In the progressive and fluctuating world of networking technologies, the debate between traditional Multi-Protocol Label Switching (MPLS) and the emerging Software-Defined Wide Area Network (SD-WAN) has gained significant traction. MPLS, a stalwart in enterprise networking for over two decades, has provided reliability and performance to organizations worldwide. However, with the advent of cloud computing, the explosion of data, and the demand for flexibility, SD-WAN has risen as a contender, challenging MPLS’s dominance. This analysis delves into the dynamics of MPLS and SD-WAN, exploring their strengths, weaknesses, and potential coexistence in shaping the future of networking.

What is MPLS and how it works?

MPLS, or Multi-Protocol Label Switching, stands as a stalwart in the realm of networking technology, boasting a legacy of over two decades in powering enterprise networks. In stark contrast to conventional network protocols that navigate traffic based on source and destination addresses, MPLS takes a distinctive approach by steering traffic through predetermined “labels.”

Enterprises leverage MPLS primarily to establish connections for remote branch offices seeking access to data or applications situated within the organization’s central data center or headquarters.

The inner workings of MPLS are orchestrated in a manner that sets it apart. Upon a packet’s initial entry into the network, it’s promptly designated to a specific forwarding class of service (CoS), often referred to as a forwarding equivalence class (FEC). This classification is discernible through the addition of a concise bit sequence, popularly known as the “label,” appended to the packet. The nomenclature of these classes often provides insights into the nature of the traffic they encapsulate. For instance, designations like “real time” for voice and video, “mission critical” for CRM or specialized applications, and “best effort” for typical internet or email traffic illustrate the diverse array of applications that can be accommodated.

The strategic allocation of the swiftest, low-latency pathway is meticulously reserved for real-time applications, thus ensuring an elevated quality of service. This precise segregation of traffic based on performance metrics stands as an unparalleled feat that distinguishes MPLS from conventional routing protocols.

A pivotal aspect lies in the architectural brilliance of MPLS—namely, the labels themselves. These labels serve as conduits to embed supplemental information onto each packet, transcending the conventional parameters that routers had previously been confined by.

The question of MPLS’s classification as a Layer 2 or Layer 3 service has engendered some perplexity. MPLS doesn’t neatly conform to the traditional OSI seven-layer model, leading to its occasional categorization as Layer 2.5. A cornerstone of MPLS’s prowess is its knack for segregating forwarding mechanisms from the underlying data-link service, transcending the typical boundaries. This inherent flexibility empowers MPLS to craft forwarding tables that harmonize with an array of underlying protocols.

Functionally, MPLS routers embark on the establishment of a label-switched path (LSP)—a predetermined route designed to channel traffic within an MPLS network, contingent upon criteria within the FEC. The deployment of MPLS forwarding hinges on the establishment of an LSP. Intriguingly, LSPs are unidirectional, signifying that the return journey of traffic traverses an entirely distinct LSP.

Upon an end user’s initiation of traffic into the MPLS network, an ingress MPLS router positioned at the network’s edge promptly appends an MPLS label to the packet. The MPLS label is an assemblage of four integral components:

The Label: Serving as a repository of vital data, the label equips MPLS routers with the intelligence required to chart the course of the packet.

Experimental Bits: These bits assume the role of Quality of Service (QoS) custodians, dictating the priority status accorded to the labeled packet.

Bottom-of-Stack: This component notifies MPLS routers of their status as the final link in the journey, signaling the absence of further label considerations. Typically, this designation signifies that the router functions as an egress point.

Time-To-Live: Representing a paramount metric, this element determines the number of hops a packet can undertake before being discarded, encapsulating an aspect of traffic management crucial to network efficiency.

In essence, MPLS defies conventional networking paradigms, propelling itself as a dynamic and adaptable solution through its nuanced label-based approach.

MPLS: A Reliable Workhorse with Limitations:

MPLS has long been the go-to solution for connecting remote branch offices, ensuring consistent performance for mission-critical applications. Its architecture, based on label switching rather than traditional IP routing, allows for improved bandwidth utilization and reduced network congestion. MPLS segregates traffic into forwarding classes of service (CoS) with distinct labels, enabling prioritization and efficient management of diverse applications. According to a survey conducted by GlobalData, 83% of organizations still rely on MPLS for connectivity, highlighting its entrenched position in enterprise networks.

Despite its reliability, MPLS has inherent limitations. The cost of MPLS connections is notably higher than standard internet connections, making it less feasible for businesses with budget constraints. The rigid architecture of MPLS requires meticulous provisioning and lacks scalability, hindering its adaptability to dynamic cloud-based environments. Furthermore, the hub-and-spoke model of MPLS, once efficient for traffic routed through corporate headquarters, becomes inadequate in the era of direct cloud connectivity. This shift in traffic patterns, coupled with the rise of bandwidth-intensive applications, has exposed MPLS’s inflexibility.

SD-WAN: Flexibility, Cost Efficiency, and Cloud Compatibility:

SD-WAN has emerged as a transformative force in networking, offering agility, cost efficiency, and enhanced cloud compatibility. Its underlying principle of Software-Defined Networking (SDN) empowers network architects to centralize control and apply policies across the WAN. Unlike MPLS, SD-WAN is transport-agnostic, capable of routing traffic through various paths, including MPLS connections. This versatility reduces costs and enhances flexibility, enabling organizations to dynamically adjust to changing demands.

A significant driver of SD-WAN adoption is its cost-effectiveness. A survey by IHS Markit revealed that 82% of respondents consider cost savings as the top SD-WAN benefit. Lightyear’s WAN connectivity pricing guide highlights the substantial difference in costs between MPLS and SD-WAN connections. The average monthly recurring cost of a 100 Mbps MPLS connection is approximately $1,277, while SD-WAN at similar speeds costs only around $300 per month on average. This cost disparity has prompted businesses to consider SD-WAN as a compelling alternative.

MPLS vs. SD-WAN: The Coexistence Paradigm:

The narrative of MPLS vs. SD-WAN is not necessarily a zero-sum game. While SD-WAN gains momentum, MPLS maintains relevance in specific use cases. Small and mid-size businesses, often driven by budget constraints and a shift towards cloud-centric IT models, are more likely to adopt SD-WAN exclusively. On the other hand, larger enterprises with established MPLS networks may opt for a hybrid approach. They retain MPLS for legacy applications requiring on-net performance, while leveraging SD-WAN for internet-bound traffic, such as cloud services.

Verizon’s perspective on the matter acknowledges that SD-WAN can enhance MPLS connections. SD-WAN’s ability to dynamically route network traffic aligns with MPLS’s reliability, offering an optimal quality of service for various applications. This synergistic approach ensures that organizations can extract the most value from their existing MPLS investments while embracing the flexibility of SD-WAN.

The Future of Networking: Pragmatic Choices:

As networking evolves, the future is marked by pragmatic choices that balance performance, cost, and adaptability. While the rise of SD-WAN challenges MPLS’s dominance, it does not spell the immediate demise of the veteran technology. Rather, it prompts organizations to evaluate their networking needs holistically.

Ultimately, enterprises must conduct a comprehensive risk-reward analysis. MPLS guarantees high reliability and performance but at a premium cost, while SD-WAN offers cost efficiency and flexibility but may not guarantee the same level of performance. With advancements in networking technologies and protocols, internet traffic has become more reliable, blurring the line between MPLS and SD-WAN.

Final thoughts

In conclusion, the fate of MPLS and the ascent of SD-WAN signify a pivotal shift in networking paradigms. While MPLS’s stronghold is gradually challenged, its role in connecting specific point-to-point locations and real-time applications endures. The coexistence of MPLS and SD-WAN presents a strategic approach, ensuring that networking choices align with an organization’s specific needs and objectives. In the ever-evolving journey of networking, the crossroads between MPLS and SD-WAN embody the dynamic choices that organizations must make to navigate the digital landscape.