SD-WAN vs. MPLS: Which One Should I Choose?

SD-WAN is an emerging technology that promises to revolutionize wide area network connectivity (WAN) by providing enterprises with the ability to automatically choose lower-cost paths between branch offices while buttressing high availability and performance. These benefits are very appealing to enterprises that have long struggled with expensive WAN links between sites, not least in multiprotocol label switching (MPLS) networks where bandwidth costs are significant.

However, the adoption of SD-WAN deployments in MPLS networks is not always straightforward given that it challenges conventional wisdom about how WAN network connectivity should be designed and provisioned. This article discusses SD WAN vs MPLS. We describe some of these issues and includes design guidance for implementing both primary and backup paths between the enterprise edge routers that support an SD-WAN deployment.

What is SD-WAN & SD WAN Solutions

Software-defined WAN (SD-WAN) is a network service that enables enterprises to create cost-effective, dynamic networks by deploying intelligent networking applications on commodity hardware and routing traffic over broadband internet and mobile networks. In an SD-WAN solution, all internet working functions are managed by software instead of conventional hardware appliances, resulting in significant capital and operating expense savings for the enterprise.

SD WAN solutions are designed to address network performance issues, mainly congestion and packet loss problems by replacing or enhancing traditional branch routers with virtual applications that can control policies and offer a network overlay of the less expensive internet options. SD WAN has many use cases but put simply a business with SD WAN adoption can provide remote or decentralized locations direct internet access. A major plus with a ever increasing work force working from home in the age of COVID.

What is MPLS?

Multiprotocol Label Switching is a networking technology based on the label swapping forwarding paradigm. MPLS creates a hierarchy of label switched paths (LSPs) within a network by assigning to each LSP a unique label and associating that label with a particular path, or route between two nodes. In the simplest sense, MPLS labels are used to forward packets across an MPLS network toward their destinations.

Key Differences Between SD-WAN and MPLS

The key differences between SD-WAN and MPLS can be summarized as follows:

1. WAN cost savings – In the SD-WAN model, enterprises will get lower WAN costs by adopting commodity hardware for some of their enterprise edge routers, which will terminate the less important SD-WAN links instead of more expensive MPLS links. In contrast, MPLS networks do not provide any significant cost savings over the Internet in most cases because Internet bandwidth has become quite inexpensive in recent years.

2. Bandwidth scalability – SD-WAN is a more scalable WAN architecture than MPLS because of its ability to automatically adjust to changing traffic patterns and performance requirements without manual provisioning.

3. High availability – SD WAN service providers can offer improved resiliency with an SD-WAN solution because they can allocate increased capacity to the less important links between enterprise sites, making it possible for them to survive even if one of their MPLS or private WAN circuits fails. This is not the case with traditional MPLS networks, in which a failure in any part of the network will take down all links between sites.

4. Flexibility – MPLS networks are not flexible enough to work with next-generation data centers that have adopted technologies such as overlay networking and micro-segmentation, because they typically require special hardware appliances for advanced features such as east/west traffic isolation.

5. Network management – MPLS networks are extremely complex to manage because of the sheer number of devices, circuits, and peers required to provide them correctly. SD-WAN simplifies network management by moving away from manual provisioning towards fully automated mechanisms that automatically select the best paths between sites according to real-time performance metrics such as throughput and packet loss.

6. Security – SD-WAN solutions can provide more effective security than MPLS because they consolidate routing, switching, WAN optimization, firewalling, VPNs/VTI services, etc., on a single platform so they can work together to form secure networking constructs automatically instead of requiring manual provisioning and intervention as is the case with MPLS.

SD-WAN Architecture & How it Works
From cosgrid.com – showing differences between SD Wan and MPLS

Does SD-WAN Replace MPLS?

While there is still some controversy about whether an SD-WAN solution will generally be able to replace existing MPLS links, it is clear that in most cases, an enterprise with a multi-site network will eventually adopt both technologies because each one fills some of the gaps that the other does not.

An MPLS network makes sense in most cases because it provides highly reliable and scalable connectivity across multiple sites, while an SD-WAN solution offers cost savings by working more efficiently with commodity hardware and a simplified management interface for a single site or a small number of sites.

Benefits of MPLS for Your Business

Without any doubt, MPLS is currently the most popular and widely used architecture for enterprise WANs since it has been around, and it will remain so in the foreseeable future because of its reliability and scalability.

Even though SD-WAN is a promising technology that promises more cost savings than MPLS networks while also offering better flexibility and simplified management, it is not mature enough to replace MPLS in many cases.

MPLS technology will therefore remain the mainstream WAN architecture for enterprise networks in the foreseeable future because of its longstanding presence and proven track record.

Is SD-WAN Worth it for Your Business?

Regardless of the fact that a lot of businesses will continue to rely on traditional MPLS networks, there is still a great deal of interest in SD-WAN solutions because they promise more cost savings and better flexibility than conventional MPLS networks.

While most businesses cannot afford to replace their existing MPLS links with an SD-WAN solution just yet, it is important to consider these solutions as future alternatives because they can support a wide range of advanced features that MPLS networks do not provide.

As the technology matures and becomes more reliable and scalable, we will see more and more enterprises adopting SD-WAN to replace their existing MPLS links for cost reasons while also taking advantage of the advanced features that only SD-WAN solutions can offer.

SD WAN vs MPLS Summary

Using MPLS technology to build your enterprise network infrastructure is still the most effective way to deliver highly reliable and scalable connectivity across multiple sites.

However, SD-WAN is a promising technology that offers more flexibility and cost savings than traditional MPLS networks while also providing advanced features such as east/west traffic isolation.

Regardless of whether they are currently an MPLS customer or not, it is important that businesses consider SD-WAN as a worthy alternative to MPLS networks because of their growing popularity and improved capabilities.

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