MPLS is a private network run by a service provider that carries your sites' traffic on its own backbone. SD-WAN is a software layer that steers traffic across any mix of links, including MPLS, broadband and cellular. They are not strict rivals: many companies run SD-WAN on top of an MPLS circuit.
What does MPLS give you?
MPLS-based VPNs, described in RFC 4364, let a provider use one IP backbone to serve many customers. The customer's edge routers hand routes to the provider's edge routers, and packets are tunneled through the core so that core routers do not need to know the customer routes. The result is that sites reach each other over a network that is separate from the public internet.
One line in that RFC matters for security. The method does not by itself encrypt the data or detect tampering in transit. Isolation is a property of the provider's configuration, and if you want confidentiality you must add cryptography. Many buyers assume "private" means "encrypted". It does not.
What does SD-WAN change?
NIST SP 800-215 explains that SD-WAN separates the control plane from the data plane and lets you set policy centrally: access control, routing and application priority. Its listed features include connectivity over any transport (MPLS, broadband, 4G, 5G), application awareness that picks the best path per application, integrated security functions, and central visibility.
The same guide names two limits of MPLS as an enterprise WAN. First, traffic to the internet often has to travel through designated access points, a hairpin that adds latency for time-sensitive applications. Second, MPLS uses different appliances and configuration procedures, which makes management complex. It also mentions cost.
How do they compare side by side?
| Question | MPLS | SD-WAN |
|---|---|---|
| Who runs the path? | The provider's backbone | You choose, over any links |
| Cloud and internet access | Through limited access points | Local breakout possible |
| Encryption | Not built in | Typically built into overlay tunnels, verify yours |
| Where policy lives | Provider and edge routers | Central controller |
| Main new risk | Provider misconfiguration | Controller compromise, weak branch exits |
Which one fits which situation?
A constructed example: a regional bank with 60 branches and one data center. Most apps are inside the data center, and the regulator expects predictable performance for a core banking system. The bank keeps MPLS for core traffic and adds SD-WAN with broadband for guest Wi-Fi, cloud office tools and backup. Latency-sensitive traffic keeps a stable path, while cloud traffic leaves locally and gets inspected.
A different company, an online retailer with 12 small offices and almost everything in SaaS, has little reason to pay for private circuits. Broadband links under SD-WAN with cloud-delivered security may fit.
Neither choice is safe on its own. SP 800-215 describes SD-WAN as a networking feature set and treats security as an architecture you must add, in point products or in a combined cloud service such as SASE.
How to check or apply this
- Map your applications: which live in a data center, which in SaaS, which in IaaS? The split drives the WAN design more than any product brochure.
- Measure real latency from three branches to your top five applications on today's WAN.
- Ask your MPLS provider in writing what isolation guarantees and logging you get, and whether traffic is encrypted.
- If you plan SD-WAN, decide where internet traffic is inspected: at the branch, in a cloud service, or backhauled.
- Protect the SD-WAN controller with multi-factor authentication and restricted admin access.
- Pilot at two sites, run old and new paths in parallel for a month, then compare cost, outages and support tickets.
Quick check
Is MPLS more secure than SD-WAN?
Not by default. MPLS offers separation by the provider's design but no encryption on its own. SD-WAN usually encrypts overlay tunnels but adds a controller to protect. Compare the actual configurations.
Can I use both together?
Yes. NIST SP 800-215 lists MPLS among the transports an SD-WAN can use.
Sources
- RFC 4364, BGP/MPLS IP Virtual Private Networks
- NIST SP 800-215, Guide to a Secure Enterprise Network (secure enterprise networks guide)
Last reviewed: 18 October 2026.
