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SD-WAN vs. SDN: Demystifying the Differences

SD-WAN vs. SDN: Demystifying the Differences

Over the past 12 months the buzz around SD-WAN has exploded. It’s becoming to networking what the cloud became to infrastructure and applications. Yet, while the concept of a Software Defined WAN is generally understood, it’s often confused with its technology cousin, Software Defined Networking (SDN). Even by people who seem to be in-the-know.

So I thought it was about time someone explained the difference.

SDN and SD-WAN have more in common than “SD”

SD-WAN and SDN share a common heritage in that both are enabled by (excuse the technical jargon) the separation of the Control Plane and the Data Plane. Additionally, they’re both designed to run on commodity based x86 hardware, can both be virtualized, and can both support the integration of additional Virtual Network Functions (VNFs) such as security, or WAN acceleration.

SDN was designed to support the needs of modern computing environments inside Local Area Networks (LANs) and within a Service Provider’s networks. The goal was to create dynamic, flexible, and scalable connectivity to support changing demands in the data center and on core networks. SDNs are directly programmable, providing an agile and centrally managed network platform that decouples the Control Plane (which decides where traffic is routed) – from the Data Plane (which determines how traffic is forwarded).

These are the same underlying principles that power SD-WAN. However, it is important to note that SD-WAN and SDN are not the same thing.

SD-WAN vs. SDN: The Differences Are In the Details

Like many cousins, SD-WAN and SDN closely resemble each other, but they are very different people (so to speak). The main thing being SD-WAN’s focus is providing software defined application routing capabilities for Wide Area Networks, connecting a single organization’s geographically distributed locations (HQ, data centers, branches, remote users), on a regional, national or global basis. Whereas SDN is primarily focused within the LAN (locally) or within the Service Provider’s core network.

That might seem like a lot to take in, so, to quickly summarize:

  • SDN is a solution that is completely programmable by the end-user/customer, allowing for efficient change and configuration management. While SD-WAN is built on SDN technology, the programming is handled behind the scenes by the SD-WAN vendor, eliminating the end-user complexity.
  • SDN is focused within the network, be it the LAN or Service Provider’s core. While SD-WAN is focused on the connectivity between networks over the WAN.
  • SDN is enabled by Network Function Virtualization (NFV), which provides multiple virtualized network functions via software previously built into proprietary, closed systems. In contrast, SD-WAN provides software defined application routing that can be virtualized and run on either an SD-WAN appliance or virtually.

SD-WAN: From Packets to Applications, and More

SD-WAN technology changes the network paradigm from a packet-based routing system to an application-based routing system, allowing organizations to use consumer grade Internet with improved quality and performance, with a lower cost per megabyte than MPLS.

That’s not all; SD-WAN provides tremendous network agility and flexibility, while maintaining centralized business policies that control how applications are routed. With the resulting visibility and control, you can identify the applications that are running across your WAN and set policies on the prioritization and usage of those apps.

SD-WAN also uses dynamic WAN selection technology to route prioritized apps over the best performing paths. In addition, it can utilize multiple available links in an active / active configuration to provide for load balancing and immediate failover, with minimal-to-no perceived interruption. The traffic between sites flows over dynamically built tunnels that are fully encrypted, providing a high level of security.

Summary: All “SD” Technologies Were Not Created Equal

All this may sound pretty technical, but in reality, SD-WAN removes the complexity from the end user, providing an easy to use and understand set of network tools and analytics for those running the network.

While some companies may decide to implement SD-WAN on their own, there are benefits to leveraging an experienced service provider. Especially if you need to integrate SD-WAN into an existing network. To do that, you’ll need to understand how your network and value added services (such as voice, video, and WiFi) are configured, and understand the impact to your security model. These are the sorts of things a provider can be very good at.

Now that we’ve demystified SD-WAN a bit, you’re readier than ever to speak with your provider about putting the advantages of SD-WAN to work for your organization.


The Path to SD-WAN Starts with Hybrid Designs

HybridVidWhile SD-WAN will bring major change to the enterprise, the path to getting there is more evolutionary than revolutionary. For most organizations, the best place to start can be with Hybrid Networks combining the predictable performance of MPLS, the cost efficiency of IPsec VPNs, and the visibility and control of software defined technologies for application performance optimization.

Watch Video: Hybrid Networking

About Michael J. Miller

Michael J. Miller
Michael Miller is passionate about technology. He works in the Office of the CTO at EarthLink, responsible for researching and evaluating new technology trends that will shape the future of business and communications. He has 20+ years of experience in IT, security, and operations. Prior to EarthLink, Michael was CMO at Renesys Corp., an Internet Intelligence company, responsible for strategy and new product development. He’s also held multiple executive level positions at Global Crossing, including eight years as Head of Global Security (responsible for protecting their global network, systems, assets, and resources). He also led their IT Operations team, developing their infrastructure strategy, consolidating operations, driving operational efficiency, and improving operating costs. Michael is a Certified Information Systems Security Professional (CISSP), he has Master's certificate in Project Management from George Washington University, and a Bachelors' in Accounting from St. John Fisher College.