What Is SD-WAN and Why Is It So Important?

This is part one of our posts on SD-WAN technology. In the second post, SD-WAN and Branch Networks: Made for Each Other, we examine why this technology is becoming real game changer for branch networks.

What is SD-WAN?

These days, there’s a lot of buzz about SD-WAN and for good reason. The SD-WAN market is exploding alongside the growth of edge computing and digital transformation. Gartner estimates that by the end of 2023, more than 90% of WAN edge infrastructure refreshes will be SD-WAN (or other virtualized platforms) versus traditional routers.1 But there is also a lot of confusion about what SD-WAN is and why it’s so important.

SD-WAN stands for Software-Defined Wide Area Network. Obviously, it’s a combination of a software-defined network (SDN) and a wide-area network (WAN). To better understand what it is, let’s break it down by its parts.

SDN is a cloud-computing approach used for internal data centers at a headquarters. It was designed to enable network administrators to respond quickly to changing business requirements via a centralized interface.

A WAN is used to connect enterprises over large geographic areas. It is the network outside your headquarters which connects your data center to remote locations. It traditionally consists of site-to-site Multi-Protocol Label Switching (MPLS) hub-and-spoke architectures connecting branches to headquarters.

So, in essence, SD-WAN gives you the best of both worlds. You’ll get the ability to manage your entire WAN centrally via the cloud even if your enterprise is dispersed with hundreds or thousands of locations across the country.

In explaining SD-WAN, Gartner analyst Andrew Lerner said, “SDN is an architecture, whereas SD-WAN is a technology you can buy.”2

SD-WAN uses the cloud and the internet to connect the headquarters’ data center and branch locations. As opposed to router-centric MPLS WANs, SD-WAN networks separate the network management, traffic, and monitoring functions from the hardware. And, unlike MPLS networks that lock you into a contract with one provider, SD-WAN networks offer the flexibility of being able to support multiple carrier options.


According to Gartner, SD-WAN has four characteristics.3

  1. It must be agnostic and support multiple connection types such as MPLS, 4G, LTE, the internet, etc.
  2. It can support load sharing and dynamic path sharing of traffic across multiple connections.
  3. It must be easy to manage and easy to change with zero-touch provisioning. The level of expertise required for configuration should be akin to setting up a home Wi-Fi network.
  4. It must support secure VPNs and third-party services, such as WAN optimization controllers, firewalls, web gateways, etc.

Ok, there are the basics on what SD-WAN is. Let’s take a look at how and why is SD-WAN being used and what benefits can you gain from it.

SD-WAN Drivers

The market for SD-WAN is undergoing rapid and dramatic changes fueled by the need for digital transformation. Today’s sophisticated users expect technology to enable real-time business decisions, facilitate workflows, boost productivity, and provide better user experiences with consistency and at scale across the enterprise.

“Digital transformation is quickly becoming the largest driver of new technology investments and projects among businesses,” said Craig Simpson, IDC research manager. “It is already clear from our research that the businesses which have invested heavily in digital transformation over the last two–three years are already reaping the rewards in terms of faster revenue growth and stronger net profits compared to businesses lagging in digital transformation initiatives and investments.”4

Digital transformation is placing more pressure on networks in terms of greater demands for bandwidth and data transport. But there is a major gap between what current infrastructures support and what organizations want to do. Legacy IT architectures and deployment models are simply not up to the task. Complexity challenges are overwhelming networks and IT staff resources. Yet the demands for digital transformation just keep escalating.

According to IDC, by 2020, at least 55% of organizations will be digitally determined, transforming markets, and reimagining the future through new business models and digitally enabled products and services.5

Here are five major factors related to digital transformation that are contributing to the adoption of SD-WAN.6

  • Refresh of existing, legacy branch networking equipment
  • Change/renewal of managed services contracts
  • Changing data traffic patterns due to the cloud making hub-and-spoke WAN architectures obsolete
  • Physical expansion of facilities/locations
  • Desire to increase agility and automation

Why is SD-WAN so Important

The many benefits of SD-WAN is making it an appealing alternative to MPLS networks for CIOs, CFOs, and line-of-business managers.

First and foremost, SD-WANs offers IT professionals simplicity and the ability to manage an entire WAN through a single, centralized interface. With zero-touch provisioning, making enterprise-wide network upgrades can be done in minutes instead of weeks or months. It also eliminates the need for on-site technicians to do expensive and time-consuming configurations at every location.

End-to-End Visibility. Achieve better network visibility, control, and analytics through a single management interface. Legacy networks are incapable of providing insight into network and application behaviors. SD-WAN gives IT managers a clear view across the entire enterprise network from the local branch to the cloud to the headquarters.

Reduced Costs. SD-WAN is inherently less expensive than traditional hub-and-spoke networks because you eliminate the need for costly routers and other traditional network equipment at each location. You also eliminate the need to dispatch techs to install and maintain the network locally. In addition, some enterprises may not be able to justify the high cost of an MPLS circuit at small, remote sites, if it is even available in rural areas. It’s been estimated that SD-WAN costs (hardware, software, support) can be up to two and a half times less than traditional WAN architectures.7

Increased Performance. SD-WAN improves both application and network performance. Because SD-WAN dynamically allocates bandwidth, data travels across multiple connection paths simultaneously using the fastest routes. You also have the ability to control bandwidth at each location depending on mission-critical and non-critical applications.

Increased Uptime. With a centralized management interface, you’ll reduce troubleshooting time and increase uptime. By aggregating multiple ISP and WAN connections, you get seamless redundancy in case one path fails. MPLS networks do not always have a failover to a secondary connection.

Improved Reliability. SD-WAN is optimized for access to the cloud and for remote access to on-site resources. It also improves the efficiency and reliability of cloud applications such as SalesForce and Microsoft Office 365.

Increased Flexibility. SD-WAN frees you from being locked into contracts with one provider. With SD-WAN, you can switch carriers, mix and match carriers, and create hybrid SD-WAN/MPLS networks.

The move to SD-WAN is fundamentally changing the way enterprises communicate. The basic infrastructure of enterprise networks is evolving from a proprietary, vendor-specific MPLS network to a vendor-agnostic cloud transport network that is easily deployed, centrally managed, and less expensive.

Black Box offers state-of-the-art SD-WAN technology in its SimplEdge “network-in-a-box” bundle, which includes everything needed for branch networks from the cabling. Wi-Fi and security to complete professional, managed services. Learn more about SimplEdge at blackbox.com/simpledge.

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  1. Gartner Magic Quadrant for WAN Edge Infrastructure; Joe Skorupa, Andrew Lerner, Christian Canales, Mike Toussaint; October 2018
  2. Network World; SD-WAN: What is it and why you’ll use it one day; June 12, 2017
  3. Gartner Blog Network; Andrew Lerner; July 7, 2015
  4. IDC Media Center; Businesses Will Spend Nearly $1.2 Trillion on Digital Transformation This Year as They Seek an Edge in the Digital Economy, According to a New IDC Spending Guide; April 24, 2019
  5. IDC FutureScape: Worldwide Digital Transformation 2019 Predictions; Nov 7, 2018
  6. Gartner Magic Quadrant for WAN Edge Infrastructure; Joe Skorupa, Andrew Lerner, Christian Canales, Mike Toussaint; Oct 2018
  7. Network World; SD-WAN: What is it and why you’ll use it one day; June 12, 2017
NetworkingInnovation TechnologyImportance BusinessConnectivity DigitalNetworks WANTransformation ConnectivitySolutions SDWANTrends SDWAN EnterpriseNetworking NetworkTechnology Branch Networks Dispersed Enteprise Networks Enterprise Networking GSI Managed Services MPLS SD-Wan Wide Area Networks
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