Switching to SD-WAN Doesn’t Mean Ripping Out Your MPLS Network
by January 2, 2018

Filed under: Networking Technology, Performance Monitoring

SD-WAN was originally designed to be the successor technology to MPLS networks, but it doesn’t appear to have worked out that way. Research from Nemertes has shown that nearly 80% of companies with a pre-existing MPLS deployment retain the technology after SD-WAN adoption. Clearly there is some synergy between SD-WAN and MPLS. How does an older technology co-exist with a newer one that’s designed to replace it? Here are a few reasons why SD-WAN hasn’t entirely replaced MPLS.

MPLS Provides Benefits After a Large Upfront Cost

One reason to keep MPLS, assuming you had one to begin with, is because the equipment and the installation of an MPLS was probably expensive to begin with – both in terms of time and money. MPLS requires a specialized router to create the preset Label Switched Paths that provide advantages in both speed and traffic shaping. After an initial large investment in equipment, enterprises find that MPLS pays for itself both in scalability and a reduced cost per bit versus carrier ethernet.

Scalability is all relative, of course. Putting in an MPLS gets you a reliable high-speed network, but the drawback is time. Implementing an MPLS network can take longer than six weeks, which is a huge drawback in a world of unpredictable customer demand and tight schedules. Provisioning anything other than very important static connections via MPLS requires careful planning.

SD-WAN is Faster and Cheaper, but Less Reliable

By contrast, SD-WAN is great for businesses that open up a lot of small branches, employ a lot of remote workers or frequently move from place to place. It’s also optimized for users undergoing a digital transformation, since it helps administrators efficiently pipe in SaaS applications. SD-WAN can be easily deployed via appliances or virtual machines, and runs perfectly well over consumer-grade internet.

This advantage is also a drawback, however. By exploiting the public internet, you’re also putting yourself at the mercy of the public internet’s failings. Every DDoS attack, every large-scale ransomware hack and every Amazon S3 outage is going to eat into your SLA.

Backing up MPLS with SD-WAN and Vice Versa

If you rely on MPLS and find yourself constantly scrambling to provision remote sites with WAN access, there’s an obvious and immediate solution—backfill with SD-WAN. MPLS takes too long to set up for remote or temporary sites, but SD-WAN is much more of a turnkey solution. It’s easy to set up SD-WAN quickly, so IT teams can use it as a temporary solution to cope with the lead time while they set up a more permanent MPLS implementation.

For less permanent or less important sites, administrators can make do with SD-WAN as a permanent solution. In this manner, SD-WAN lets administrators shave down MPLS costs, gives them more freedom of choice in network planning and allows them to pull in more SaaS services and hybrid cloud applications.

Better Still: MPLS, SD-WAN and Detailed Diagnostics

It can be a challenge to choose SD-WAN vs. MPLS, or some combination, for your particular business. What if you want to improve the performance of SD-WAN in a hybrid network scenario? What if you’re a newer company and you never used MPLS in the first place? In both scenarios, administrators find themselves working with a tool that lacks context for the applications running on top of it. SD-WAN may tell you that one connection is running faster than another, but it fails to give reasons why that may be—whether the problem is due to your network, the application itself or the ISP.

The right kind of modern monitoring can see into all networks, whether MPLS, SD-WAN, and others like WiFi and VNP, and rapidly diagnose problems. Monitoring a network before adopting SD-WAN also helps business IT teams find the root cause of network issues—and decide if SD-WAN is actually the solution. Administrators will receive network diagnostics both from the perspective of the network and from your users’ perspective, letting you validate your SLAs, monitor end-user experience, and even improve your public WiFi offering. For more on using AppNeta to improve the performance of SD-WAN, request a free trial today.