optimal SD-WAN solution for your enterprise is not easy. As we learned with cloud, not all terminology used around SD-WAN means the same thing to everyone. Overall, SD-WAN is one of the better technologies that has come along. There is little to no downside side. Even as development continues, at this stage in its development cycle the benefits far outweigh any risks.

SD-WAN products for the most part have a very successful track record in lowering WAN costs, improving application performance, and enhancing business continuity. But there are significant differences in how vendors approach the market and implement their technology. When considering an SD-WAN deployment, it's important to understand these differences and which features will help you accomplish your goals.

Keep in mind:

  • Not all applications on the network need the same levels of service or network availability. Identify which of your applications require high performance, high reliability, and high service quality to meet customer expectations.
  • It is important that you can articulate your SD-WAN strategy. Define your success factors, understand what you want to accomplish by implementing SD-WAN -- your needs and goals are unique to your company. There are enough existing and emerging choices that you do not have to settle for a specific vendor's offerings if they don't meet your requirements.
  • Identify your goals, layout your migration path. Make sure all stakeholders are on board and understand how the transition will affect their business or operations in the short term, and what the longer-term benefits will be.
  • Do your due diligence. Just because the vendor says so, don't accept it on face value. Develop and implement a pilot with a check list of criteria that needs to be met.

"SCTC Perspectives" is written by members of the Society of Communications Technology Consultants, an international organization of independent information and communication technology professionals serving clients in all business sectors and government worldwide.