Why the Physical Network Still Matters in Software-Defined Networking

by Arthur Nichols
September 13, 2019

When the expressway ahead becomes gridlocked, do you accept the frustration of stop-and-go traffic? Or, do you take the next exit and dynamically navigate an alternate path to your desired destination? If you’re the latter kind of driver, you’ll want to keep reading.


Every day, more enterprise-critical infrastructure, applications and data live “in the cloud.” As users and operators shift attention to digital destinations, it’s tempting to ignore the physical paths that enable those connections. In a software-defined network, does the physical network still matter?

The path defines the experience

Like the roads between your home and office matter to you, the physical network that connects customers to the virtual world matters more than ever. In fact, the customer experience—for enterprise users and their customers—is directly impacted by the physical path that runs between users and the cloud-based content they need. Customer experience is largely defined by the performance of the primary network path, but it may be significantly impacted by the capabilities and expertise of the network service provider when the primary path suddenly becomes inaccessible.

When considering your wide-area network (WAN), it’s often the network segment closest to the customer that remains the weakest link in the chain. Delivering a superior experience, by getting “close to a customer,” is challenging when network capacity and/or performance management are inhibitors rather than enablers. Whether driving collaboration across a distributed workforce or securely processing e‑commerce transactions, reliable end-to-end connectivity is essential.

Beyond reliability, network performance becomes critical to ensuring a seamless end‑user experience—that’s true for internal customers relying on unified communications as a service (UCaaS) or enterprise resource planning systems and external customers streaming video, music and other latency-intolerant content. SD‑WAN can help alleviate some network shortcomings by routing traffic around the roadblocks, but ultimately the performance and reliability of the underlying physical network play an important role and will continue to matter.

Improving diversity with software-defined networking

When it comes to reliability, software-defined networking (SDN) is often combined with diverse infrastructure to automatically and instantly fail-over in response to an isolated outage or impairment within the core of a WAN. Having a provider that manages their own nationwide transport network to ensure optimal routing is a key aspect of delivering a great network experience.

When it comes to the last mile, it is often impractical and uneconomical for a single service provider to build out their own redundant facilities that connect to all the enterprise’s locations. For this vital component of the network, it is important to find a provider who has deep inter-connectivity with other providers with the ability to solve for the ‘last mile’ with the broadest set of options available (including its own metro fiber networks and on-net buildings including data centers that host cloud services). After all, the more options your routing software can leverage (be they fiber, copper, cable, cellular or fixed wireless), the less likely a circuit outage is to impact the user experience.

The impact of the network service provider

If your SD-WAN provider is relying only on public internet connections and only delivering an overlay for your WAN connectivity, they have no direct control over what happens when routing traffic that supports critical applications. Eliminating as many service provider hand-offs as possible greatly improves network manageability, performance, customer experience and cost. Ideally, one provider will meet all your connectivity needs and provide more modern ways to manage your network and applications via a “single pane of glass” that yields more efficient operations—whether you opt for a fully-managed solution or do-it-yourself.

Enterprises can benefit greatly from having end-to-end connections with a single network service provider. Like a seasoned cabbie in a city unfamiliar to you, leveraging the network of the right provider will get you where want to go, even when your usual route is blocked.