Dec 04, 2019

Is SD-WAN for everyone? Almost!

  • Article
  • SD-WAN
  • WAN
  • WANs
  • networks

The digital revolution is transforming how we work and communicate. It’s also changing how we connect and manage links between buildings using wide area networks (WANs) and software-defined WANs (SD-WANs). In an SD-WAN, the WAN is defined dynamically by a software layer that sits on top of the standard telecommunications links.

But many wonder whether an SD-WAN solution is right for them and whether it will really reduce their connectivity costs. Let’s take a closer look at these questions.

  1. What’s an SD-WAN service?

    An SD-WAN service is based on at least two types of technology: dynamic bandwidth allocation over multiple links and centralized management of these links.

    A number of manufacturers claim their SD-WAN equipment will save you a lot on your telecommunications links. However, three variables must be considered:

    • The cost of telecommunications links depends on the medium used. The most common media are dedicated fibre optics, coaxial, shared fibre optics (FTTH or FTTN), and LTE.
    • The type of service delivered. The SD-WAN approach can be used with an Internet service (dedicated fibre optics “DIA” dedicated internet access, shared fibre optics, coaxial or LTE) or a private network service, such as multiprotocol label switching (MPLS).
    • The region where the telecommunications links are installed.

    The two key variables are the medium and the region. For example, to reduce costs, your company may decide to replace a dedicated fibre optics link with a shared fibre link or with a less costly coaxial network. However, you need to assess how these changes affect your network’s performance, since the SD-WAN service does not alter the characteristics of the medium and the technology used by the telecommunications service provider (TSP) to deliver this type of service.

    What’s more, if your company has locations in the United States and you decide to replace an MPLS link on dedicated fibre optics with an Internet link on dedicated fibre optics, you should be aware that American TSPs tend to charge more for MPLS-type services than for Internet services on a comparable medium. As this is not always the case in Canada, it may represent a worthwhile savings, in my view.

    SD-WAN and performance

    Another important aspect is that manufacturers sometimes fail to mention how SD-WAN actually affects WAN performance. In fact, a dedicated fibre service has latency features that shared services cannot deliver. Additionally, this type of link generally comes with clear service guarantees and response times, which shared links do not

    Further, some manufacturers install functionalities using a software layer while others choose a “hardware accelerated” layer. If your company chooses an SD-WAN manufacturer and selects an option with a software layer, this may have an impact on service performance.

    And, as always, never overlook the security aspect. Certain manufacturers offer an SD-WAN solution that is functionally complete but less powerful in terms of security. Also, if you replace a private MPLS network with an SD-WAN solution via Internet services, more equipment is exposed to the inherent risks of a public network and the potentially greater complexity of updating microcode to mitigate security weaknesses.

    The final element to consider when implementing an SD-WAN service is the type of architecture. There are currently three types of SD-WAN architecture:

    • Premises-based: all equipment is located on site, including the SD-WAN hubs.
    • Cloud-enabled: the hubs are in the cloud, under the manufacturer’s umbrella, or virtualized with a cloud service like Amazon Web Services (AWS).
    • Cloud-enabled plus backbone: this architecture is available from TSPs, which makes them responsible for SD-WAN hubs.

    To conclude

    In conclusion, before embarking on a project to evaluate or implement an SD-WAN architecture, you need to determine your objectives and priorities based on the elements listed in this article. This will ensure the architecture actually meets your needs.

    Below is a brief summary of the benefits and drawbacks of an SD-WAN.


    • Agility
    • Dynamic allocation of bandwidth over multiple links
    • Routing by application
    • Visibility
    • Centralized management
    • Deployment that requires no user action


    • More equipment and licenses
    • More equipment exposed to the Internet
    • No quality of service (QoS) level in the backbone without MPLS link
    • Real-time application possibly affected
    • No level 2 service natively

    At the end of the day, a hybrid solution may be better suited to your business needs. Contact us to find out more!

This content is for general information purposes only. All rights reserved ©BBA

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