MPLS vs SD-WAN: Which Is Best for Multi-Site Businesses?

If you run several sites and your applications now live in Microsoft 365, Azure or other cloud platforms, the wide-area network you bought a decade ago is probably costing you more than it should. This is the practitioner's comparison of MPLS and SD-WAN — what each actually does, where the money goes, and which one we recommend. For the underlying circuits behind either approach, start with our business leased lines pillar.

What is the difference between MPLS and SD-WAN?

MPLS is a private carrier network that moves traffic between your sites over dedicated, contended-free circuits the provider controls. SD-WAN is a software layer that sits on top of any internet connections you already have — broadband, FTTP, leased lines or 4G/5G — and intelligently steers traffic across them.

The distinction matters because it changes who controls the network and what it costs. With MPLS, the carrier owns the routing and the quality guarantees, and you pay a premium per site for that. With SD-WAN, you own the policy: your team (or AMVIA) decides which application takes which path, and you buy the underlying bandwidth on the open market. SD-WAN is transport-agnostic, so a single site can blend a dedicated internet access circuit with a cheaper broadband backup under one managed policy.

MPLS vs SD-WAN: side-by-side comparison

The two approaches solve the same problem — reliable connectivity across multiple locations — in very different ways. This table is the at-a-glance view; the sections below explain the trade-offs.

How much cheaper is SD-WAN than MPLS?

SD-WAN is usually the cheaper option because it runs over commodity internet circuits rather than premium private MPLS bandwidth. The source figure most often quoted is that "SD-WAN typically reduces WAN costs by approximately 50% compared to MPLS" — the exact saving depends on your circuit mix and site count.

A worked example makes it concrete. A five-site business paying around £2,000 per month for MPLS can often achieve equivalent or better performance on SD-WAN for roughly half that, while gaining faster deployment and central control. AMVIA designs and manages SD-WAN deployments for multi-site SMEs from as little as £150 per site per month. A 100 Mbps leased line underlay is available from £69 per month — useful where you want guaranteed bandwidth under the SD-WAN layer. For a full breakdown of circuit pricing, see our leased line cost guide.

When does MPLS still make sense?

MPLS still earns its keep where the network must stay private end to end. It was designed to route traffic between private data centres, so organisations with strict data sovereignty rules, regulated workloads that cannot touch the public internet, or legacy applications built for private transport may still prefer it.

That profile is shrinking. As more workloads move to Microsoft 365 and Azure, backhauling cloud traffic across a private core to a central breakout point adds latency and cost for no benefit. If most of your applications are SaaS, MPLS is solving a problem you no longer have. The honest rule of thumb: choose MPLS only when a specific compliance or legacy constraint forces private transport — not as a default.

When should you choose SD-WAN?

Choose SD-WAN when your applications live in the cloud, you have multiple sites to connect, and you want to control cost and routing yourself. It gives each location direct local breakout to the internet, prioritises voice and video automatically, and fails over between circuits without manual intervention.

It is the stronger fit for the businesses we work with most:

• Fast-growing or multi-site SMEs that need to add or move locations quickly — a new site can come online in days, not months. See multi-site connectivity.
• Cloud-first organisations running Microsoft 365, Azure or hosted line-of-business apps.
• Teams that want resilience by combining two diverse circuits with automatic backup connectivity.
• Cost-conscious finance leaders who want predictable per-site pricing on commodity bandwidth.

Can SD-WAN match MPLS reliability for voice and video?

For most use cases, yes. SD-WAN uses application-aware routing to identify voice and video and place it on the best-performing path in real time, bonding multiple internet connections for redundancy. The result is comparable call and video quality to MPLS without the private-circuit premium.

UK internet quality supports this: average fixed broadband download speeds sit around 69.4 Mbps (Ofcom Connected Nations 2024), and most business districts now have full-fibre options. Where calls and conferencing are genuinely mission-critical, pair SD-WAN with a leased line underlay to deliver MPLS-grade performance on the path that matters. Outages are not hypothetical — UK businesses lost around £3.7bn to internet downtime in 2023 (Beaming research), which is exactly why diverse-circuit failover is worth designing in.

How does the choice affect your network security?

Security is where the WAN decision quietly matters most. MPLS keeps traffic on a private core but offers little inspection at the edge; SD-WAN gives each site direct internet breakout, which improves performance but widens the attack surface unless every branch is properly protected.

This is the security-first part of the brief. Direct breakout at twenty sites means twenty places an attacker can probe, so an SD-WAN rollout should ship with edge firewalling, segmentation and monitoring as standard — not as an afterthought. The UK's National Cyber Security Centre sets out sound design principles for exactly this kind of distributed network in its secure network design guidance. We build connectivity and protection together — see how we combine leased line security with managed monitoring so your network is fast and defended.

What AMVIA recommends for UK multi-site businesses

For UK businesses with multiple sites moving to cloud-first working, SD-WAN offers better value than MPLS. It delivers traffic prioritisation, failover and central management across every location — without the long lead times and rigid pricing of MPLS circuits. We design, deploy and manage the whole stack: the underlying circuits, the SD-WAN policy, and the security around it.

That is the AMVIA difference in one line: one provider, security-first, Microsoft-certified. You get a single accountable team for connectivity and protection, rather than a telecoms reseller who stops at the router.