SD-WAN vs MPLS: Will SD-WAN lead to the demise of MPLS?

When SD-WAN first came along, there was a lot of hype surrounding it; people said it was far superior to MPLS and that its rise would lead to the ‘death’ of MPLS. However, this so far hasn’t happened. In order to understand why, and if one is in fact better than the other, it’s important to understand what the difference is between the two.

MPLS, or multiprotocol label switching, is a traffic routing technique. With MPLS, packets are assigned labels when they first enter the network. The labels pre-define a highly efficient route for the packet to be sent through the network. This means that the packet doesn’t need to be analysed at each router to decide where it will go next.

SD-WAN is the application of software-defined networking (SDN) technology to wide area network (WAN) connections. With SD-WAN, networking hardware can be managed by a software-based controller, which can be hosted in the cloud.

In short, SD-WAN is an overlay technology, whereas MPLS is one of the options to provide connectivity to an SD-WAN network, and sits underneath as an underlay. To say that one’s better than the other, or that one must be chosen over the other is wrong, because they are not opposing solutions; they can actually be complementary. In order to decide which is appropriate for your business, or if the best solution would be both of them, it’s useful to consider the pros and cons of each option.

 

MPLS

Pros

  • MPLS prioritises network traffic. Assigning a label to each packet makes it easy to identify the particular characteristics of that packet, and assign it an appropriate route accordingly. This means that packets with real-time traffic (e.g. video or voice) can be given a higher priority, and get sent along the lower-latency routes. That way, MPLS is able to provide a better end-to-end Quality of Service (QoS).
  • Reliable packet delivery avoids packet loss, which maintains data quality
  • MPLS is private and does not require additional security and encryption, unlike SD-WAN. Think of it as a secured tunnel running through an already secured network.

Cons

  • MPLS is expensive! It has a high cost per megabit, which is particularly problematic when you consider the increasing demands on data (high-quality video streaming, gaming, AR/VR applications etc.)
  • MPLS can be less secure than SD-WAN (we’ll discuss this a little more in the next section). When compared to SD-WAN, MPLS does not have data protection isn’t built in. Although data is separate from the public internet (since MPLS is a virtual private network) so generally considered to be secure, SD-WAN solutions can enhance security by adding it as an overlay solution to provide superior security.
  • It’s difficult to find MPLS providers who provide global coverage – usually they must partner with other service providers which is an additional cost

SD-WAN

Pros

  • SD-WAN is very cost effective as it enables you to mix and match network links depending on the quality or speed requirements of the content; you can use cheaper routes such as LTE or broadband for lower-priority traffic, and MPLS for higher priority traffic
  • SD-WAN is provider agnostic, so the benefits are the same regardless of which Internet Service Provider you use. This allows you to avoid vendor lock-in.
  • SD-WAN is more flexible and easier to upgrade – there are no bandwidth penalties so customers can easily add new links without needing to make changes to the infrastructure / network

Cons

  • SD-WAN is slightly less reliable than MPLS, so jitter and packet loss are possible
  • In theory, SD-WAN can be more secure than MPLS only if security is integrated into the solution, for example with end-to-end encryption across the entire network, stringent authentication controls etc. However, in reality, there are SD-WAN solutions out there that only provide the basic security functionality.

Overall, the answer to the question of which is better is: it depends. Since they’re not the same thing it’s difficult to compare them directly, but on the whole SD-WAN can be thought of as cheaper and more flexible, while MPLS offers better reliability. When deciding which to use you must consider what your needs are; it could be that the best solution is to use both.

So will SD-WAN lead to the demise of MPLS? It’s true that increased use of SD-WAN could lead to a decrease in demand for MPLS, since SD-WAN makes it easier to use alternatives to MPLS. But instead of seeing SD-WAN as a replacement for MPLS, you could also see it as a way to augment legacy MPLS services.

Going back to security, it is not a matter of SD-WAN vs. MPLS, both can work together in a complementary way and the combination of the two can ensure that your data is safe and secure. For example: You can still have critical transactions running over MPLS.

Our point is… we won’t dispute that demand for MPLS is and will decrease over time but there will continue to be demand for MPLS from businesses with special connectivity requirements, like for mission critical or real-time applications, so MPLS won’t be going anywhere anytime soon.

Author: Miran Gilmore, Consultant

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