SD-WAN vs. MPLS: The quality-of-service comparison


SD-WAN vs. MPLS: The quality-of-service comparison

2018.02.23 15:34:49 Source:

SD-WAN vs. MPLS is how quality of service differs between the two.

Layer 3 MPLS VPNs provide end-to-end privacy, with service-level agreements (SLAs) that specify bandwidth,quality of service (QoS), latency and uptime. Although prices for MPLS WAN services have decreased, the pricing correlates to the higher demands of corporate businesses.

The internet vs. private infrastructure

The typical enterprise must balance cost-effectiveness with the need to meet specific business objectives. Companies are consuming more cloud-based services across the internet, as the workplace is no longer tethered to the office. In many respects, an MPLS VPN underserves users working outside corporate headquarters, because the typical remote access connection is often supported by an IPsec VPN client with limited functionality.

Let's identify the potential downsides of SD-WAN over the internet:

The internet is a collection of networks; therefore, application performance cannot be guaranteed on an end-to-end basis.

The internet doesn't recognize QoS markings and sees all traffic as the same, regardless of type.

SD-WAN providers typically fall into three camps. The first includes service providers that are often agnostic where connectivity is concerned. To keep costs down, these providers may source low-cost internet connectivity from various providers across the globe.

The second set of service providers is the same as the first, but their strategy is to use a single public IP backbone where possible.

The third category includes the traditional telecom providers -- think AT&T, Verizon and BT -- that use their own single public IP backbone.


Business application data that travels over numerous public IP backbones -- i.e., the internet -- will often suffer from unpredictable  performance. While many applications will operate well, delay-sensitive traffic may suffer and become unusable.

In comparison, the use of a single internet backbone is a more predictable for corporate traffic. In many cases, premium internet connectivity is backed by latency and uptime guarantees.

The choice of multiple paths

To mitigate against potential internet performance issues, SD-WAN offers some clever functionality.

While MPLS offers end-to-end QoS across a single path, SD-WAN's trump card is the technology monitors the state of current network connections for performance issues. This same benefit may be the biggest differentiator of SD-WAN vs. MPLS. Depending on budget, companies can use multiple connectivity types that will fail over based on state. If the primary connection becomes degraded, the typical MPLS service won't offer an alternative path unless a complete outage occurs.

WAN vs. MPLS: The QoS comparison

Ultimately, MPLS is a predictable technology for sending mission-critical or delay-sensitive traffic end to end across the network, with strict QoS against the SLA.