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Four steps to prepare for an SD-WAN deployment

SD-WAN touts promising benefits. But if you're considering SD-WAN deployment, take time to prioritize remote sites, and crunch the numbers to make sure it's right for your company.

Software-defined WAN technologies are being proudly marketed as an end-all, be-all solution to eliminate costly MPLS and Metro Ethernet connections in favor of low-cost broadband. In many cases, this claim is true. Some circumstances, however, dictate the need to maintain some or all leased-line connectivity. Let's look at several of the connectivity decision points you should consider as you begin your preparation for an SD-WAN deployment.

It's important to understand SD-WAN technologies are already quite capable. Compared with standard WAN acceleration techniques that simply cache, compress and otherwise optimize a link to lower overall bandwidth, SD-WAN also helps lower overall latency. When two or more WAN links are available, SD-WAN tools monitor each link to determine the fastest path at any given moment. Data is forwarded down the best path on a packet-by-packet basis. Ultimately, this helps reduce overall delay and jitter -- even when using standard internet broadband connections. All of these reasons explain why high growth is expected in this technology segment.

Yet, while SD-WAN works, it may not be able to fully handle everything you throw at it. If your WAN currently consists of leased lines -- whether they are MPLS, Metro Ethernet or legacy digital lines -- the service provider can provide end-to-end throughput and latency guarantees. These are included in your service-level agreement when you sign the contract. And while SD-WAN over multiple broadband connections certainly helps with throughput and latency issues, there is still no performance guarantee for the customer. If you are running SD-WAN across two separate broadband connections, for example, yet both are experiencing internet congestion or high latency to the destination, your end users are going to notice. This is especially true with latency-sensitive data flows, such as real-time voice and video communications.

Growth of SD-WAN expected to accelerate
SD-WAN deployments are projected to skyrocket in the next few years, with 30% of enterprises using the technology by 2019, compared to only a handful today, according to Gartner.

Preparing for SD-WAN deployment

Here are four actions you should take to help your organization decide if SD-WAN is a good idea, and where.

1. Prioritize remote sites. A first step in any SD-WAN migration plan is to prioritize your remote sites by how critical they are. If a site is considered critical to the organization, it may make sense to maintain your leased-line infrastructure to better ensure operational effectiveness around the clock. You can, however, consider a substitute connection by implementing SD-WAN and adding a broadband link as a secondary connection. This will give you intelligent routing capabilities over a less-expensive transport medium. In other words, you can replace a more expensive secondary leased line with a cheaper broadband connection.

So, if a company previously had two MPLS links connecting a single WAN site for redundancy purposes at critical locations, you could eliminate one MPLS link, replace it with a cheaper broadband internet link, and implement intelligent SD-WAN routing to route across one MPLS and one broadband link. You may even be able to lower the overall leased-line throughput to a critical site to save money, while still providing the necessary level of service demanded.

2. Research broadband options. If a remote site is on the lower end of your criticality list, by all means, consider replacing those leased lines with SD-WAN and two or more low-cost broadband links. Just keep in mind that broadband options are going to vary widely from remote site to remote site. You may even run into situations where multiple carriers do not exist. That's why a thorough investigation of broadband and leased-line options is necessary before making any final decisions on an SD-WAN deployment.

3. Migrate sites incrementally. You should also migrate remote sites to SD-WAN on a rolling basis. Start with just a few low-priority locations to test SD-WAN capabilities and to work out any configuration kinks along the way. Many SD-WAN technologies are being advertised as plug-and-play. But in every situation, SD-WAN deployment will require configuration adjustments to better optimize the WAN for your specific application and data transport needs.

4. Crunch the numbers. Finally, once you've investigated which remote sites can eliminate or downgrade expensive leased-line connectivity -- and once you figure out broadband options -- it's time to crunch the numbers. Because SD-WAN technologies are relatively new, vendors are asking a premium price. As a result, the cost reduction of overall leased-line replacement with broadband must cover the cost of purchasing SD-WAN hardware, software and services over a relatively short time frame. You should aim for a break-even point of three years or less. If you can't reach that goal, you may want to wait until the cost of SD-WAN deployment drops.

Next Steps

What to consider before adopting SD-WAN

Getting started with SD-WAN technology

How to estimate SD-WAN return on investment

This was last published in February 2017

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