What’s the Difference Between SD-WAN and WAN?

Posted on
Nov 14, 2018
ATSI Content Team
ATSI Content Team
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Background image with system motherboard concept and question markSoftware-defined wide area networks (SD-WANs) are becoming the choice of organizations the world over. There are major advantages to choosing an SD-WAN instead of a WAN for your networks, including lowered cost, deployment speed and better use of bandwidth.

Here's a closer look at the differences between WAN and SD-WAN.

Why WAN Is Broken

WANs traditionally are built on a combination of public and leased network lines. Traditional connectivity methods rely on assigning preferences based on service level agreement (SLA) guarantees. These methods also affect the timeliness of content delivery, which can be critically important for video- and voice-based applications.

This can create complications about the reliability of network resources. Even a brief outage of a few seconds can disrupt voice and video applications. That's just one of the challenges of sticking with a WAN solution. Here are a few other issues:

  • Reliance on Data Center. With a WAN configuration, your network relies on the enterprise's data center for traffic management, often resulting in latency issues that can affect performance.
  • Bandwidth Cost. Expensive but limited private bandwidth can create application performance issues. 
  • Local Configuration. Network configuration is housed locally on each router, adding complexity and time to deployment and expansion. Appliances and devices are frequently single-function and connect via different WAN links, further complicating branch WAN management. 

The Differences with SD-WAN

SD-WAN acts as an overlay on your existing network; think of it as a single pane of glass to manage the complete networking solution, including the setting and usage of policy. The policy controls traffic paths, failovers, monitoring and SLAs that are written based on application-specific settings. 

Once the SD-WAN is configured and the policies are in place, it's a hands-off technology. The network monitors performance and moves traffic based on the programmed SLAs. 

As the name implies, SD-WANs are software-driven, powered by application awareness that's managed centrally on the network. They allow for easy configuration and deployment across all locations.

With an SD-WAN deployment, companies gain considerable advantages in speed and agility of provisioning, as well as cost and ease of network creation and configuration. Using cloud-based virtualization tools, SD-WANs use the Internet to improve performance and speed of your applications.

Some other advantages of the SD-WAN solution are:

  • Lower Circuit Costs. Using broadband and DSL solutions, SD-WAN eliminates the need for costly private or shared circuits. 
  • Cloud-Based Services. With an SD-WAN, there will be less latency and poor routing with cloud-based applications like Microsoft Office 365.
  • Simplified Branch Management. You can insert network services into a new location using SD-WAN automation and policy features, drastically simplifying the configuration of traffic routing and policy alignment in new locations.
  • Scalability. SD-WAN can be used to create a wide area network either on-premises or in the cloud. Using cloud-based management of your applications allows for rapid scaling via pay-as-you-grow subscription pricing models.


At ATSI Business Communication Systems, we help customers with solution-driven services. We deliver thorough assessment, design and deployment solutions that help businesses communicate better. To learn more about our network optimization services, contact us today.