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Software-defined networking, or SDN, is a strategy that splits the control plane from the forwarding plane and pushes management and configuration to centralized consoles.
SDN is now over 10 years old. When the history of SDN began, many people thought gleaming software-defined networks would replace tightly coupled, vertically integrated network products. The massive data centers of Amazon, Facebook and Google all moved to SDN, but why isn't SDN everywhere?
Well, it is, even if it's not always called SDN.
The principles of SDN are alive and well, thanks, in part, to cloud computing. All of today's major cloud providers use SDN. As more workloads move to cloud environments, more organizations will use SDN. Let's look at the evolution of SDN to see how it got to this point.
The role of vendors in the evolution of SDN
In the corporate data center, practically everything is virtualized -- from workloads to servers to networking. VMware, the king of the virtualized data center, bought Nicira and rebranded its SDN-style networking as VMware NSX. Hundreds of thousands of virtual machines in data centers around the world run on NSX, which means they run on SDN.
Cisco -- the company that initially scoffed at SDN, because it threatened the status quo -- eventually hopped on the bandwagon and introduced an SDN variant, Cisco Application Centric Infrastructure, to the market, trying to embrace the future without letting go of the past.
Other networking companies began to turn to SDN, as well. Juniper Networks embraced SDN in its Contrail products, and Arista Networks integrated SDN principles into its Extensible Operating System in an attempt to bring a new software-defined cloud networking to the market.
Smaller vendors, like Dell Technologies and Hewlett Packard Enterprise, used the SDN strategy to open up their platforms, split tightly coupled hardware and software apart, and inject customer choice into the process. While not necessarily SDN, this open networking strategy is an important part of the evolution of SDN's overall viability.
As networks become more diverse and new workloads move to the edge, it is only fitting that SDN finds a place in these new, complex environments. Even in the consumer world, elements of SDN make their way into products. For example, I run a controller-based network system in my home and home office.
Where is SDN now?
To answer the question of what became of SDN: In reality, SDN is here today. But you won't often see products with a big SDN tag on them. Instead, SDN sits inside them, enabling those products to do more than their proprietary vertical predecessors ever could.
I used to say, "If we believed everything analysts told us, we'd all run Itanium blades," which drew laughs until I said the analysts were right. At the time, Itanium was the only mainstream 64-bit hardware, and blades were the only real, dense form factor. In a 1999 lexicon, the only way to describe the future's dense 64-bit platforms was to call them Itanium blades. Analysts weren't wrong, but conventional norms limited them.
This is the same way analysts in the past viewed a future SDN-driven world. That world is here and integrated into tools we use today -- it's just not called SDN.
Gartner's 2019 Hype Cycle declared SDN deceased