Trade-offs to consider when purchasing SD-WAN from an ISP

In the past few years there has been a lot of talk about software-defined networks (Software-Defined Wide area network, SD-WAN) and now that we are reaching the end of 2017, these products have become so mature that many companies are actually using this technology.

The market is starting to consolidate because of the many providers on the market. Examples of this are Cisco acquiring Viptela and VMWare buying Velocloud. Some SD-WAN providers have opted to focus on network operators, which is a good market for them. Is it a good idea for you as a customer to buy a SD-WAN network from an ISP?

The biggest advantages of buying from an internet service provider (ISP) are:

  • The ability to buy from a provider with whom you already have established a business relationship
  • New functionality in your WAN without you having to push through a change yourself
  • Responsibility for the WAN remains with the operator
  • Fewer demands for competence and resources from within your own organisation

What are usually the main reasons for building an SD-WAN?

  • Cost – The biggest reason to get SD-WAN is to reduce your WAN costs. The cost of a WAN accounts for a significant portion of the total IT cost.
  • Ownership of the WAN – The company wants to own the WAN to make changes and start new offices more quickly.
  • Transport-agnostic – The purpose of SD-WAN is to be transport-agnostic, meaning that you can build your WAN over any type of transport that meets your needs and suits your cost profile.
  • Intelligent routing – Traditional routing protocol does not permit routing based on a connection’s performance, such as latency, jitter and packet loss without advanced configuration.

Let’s now think through these four main reasons and how a SD-WAN network from an ISP relates to them.

  • Cost – When you purchase an SD-WAN network from an ISP you do not have the full freedom to build your WAN over your choice of service provider. The biggest cost of WAN is for the connection. You give up the right to compare ISPs and negotiate the best possible price.
  • Ownership of the WAN – An SD-WAN network from an ISP means that you do not own your WAN. How quickly can you add a new office? Do you have access to equipment? How much time do you need to implement a change? These are important parameters to consider if you outsource your WAN.
  • Transport-agnostic – If you buy from an ISP you do not have the freedom to choose the ISP you want, and which is available in a specific region. This can make it more difficult and expensive to find a suitable way to connect.
  • Intelligent routing – You will have intelligent routing, but only on those transports available from the ISP you’re buying the service from.

There are some clear disadvantages with buying the service from an ISP. Here are a few more factors to consider:

  • Complexity – A good SD-WAN product should be easy for the company to manage without needing to rely on an external party. With the amount of money being saved on buying your own WAN, it might be worth investing in the competence of your own staff.
  • Agility – How fast can an ISP respond to your requests? How important is your company to the ISP?
  • Competence – ISPs don’t always attract the top talents out there because there are only a few interesting roles available, and a big part of the work involves answering customer calls and keeping the business going, and not so much developing services.
  • Blame Game – Sure, you seem to have only one throat to choke, but will the ISP take full responsibility for solving problems or will they blame the SD-WAN provider when things go wrong?
  • Fate Sharing – What happens when the ISP has a major outage? What is the use of your SD-WAN if the connection is down or not running well enough to handle your traffic? You may think that you are safe if you purchase MPLS, but if your ISP gets DDoSed over the internet, think again.

There are pros and cons to all business models but giving up ownership and hence the cost of your WAN in the modern era of networking is risky. If you decide to outsource your WAN, make sure that you have a plan to handle the above scenario. If you think that IT is not your core business, you are probably wrong, but that is a topic for another chapter. Best of luck with your SD-WAN plans and remember that there are trade-offs with every design. If you have not found them, you have not looked hard enough.

My colleagues and I are ready to answer your questions about the best choice of network for your business, contact us.

By Daniel Dib, Senior Network Architect, Conscia, CCIE #37149, CCDE #20160011