What is SD-WAN?


Everything you want to know about SD-WAN but are afraid to ask. 


First, let’s cover WAN basics

The job of the Wide Area Network (WAN) is to connect users to their applications at any time from anywhere on any device, and to wherever those applications reside. 

Over the past two decades, the way we built WANs were centered around having branch offices connected to a headquarters-based data center. This was executed by a router over a lease-line connection, like MPLS. 


A change in WAN requirements

Today, traffic patterns have changed with the introduction of applications moving to the cloud. These applications include enterprise apps like:

  • AWS
  • Microsoft Azure
  • Google Cloud
  • Oracle Cloud Marketplace


Or SaaS applications like:

  • Salesforce
  • Workday
  • Microsoft 365
  • Dropbox
  • YouTube 


Because of this change, sending cloud traffic that is destined for the Internet back to headquarters simply doesn’t make sense - it adds delay, degrades application performance, and consumes costly leased-line bandwidth. 


To match today’s WAN requirements for a software-driven model, enterprises are moving towards a software-defined WAN or SD-WAN. 


Instead of routing traffic solely based on addresses, an SD-WAN is application-aware. It uses software to more intelligently route traffic across the WAN - based on the priority, performance, and security policies required by that application. 


An SD-WAN that has the right set of features also enables the ability to actively use the Internet as a secure and reliable form of WAN transport. The SD-WAN decouples the WAN transport services (aka the Data Forwarding Plane) from the applications and from the control function. 


This is a very different model used than the traditional router because these features are all combined in every device. SD-WAN also features a control function called the Control Plane is centralized. The quality of service and security policies that dictate how an application should be delivered to the user are defined centrally and programmed automatically to hundreds or even thousands of SD-WAN appliances at branch locations. This leads to more consistent and predictable application performance and more consistent and improved security across the WAN


Additionally, by using a software-defined WAN, adding locations, adding applications, or changing policies is so much easier than with the old router-centric model. 



An SD-WAN is a more intelligent, cloud-first way to build a WAN. An SD-WAN:

  • Improves business productivity
  • Provides a higher quality of experience
  • Accelerates initiatives
  • Has the potential to lower costs


How do I know if SD-WAN is right for my business?

Do you struggle to determine how to: 


  • Use the Internet to connect users directly to cloud applications for the best performance
  • Continuously deliver a high-quality experience for every business-critical app
  • Keep up with changes to their WAN without configuring and administering device-by-device
  • Deliver new applications to 100s or 1000s of sites, across multiple clouds, 10 percent of the time
  • Continuously monitor all applications and WAN services to know which issues to focus on across 1000s of sites
  • Reduce human errors in a complex and ever-changing environment
  • Deliver significantly more bandwidth at the WAN edge, for the same budget
  • Ensure their WAN is never a roadblock and always keeps pace with the business
  • Protect their business when the cloud is open, accessible and everything is connected


If you are running applications in the cloud and can relate to any of the above challenges, we recommend making the shift to SD-WAN. 


Getting started with SD-WAN

Now that we’ve defined SD-WAN and covered some business challenges you may be facing, how does one get started implementing SD-WAN?


In the past few years, the industry has seen more than 60 companies market SD-WAN as part of their offerings. Most include basic SD-WAN features such as the ability to use multiple forms of transport, dynamic path selection, centralized management, zero-touch provisioning, and encrypted connections. When shopping for the right solution, we recommend looking for the following features: 


Lifecycle orchestration and automation

Most basic SD-WAN offerings provide some level of zero-touch provisioning. We recommend looking out for solutions that provide full end-to-end orchestration of all WAN edge functions such as routing, security services including service chaining to advanced third-party services, and WAN optimization. 


Example: If you deploy a new application or when a QoS or security policy change is required, your SD-WAN should centrally configure and implement the required changes in a few hours vs. weeks or months. 


Continuous self-learning

Basic SD-WAN solutions will steer traffic according to pre-defined rules, usually programmed via templates. We recommend features that will continuously monitor and self-learn the state of the network to deliver optimal application performance - even when network changes, congestion, or impairments occur. 


Example: If one of your third-party cloud security services goes down, self-learning SD-WANs will not only detect a resource deterioration or the outage, but they automatically remediate to keep traffic flowing when maintaining continuous compliance with business policy. 


Consistent quality of experience

A key benefit of an SD-WAN solution is the flexibility to actively use multiple forms of WAN transport. A basic solution can direct traffic on an application basis down a single path, and if that path fails, or is underperforming, it can dynamically redirect to a better-performing link. However, with many basic solutions, failover times around outages measures in the tens of seconds or longer, often resulting in perceptible — and annoying — application interruption. 


Your SD-WAN should have the ability to intelligently monitor and manage transport services - like overcoming problems of packet loss, latency, and jitter. It should deliver the highest levels of application performance and quality of experience to users, even when WAN transport services are impaired. 


End-to-end segmentation

Lookout for a platform that enforces end-to-end segmentation spanning the LAN-WAN-Data Center. This will eliminate configuring policies device-by-device. 


Example: If a policy requires a change, your SD-WAN should allow you to program it once and push it out 100s or even 1000s of nodes across your network. This will help you see a significant increase in operational efficiency. 


Direct internet breakout to cloud applications

Because cloud applications are continuously changing, your SD-WAN should be able to keep pace by continually adapting to those changes. Looking out for this feature will help you avoid application breaks to keep user productivity consistent. 


VLCM recommends

For a business-driven SD-WAN with the highest quality of experience, VLCM recommends the Aruba EdgeConnect Enterprise SD-WAN unified platform. EdgeConnect is designed to enable enterprises to fully realize the transformational promise of the cloud and achieve consistent application performance even through transport interruptions and brownouts. Aruba enables enterprises to build a modern WAN that drives maximum value from cloud and digital transformation initiatives with a self-driving network that learns and adapts to the needs of the business. 


Stay tuned for our next blog in our SD-WAN series to learn how Aruba EdgeConnect SD-WAN enables enterprises to achieve the highest return from their cloud investments, or get in touch with one of our many Networking Engineers to get started on your SD-WAN transformation.