What is the Difference Between WAN and SD-WAN?

WAN, or Wide Area Network, is defined as the telecommunication network that spans across a large geographical area. WAN networks can use a variety of different leased circuit types such as MPLS, Ethernet and Internet. SD-WAN, or Software Defined Wide Are a Network, are used to better control existing leased circuit types for an enhanced more cost-effective way to connect sites together.

Normally with traditional WAN deployments, Enterprises must make costly decisions on the quality of service they require at their sites as different types of circuit types have widely different cost, and the associated SLAs (service level agreements). MPLS circuits, for example, typically have a higher uptime at a higher price point, forcing enterprises to settle for lower speed connections to keep the costs down. Similar consideration goes for EPL (Ethernet private line). On the other hand, Internet circuits offer more convenient price points at a higher speed at the expense of less stringent SLAs compared to MPLS or EPL circuits.

SD-WAN has changed the way the WAN is deployed by applying an overlay network technology to abstract the existing WAN transports, creating transport independent network fabric. SD-WAN solutions also typically offer performance remediation techniques mitigating latency, loss and jitter that can be encountered over the Internet circuits. This approach allows organizations to achieve the best of both worlds by using lower cost, high throughput Internet circuits while still retaining the higher SLAs.

How is this possible? In addition to latency, loss and jitter remediation, an SD-WAN overlay network can simultaneously leverage multiple underlying physical transports, which increases overall uptime and reliability by instantaneously shifting traffic off of the failed circuit. The use of active-active forwarding across all the transports contributes to higher bandwidth capacity for the enterprise applications.

SD-WAN provides visibility, control and quicker time to deployment (zero touch provisioning) as compared to traditional enterprise WAN. SD-WAN also plays an important role in extending enterprise WAN into the public cloud to fuel the digital transformation in the post-COVID era.