In this three-part series, we examine why software-defined WAN (SD-WAN) has risen to be so popular. We also answer all the questions you wanted to ask about SD-WAN, including what it is, what challenges it solves, the benefits and approach you should take when considering a SD-WAN deployment.

So, you’re considering implementing software-defined WAN (SD-WAN) in your organisation, but not completely sure whether you need it?

Taking a self-assessment approach is a good place to start – here are the top five questions to ask in order to understand whether SD-WAN is the right communications architecture approach.

1. Do you plan to increase the number of cloud apps or services you use?
Increasing cloud-based apps will impact traffic patterns. SD-WAN can securely direct a portion of your traffic from the branch to go straight to the cloud via public internet links, giving a better user experience  if you don’t have many resource-hungry apps at the branch.

However, SD-WAN may not be ideal for the following reasons:

  • You have large numbers of branch offices, as SD-WAN products are optimised for fewer than 200 users.
  • Your WAN is mainly single-homed locations, which means you lose the benefits of dynamic path selection and application-centric routing.
  • High latency WAN which degrades application performance, as many SD-WAN products do not include WAN optimisation.

2. Do you have remote users affected by bandwidth issues?
It’s difficult to ramp-up bandwidth with traditional communications architectures such as MPLS. SD-WAN solves this by letting you flexibly manage traffic routing based on business policy. Path control can be automated, and path quality determined by available bandwidth, latency, jitter, or packet loss.

3. Do you need to support a digital transformation project/customer experience?
Unlike traditional WAN technologies, SD-WAN decouples the network and control plane and utilises a software-defined approach, making it easier to adapt to the changing demands of application delivery and business requirements. SD-WAN includes integrated monitoring across the to improve the overall digital experience.

4. Do you need to improve the security of direct internet access?
SD-WAN allows you to limit network attack surfaces that prevents a breach at one branch affecting others. You can secure your public and private connections using embedded firewalls and VPNs, while network segmentation can let you select traffic paths for each application and type of data depending on business priority and security needs.

5. Is your organisation growing?
SD-WAN lets you set up new branch offices easily and cheaply as it requires no travel or on-site configuration.  Using SD-WAN you can bring appliances online automatically by using centralised policy rules. You can also automate cloud connectivity and deliver unified cloud policy across regions cloud service providers.

Moving forward with SD-WAN
Now that you have determined whether SD-WAN suits your organisation’s needs, the next step is to evaluate products and providers. The following is a sample of Gartner’s Toolkit: RFT Template for SD-WAN Products and Services suggested questions to consider. This template will help you create a decision map to make the right choice for your application.

  • What is your scale and architecture? (ie:  minimum and maximum number of remote branches?) Consider network-based infrastructure (points of presence) and where/how the points of presence will be hosted and connected? How is resiliency achieved? How is direct internet access supported?
  • How is management and orchestration capability delivered?
  • Consider your form factors for branch components and deployment options – eg: can they be delivered via physical appliance and/or software? Is the vendors' software available in leading public cloud provider catalogs?
  • Application centricity – eg: how does the solution support cloud-based applications? Does the enterprise have to create its own gateways/hubs, or is the solution integrated into cloud services (both infrastructure as a service [IaaS] and SaaS)?
  • Price – consider three- and five-year total installation/hardware/software/licensing/service/support costs. What level of visibility and security is available?