SD-WAN to SD-WAN Migration Guide

SD-WAN has now been in market long enough that customers are migrating from one SD-WAN topology to another, and we'll cover how to do that in this guide.

sd wan migration
Matt Pinto

May 31, 2023


SD WAN has come of age. Even though some businesses are preparing to transition from MPLS to SD-WAN or from other legacy solutions, SD-WAN has been around long enough that earlier adopters from the mid-2010s are now looking to upgrade their topology to a newer SD-WAN technology with a major network migration. 

Although SD-WAN is, by definition, flexible enough to accommodate changes in topology, modern innovations like SASE and SSE security features or SD-Branch are an incentive to merit a complete changeover.

What’s the best way to tackle a major SD-WAN to SD-WAN migration? We’re going to look at the pros, cons, and costing considerations of the three main strategies.

SD-WAN Conversion Method #1 – Staged Site-by-Site Approach

sd wan 1

In this approach, you’d cut over both your SD-WAN service as well as your circuit(s) at the same time on an individual site basis, or in small batches of sites. This approach makes sense if you’re migrating both your overlay (SD-WAN) as well as your underlay (internet / WAN circuits) because of a need to refresh circuit pricing, upgrade bandwidth, or separate your SD-WAN service from your ISP (shifting from Windstream’s SD-WAN product to Cato as an example). At each site you’d first activate your new circuit, activate your SD-WAN equipment, and then move site-level services over to the new SD-WAN / circuit when ready.


Low potential for double billing. Smaller sites are treated separately, which means shorter overall periods of duplicated billing.

Cutovers are small and quick. Site by site means individual cutovers are simpler and faster.

Problems are easier to solve. Each site has a primary point of responsibility, so troubleshooting procedures have fewer moving parts.


Greater overall admin burden. The addition of extra stages to the process causes more administrative hassles (but it’s still easier than conversion method #2).

Many, many cutovers creates additional administrative hassles.

Standardized tracking processes are needed to make sure the entire project runs smoothly, with consistent troubleshooting and update procedures followed at every site.

Partial disconnect orders are required for each site, once it’s cutover.

It’s a long haul. Even though each site cutover might run more quickly and smoothly this way, the overall migration takes longer using this method.

Cost considerations

You can expect 45 days of duplicated billing for the average enterprise network, averaged out across the sites.

You’ll also need to deploy Smart Hands Activation support.

SD WAN Conversion Method #2 – Turn Up New SD-WAN CPE Behind Existing Circuits

sd wan 2

You’d utilize this approach to migrate your SD-WAN overlay to a new service without a change in underlay (you already have adequate connectivity at the site). In this approach, you’d aim to run both SD-WAN services in parallel on the same circuits, either utilizing an extra circuit handoff or a switch, before turning down the old SD-WAN service. You’ll need to ensure you have adequate static IPs to run both services in parallel.


Lowest potential amount of double billing. As the ISP remains the same, there is greater continuity in the overall billing processes.

Fastest cutover. Due to the retained services of the ISP, the cutover processes are simpler.

Easily integrates new SD-WAN technology, without major business interruption.


Highest administrative burden, with multiple partners to include and with whom to communicate.

Each internet circuit requires a cutover event to switch over to the new SD-WAN provider.

Separate record updates and disconnection orders are needed for each circuit, once cutover.

Who owns the circuits? It becomes hard to tell during this kind of migration. There’s the original internet service provider.  Whoever ordered the circuits is responsible for opening tickets.  If the circuits were ordered by the business’ in-house IT department, then the business must open the ticket.

The new SD-WAN provider must perform any Layer 1 troubleshooting …but tickets must be opened by the business, who has to get in touch with the ISP. 

Even when the cutover is finished, you still have an additional third party here – the business will be the customer of record, with a Letter of Agency (LOA) authorizing the SD-WAN provider to manage the circuits.

And remember…you’ve got this kind of horseplay to contend with for every circuit.

Cost Considerations

The average enterprise network can expect 30 days of duplicated billing, along with the Smart Hands activation support.

SD WAN Conversion Method #3 – Single Event All-Sites Cutover to All-New Circuits and All-New SD WAN Network

sd wan 3

In this approach, you’d take the same approach as in Method #1, but do the cutovers at all sites at once, rather than one by one. 


Less administrative hassle. As one set of contracts ends, another begins. Less moving parts, much easier to transition.

Easier troubleshooting, more rigorous testing. The new network can be fully tested without any operational disruption. Troubleshooting responsibility rests with the new providers.

Simultaneous disconnect orders. Avoid the endless back and forth – you can submit all your disconnect orders in one go.


Most vulnerable to duplicate billing costs. You’ll need all the new circuits installed and functioning before the main event. Which means you’ll be paying for the first new circuit installed, right up until the last ones are installed – even if the first ones come in early.

Longest cutovers. All new circuits, all new providers – there’s a lot to transfer.

Longer project turnaround. It won’t take as long as a staged site-by-site, but it’s still going to be a longer and more involved process than applying new Customer Premises Equipment (CPE) to existing circuits.

Cost Considerations

You’re looking at a much larger duplicate bill – around 60 days for the average size enterprise network. By building a fully functional SD-WAN network in addition to your existing network, you’re also in line for around 60 days of duplicated SD-WAN costs. And, of course, you’ll need Smart Hands activation support.

If your enterprise has a severe case of network envy, and you have a clear use case for a next-gen, SD-WAN network, then Lightyear’s telecom procurement operating system should be your first stop. We’ll help you source exactly what you’re looking for, with industry experts on hand for personal consultation at every step.

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