SD-WAN vs. Traditional WAN: What’s Right for Your Data Center Interconnect

SD-WAN vs. Traditional WAN: What’s Right for Your Data Center Interconnect?

Connecting distributed enterprise resources – data centers, branch offices, remote users, and cloud platforms – requires a robust and efficient Wide Area Network (WAN). For decades, traditional WAN technologies, particularly Multiprotocol Label Switching (MPLS), have been the mainstay for providing reliable, high-performance connectivity.¹⁰⁸ However, the rise of cloud computing, the need for greater agility, and pressure to control costs have exposed the limitations of these legacy approaches.⁹⁸

Backhauling cloud-bound traffic through a central data center over expensive MPLS links is inefficient and costly.¹⁰² This has paved the way for Software-Defined WAN (SD-WAN), a modern approach that promises more flexibility, better cloud integration, and potential cost savings.⁹⁸ But is SD-WAN always the right choice, especially for critical Data Center Interconnect (DCI) links? This post compares SD-WAN with traditional WAN (primarily MPLS) to help you determine the best fit for your needs. Intelligent Visibility offers expertise in both traditional and modern WAN solutions, including SD-WAN and SASE.¹⁵

Understanding the Contenders: SD-WAN vs. MPLS/Traditional WAN

It's important to understand the fundamental differences:

• Traditional WAN (MPLS Focus):

• • Architecture: MPLS operates at the underlay level, creating private, dedicated paths across a service provider's network using label switching rather than traditional IP routing for forwarding decisions.¹⁰⁸ It relies heavily on the provider's physical infrastructure and hardware.⁹⁸ Traffic typically follows predetermined paths.¹¹¹

  • Key Strength: High reliability and predictable performance (low latency, jitter, packet loss) often backed by Service Level Agreements (SLAs).¹⁰⁴ Considered inherently secure due to its private nature (though encryption is often an add-on).¹⁰⁴

  • Common Use Cases: Mission-critical applications requiring guaranteed QoS (like VoIP, video conferencing), connecting major sites with high reliability needs, industries with strict data privacy requirements.¹⁰⁴

• SD-WAN (Software-Defined WAN):

• • Architecture: SD-WAN operates as a virtual overlay network, abstracting the control plane from the underlying hardware.⁹⁸ It uses a centralized controller (orchestrator) to manage policies and traffic routing across multiple available transport types (underlays), which can include MPLS, broadband internet, LTE/5G, etc..⁹⁸

  • Key Strength: Flexibility and Agility. It can dynamically steer application traffic over the best available path based on real-time network conditions and predefined policies (application-aware routing).⁹⁸ Centralized management simplifies configuration and policy deployment across many sites.⁹⁸ It facilitates direct cloud access (local internet breakout) and often integrates security features (forming the basis of SASE).⁹⁹

  • Common Use Cases: Connecting branch offices, optimizing cloud application performance, reducing reliance on expensive MPLS circuits, improving network agility, enabling secure remote access.⁹⁸

The "SD-WAN vs. MPLS" debate is somewhat misleading, as SD-WAN is an overlay technology that can utilize MPLS as one of its underlay transport options.¹⁰⁸ Many organizations adopt a hybrid approach, using MPLS for critical site-to-site traffic requiring guaranteed performance and SD-WAN over internet links for cloud access and less critical traffic.¹¹²

Feature Comparison: Performance, Cost, Security, Management

Let's break down the key differences impacting DCI decisions:

• Performance & Reliability: MPLS offers predictable performance due to its private nature and traffic engineering capabilities.¹⁰⁴ SD-WAN performance, however, is heavily dependent on the quality of the underlying internet connections.¹⁰⁰ While SD-WAN uses techniques like path selection, forward error correction, and application prioritization to optimize performance over less reliable links ¹⁰², it may not match the guaranteed QoS of MPLS for highly sensitive real-time traffic without a high-quality underlay.¹⁰⁰ However, SD-WAN can enhance reliability by utilizing multiple diverse links (e.g., broadband + LTE) with automated failover.¹⁰²

• Cost: SD-WAN typically offers significant cost savings compared to MPLS.⁹⁸ This stems from leveraging lower-cost internet bandwidth instead of expensive dedicated MPLS circuits.⁹⁸ Setup costs for MPLS are also generally higher due to circuit provisioning times and specialized hardware.¹¹⁹ SD-WAN often uses commodity hardware or virtual appliances and benefits from zero-touch provisioning.¹⁰³ Over time, SD-WAN can reduce network TCO significantly.²¹⁵

• Scalability & Agility: SD-WAN excels here. Adding new sites or increasing bandwidth is much simpler and faster with SD-WAN's software-defined approach compared to the lengthy provisioning cycles for MPLS circuits.⁹⁹ Centralized policy management allows rapid deployment of configuration changes across the entire network.⁹⁸

• Security: While MPLS is private, it doesn't inherently include encryption.¹⁰⁴ SD-WAN overlays typically use encrypted tunnels (like IPsec).²¹⁴ Furthermore, SD-WAN solutions increasingly integrate comprehensive security stacks (NGFW, SWG, CASB, ZTNA) as part of a SASE architecture, providing unified security policy enforcement across the WAN.⁹⁹

• Management: SD-WAN's centralized controller/orchestrator simplifies management compared to the device-by-device configuration required for traditional routers in an MPLS network.⁹⁸ Automation features like zero-touch provisioning streamline deployment.²¹⁶

SD-WAN for Data Center Interconnect (DCI)

While often associated with branch connectivity, SD-WAN is increasingly considered for DCI use cases:

• Benefits:

• • Cost Savings: Replacing or augmenting expensive high-bandwidth MPLS DCI links with SD-WAN over dedicated internet access (DIA) or multiple broadband links can reduce costs.⁹³

  • Flexibility: Easily connect data centers across diverse geographical locations and integrate them with cloud environments.⁹²

  • Optimized Cloud Access: Facilitates efficient routing between data centers and multiple cloud providers.⁹²

  • Centralized Management: Simplifies managing connectivity policies between multiple data centers.⁹³

  • Enhanced Security: Integrated security features can provide consistent policy enforcement for inter-DC traffic.⁹²

• Considerations:

• • Performance Sensitivity: For extremely low-latency or jitter-sensitive applications between data centers (e.g., synchronous replication, high-frequency trading), the predictability of dedicated circuits (MPLS or dark fiber) might still be preferred over internet-based underlays, even with SD-WAN optimization.⁹³

  • Underlay Quality: The reliability and performance of the SD-WAN overlay for DCI is directly dependent on the quality and diversity of the underlying transport links.¹⁰⁰ Using high-quality DIA or multiple diverse internet connections is crucial.

  • Scalability: Ensure the chosen SD-WAN solution can handle the high throughput demands typically associated with DCI.⁹⁴

Intelligent Visibility: Guiding Your WAN Strategy

Choosing the right WAN architecture for your data center interconnect and overall enterprise connectivity is a critical decision. Intelligent Visibility provides expert guidance and solutions tailored to your specific needs.¹⁵

We offer:

• SD-WAN Expertise: Design, deployment, and management services for leading SD-WAN platforms, including solutions like VMware SD-WAN (formerly VeloCloud) and Palo Alto Networks Prisma SD-WAN (leveraging prompt keywords and iVi's SASE/SD-WAN solution area ¹⁵).

• Hybrid WAN Integration: Expertise in integrating SD-WAN with existing MPLS networks for optimized performance and cost.

• SASE Implementation: Integrating security seamlessly with your SD-WAN for a unified, cloud-delivered security posture.¹⁵

• Network Automation: Leveraging automation for zero-touch provisioning and simplified policy management across your WAN.¹⁵

• Managed Services: Our Aegis services provide ongoing management, monitoring (Aegis PM), and incident response (Aegis IR) for your WAN environment.¹⁵

Conclusion: Choosing the Right Path Forward

The choice between SD-WAN and traditional WAN (MPLS) for DCI and broader enterprise networking is not always clear-cut. MPLS remains a viable option for scenarios demanding the highest levels of predictable performance and reliability. However, SD-WAN offers compelling advantages in terms of cost-efficiency, flexibility, scalability, cloud integration, and centralized management, making it an increasingly attractive solution for many organizations, including DCI use cases when implemented with appropriate underlay considerations. Often, a hybrid approach leveraging the strengths of both technologies provides the optimal balance. Evaluating your specific application requirements, performance needs, security posture, and budget is key to making the right decision for your organization's future.

Next Steps:

How can you ensure your data center network is truly ready for the future?

• Read Post 7: Future-Proofing Your Data Center: Scalability, Security & Sustainability

• Contact Intelligent Visibility: Discuss your WAN modernization challenges and explore SD-WAN or hybrid WAN solutions.