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Over the last year or two, software-defined WANs (SD-WANs) have become a very hot topic with numerous vendors currently offering SD-WAN products. If you've decided on an SD-WAN architecture, having such a breadth of products to choose from is a classic good news/bad news situation. The good news is that if you don't like a particular vendor's product, there are a lot of others available. The bad news is that network organizations must now evaluate a broad range of SD-WAN technology offerings, all of which claim to be the best, in order to identify the one that is the optimum fit for their requirements.
Give it a one-two analytical punch
I advise my clients who are considering an SD-WAN architecture to evaluate products through a two-phase analysis. The first phase is a somewhat cursory evaluation of a number of products, the goal of which is to identify a small set of feasible ones. The second phase is a detailed analysis of that small set of products that, in most cases, includes performing a proof of concept (trial of one or more.
The focus of each stage of a WAN architecture analysis has to be on two things:
- What goals are your organization trying to meet by changing your approach to wide area network architecture?
- How well do each of the SD-WAN candidates help you achieve those goals?
For the sake of example, assume your organization has four goals:
- Increase security
- Provide access to public cloud services
- Improve application performance
- Reduce cost
One of the primary ways of determining whether or not an SD-WAN tool can meet these four goals is to evaluate its architecture. That's a critical task, because in contrast to a traditional WAN, a SD-WAN architecture contains more places to host functionality. Those locations include the following:
- At the customer's branch offices;
- In a service provider's central office;
- At the customer's data centers;
- In a cloud site the SD-WAN vendor provides;
- At a colocation facility; and
- At a public cloud provider's facility.
Stick with the four goals listed above as part of the overall analysis you need to determine several things. First, what security functionality is provided and what are the options for where it is hosted? Next, determine what functionality (e.g., security, optimization, management) can be provided at a public cloud provider's facility.
Once those first few determinations are made, you need to evaluate how the SD-WAN product improves application performance. For example, does it provide any optimization? If so, what functionality does it deliver, and what are the options for where that functionality is hosted?
Another issue to consider is how the product reduces cost. Is it just by using lower-cost Internet services? Does the product also enable you to eliminate appliances such as routers?
Follow up with a POC
As mentioned, in most cases the second stage of analysis should include a proof of concept. One of the keys to conducting a successful POC is to choose the branch offices in such a way that they are representative of all of the company's branch offices. Another key to making this approach successful is to minimize risk. One way to minimize risk is to implement the trial in an incremental fashion, whereby the new wide area network architecture is first implemented in just a very few offices. If the new product works well, the trial can be quickly expanded to other offices.
Assuming that the analysis goes well and that you want to implement an SD-WAN architecture, you can either do that yourself or acquire the requisite tool as a managed service from a carrier. The primary reason that an organization would want to acquire a managed SD-WAN product instead of implementing it themselves is cost.
To determine if the managed service actually costs less, you have to be able to determine what it would cost your organization to implement and operate the system itself. That sounds simple, but often times it isn't.
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How does a managed SD-WAN service work?
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