In this three-part series, we examine why software-defined WAN (SD-WAN) has risen to be so popular. We also answer all the questions you wanted to ask about SD-WAN, including; what it is, what challenges it solves, the benefits and approach you should take when considering a SD-WAN deployment.

You’ve probably heard of the term “software-defined” bandied about much more often, thanks to the wide acceptance of software-defined networking (SDN) and software-defined storage.

The term is gaining attention for good reason, as the main benefit of software-defined technologies is flexibility, added speed and a better way to keep up with digital innovation.

In fact, Gartner estimates that the emerging SD-WAN (software-defined wide area network) has less than 5% market share today, but it predicts that up to 25% of businesses will manage their WAN through software within two years.

SD-WAN is related to SDN in that they’re both software-defined, but SDN is an architecture that is meant for internal data centers at a campus or headquarter location, SD-WAN is a technology you can buy.

While the technology isn’t new, and neither is centralised WAN management, combining the centralisation with the technology’s ability to dynamically share network bandwidth across connection points is making this approach popular.

WAN then… and now

Many enterprises manage WAN at their branch by deploying a complex system of routers, WAN path controllers, WAN optimisers, firewalls and other components. This is an expensive and high-maintenance approach.

SD-WAN bypasses this complexity by packaging the important features of WAN infrastructure four – path selection, low cost – and bundle it together.

Gartner estimates this approach can render SD-WAN up to two and a half times less expensive than traditional WAN infrastructure. For example, a 250-branch WAN over three years is estimated to cost US$1,285,000 in a traditional WAN architecture, but only US$452,500 with an SD-WAN deployment.

The ability to use commodity routers is the biggest savings, along with staffing and a small decrease in router maintenance and support.

There are four requirements for a system to qualify as an SD-WAN, according to Gartner. These are:

  1.    SD-WAN solutions provide a lightweight replacement for traditional WAN routers and are agnostic to WAN transport (that is, they support Multiprotocol Label Switching [MPLS], internet, 4G/LTE, etc.).
  2.    SD-WAN solutions allow traffic to be distributed across multiple WAN connections in an efficient and dynamic fashion, based on business and/or application policies.
  3.    SD-WAN solutions dramatically simplify the complexity associated with management, configuration and orchestration of WANs.
  4.    SD-WAN solutions must provide secure VPNs and have the ability to integrate additional network services.

Business applications of SD-WAN

Redmond Inc., a supplier of industrial and commercial products uses SD-WAN to provide a reliable connection for phones, point of sale (POS) and fax networking to 10 branch offices from a central office based in Utah, USA. It’s a far easier job today than it was a year ago, according to the company’s technical project manager Aaron Gabrielson.

SD-WAN helped particularly when it came to regional-based offices where traditional networking measures can be difficult and expensive. Gabrielson can now purchase cheap commercial-grade internet connections at rural branch sites and provide the sites with enough bandwidth to use voice over IP (VoIP) and process credit card transactions.

Centralised WAN management is also beneficial, notifying Gabrielson of any issues via a single interface and allowing him to easily manage and change bandwidth allocations where needed.

Organisations can also use SD-WAN for the following business applications:

  •     Aggressively moving applications to the public cloud;
  •     Moving toward a hybrid WAN topology;
  •     Reducing traditional business-class carrier service budgets;
  •     Simplifying WAN management;
  •     Reducing the cost of existing WAN remote branch equipment, often during a refresh cycle;
  •     Managing a large number of remote branches;
  •     Deploying video or other high-bandwidth, real-time applications to branch office locations; and
  •     Maintaining limited or no IT personnel on-site in remote branches.

The benefits of SD-WAN

There are three main benefits of taking a SD-WAN approach: simplified management and operation, reduced costs, and increased visibility and security.

  1. Agility via Improved Management

Gartner estimates that SD-WAN improves the time it takes for enterprises to provision network changes at branches by between 50% to 90%, due to simplifying operation, orchestration and zero-touch configuration. This, in turn, improves branch turn-up times.

  1. Cost Reduction

Enterprises can anticipate significant savings by replacing traditional WANs with SD-WAN technology. This savings comes from reduced capex from infrastructure, software and support costs at branch locations. There is also reduced opex due to reduced personnel needed to provision, manage and troubleshoot equipment. Finally, enterprises can save on NSP costs due to better utilisation of WAN connections as SD-WAN dramatically improves load sharing across multiple ports.

  1. Improved Branch Availability

SD-WAN improves overall availability of branches due to simplified failover as SD-WAN solutions dynamically assign traffic to links based on application-centric policies, versus only IP addresses and circuits. Thus, they can more easily accommodate additional links, such as multiple broadband links or cellular connections. SD-WAN also supports faster failover and congestion detection than traditional IP-based routing protocols.

The solutions also offer better visibility over branch issues, as most solution are bundled with advanced analytics and troubleshooting functionality, allowing proactive maintenance. Finally, these deployments reduce manual configurations with a high degree of automation and orchestration, leading to reduced manual configuration errors, which are a leading cause of network outages.