SD-WAN vs. MPLS: Which Is Right for You?

SD-WAN vs. MPLS: Which Is Right for You?

The corporate WAN plays an important role in connecting distributed branch locations, which have become more distributed with the growth of cloud computing and remote work. At the same time, the increased reliance on SaaS and other IT applications makes WAN performance and reliability essential to an organization’s success. 

MPLS and SD-WAN take very different approaches to implementing a corporate WAN, and this blog dives into the differences between them and how to decide which is a better fit for your business needs. 


Understanding SD-WAN vs MPLS 

SD-WAN and MPLS are two methods for implementing a corporate WAN, routing traffic between distributed branch locations while ensuring a certain level of performance, reliability, and security. That said, the two have significant differences in how they accomplish these goals. 

SD-WAN Overview 

SD-WAN is a logical overlay network that connects corporate locations. SD-WAN ensures WAN’s reliability and performance by monitoring network links’ health and selecting the best available route.  SD-WAN appliances are often connected to multiple network links to ensure resiliency in the face of a potential outage or service degradation of a provider’s network. 

MPLS Overview 

MPLS uses dedicated links between corporate locations and routes traffic more efficiently than traditional IP-based routing, avoiding public internet connectivity and providing reliability and performance guarantees for corporate WAN service. MPLS service level agreements (SLAs) ensure a certain level of performance and uptime. 


Advantages of MPLS over SD-WAN 

MPLS is a more established technology and provides the following benefits: 

Reliability 

Dedicated links between corporate locations ensure reliability by avoiding public internet. This directly contrasts SD-WAN, which uses public Internet to carry WAN traffic where reliability is determined based on the underlying public Internet infrastructure. 

Quality of Service 

MPLS defines classes of service that prioritize certain traffic types and take full advantage of performance guarantees while deprioritizing less important traffic dependent on low-latency connectivity. 

SD-WAN also implements quality of service (QoS) policies and prioritizes certain traffic types. However, even with QoS, SD-WAN is dependent on the public internet and provides lower performance guarantees than MPLS. 

Security 

A major advantage of MPLS is the security gained through dedicated WAN links between corporate locations. On the other hand, SD-WAN creates a virtual overlay on top of existing networks. Access controls and security protections are implemented at the software level, exposing WAN traffic to software vulnerabilities and other potential cyber threats. 


Advantages of SD-WAN Over MPLS 

Cost Effectiveness 

As a virtual overlay on top of existing network infrastructures, SD-WAN is much more cost-effective than having dedicated links. 

Application Visibility & Control 

As a self-managed or co-managed solution, SD-WAN provides visibility and control of applications flowing over the network. MPLS, being fully managed by the telco, does not provide self-management or co-management options, which are not provided to the organization. 

Availability 

SD-WAN performs continuous link health checks and route optimization, allowing it to adapt to a variety of network conditions and avoid network outages. MPLS, on the other hand, is tethered to dedicated links. So, an outage will adversely impact the corporate WAN service. 

Flexibility and Scalability 

As a virtual overlay network, SD-WAN is more flexible and adaptable to change as network and business requirements evolve. MPLS is very rigid and requires a service ticket with the telco for network changes or capacity growth requirements. 

Simplified Management 

Most SD-WAN deployments are cloud-managed and provide a centralized view of the network, making it easier to manage than MPLS. 

Granular Control 

Granular visibility of the network is a key benefit of SD-WAN, and this enables organizations to define application-specific rules and policies for a higher level of control. MPLS, while providing QoS capabilities, lacks the same granularity of control of SD-WAN. 

Cloud Support 

SD-WAN makes it easy to provide connectivity between branch locations and cloud data centers while maintaining visibility and control over the corporate WAN. MPLS was not designed to deliver cloud services, which forces organizations to backhaul traffic through the corporate data center before routing to cloud-based applications. As a result, this traffic experiences increased latency, which negatively impacts application performance and user experience. 

Advanced Security 

Both SD-WAN and MPLS provide a certain level of security for WAN traffic. However, neither solution offers the native security capability to inspect network traffic for advanced threats. As a result, organizations must deploy a separate network security solution to ensure that all traffic is protected. 


The Case for Either MPLS or SD-WAN 

MPLS and SD-WAN are both effective corporate WAN solutions, and neither is inherently superior to the other. The right decision on technology depends on an organization’s unique business needs. 

When to Choose MPLS 

The primary advantage of MPLS over SD-WAN is the performance and reliability guarantees that are backed by SLAs. SLA guarantees make MPLS a better choice for latency-sensitive, mission-critical applications. 

Another argument for MPLS over SD-WAN is compliance and security. The dedicated connectivity of MPLS provides better security than SD-WAN. 

When to Choose SD-WAN 

SD-WAN offers improved cost-effectiveness, flexibility, scalability and availability. Depending on the underlying physical infrastructure, SD-WAN can also provide improved performance and reliability when compared to MPLS; however, these are not necessarily backed by SLAs as with MPLS. 

SD-WAN is likely a superior alternative to MPLS for any use case that doesn’t require an SLA-backed guarantee. For example, an organization may use SD-WAN for non-business-critical applications and integrate with MPLS for business-critical or latency-sensitive applications. Policies can then be used to ensure that MPLS connectivity is available to those applications. 


MPLS to SD-WAN Migration 

For most companies, making the move to SD-WAN is a logical choice. It offers comparable performance and reliability to MPLS in most cases. While SD-WAN is only as reliable as the public internet, it is still a more flexible alternative for organizations in dynamic growth mode or pursuing digital transformation initiatives. 

Cato offers the SLA-backed guarantees of MPLS combined with the dynamic flexibility of SD-WAN. Cato SD-WAN runs on top of a network of dedicated, Tier-1 carrier links, ensuring better performance than SD-WAN over the internet. Additionally, Cato customers can simplify the transition to and management of their SD-WAN deployment with SD-WAN as a Service. 

SD-WAN FAQ

  • What is SD-WAN?

    Software-defined Wide Area Network (SD-WAN) devices sit in company locations and form an encrypted overlay between themselves across any underlying transport service including MPLS, LTE, and broadband Internet services.

  • What are the benefits of SD-WAN?

    Reduced Bandwidth Costs: MPLS bandwidth is expensive. On a “dollar per bit” basis, MPLS is significantly higher than public Internet bandwidth. Exactly how much more expensive will depend on a number of variables, not the least of which is location. However, the costs of MPLS aren’t just a result of significantly higher bandwidth charges. Provisioning an MPLS link often takes weeks or months, while a comparable SD-WAN deployment can often be completed in days. In business, time is money, and removing the WAN as a bottleneck can be a huge competitive advantage.
    Reliable Network Across the Unreliable Internet: The ability to connect locations with multiple data services running in active/active configurations. Sub-second network failover allows sessions to move to new transports in the event of downtime without disrupting the application.
    Secure Communications: Encrypted connectivity secures traffic in transit across any transport.
    Bandwidth on Demand: The capability to immediately scale bandwidth up or down, so you can ensure that critical applications receive the bandwidth they need when they need it.
    Immediate Site Activation: Bring up a new office in minutes, instead of weeks and months that it takes with MPLS. SD-WAN nodes configure themselves and can use 4G/LTE for instant deployment.

  • What are the key trends driving SD-WAN adoption?

    Enterprises built their networks using legacy carrier services, such a managed MPLS service. These services are expensive, require weeks to months to activate sits, and require waiting for the service provider to make even the simplest of changes.
    SD-WAN offers an escape from that bringing agility and cost efficiencies to IT networking. The SD-WAN connects locations with several Internet connections, aggregating them together with an encrypted overlay. Policies, application-aware routing, and dynamic link assessment in the overlay allow for the optimum use of the underlying Internet connections.
    Ultimately, SD-WAN delivers the right performance and uptime characteristics by taking advantage of the inexpensive public Internet with the security and availability needed by the enterprise.

  • What are the limitations of SD-WAN?

    Lack of a global backbone: SD-WAN appliances sit atop the underlying network infrastructure. This means the need for a performant and reliable network backbone is left unaddressed by SD-WAN appliances alone.
    Lack of advanced security features: SD-WAN appliances help address many modern networking use cases, but don’t help with security requirements. As a result, enterprises often need to manage a patchwork of security and networking appliances from different vendors (Like CASBs) to meet their needs. This in turn leads to increased network cost and complexity as each appliance must be sourced, provisioned, and managed by in-house IT or an MSP.
    No support for the mobile workforce: By design, SD-WAN appliances are built for site-to-site connectivity. Securely connecting mobile users is left unaddressed by SD-WAN appliances.