Software-defined networking

Software-defined networking (SDN) is an approach to computer networking that allows network administrators to programmatically initialize, control, change, and manage network behavior dynamically via open interfaces and abstraction of lower-level functionality. SDN is meant to address the fact that the static architecture of traditional networks doesn't support the dynamic, scalable computing and storage needs of more modern computing environments such as data centers. This is done by decoupling or disassociating the system that makes decisions about where traffic is sent (the SDN controller, or control plane) from the underlying systems that forward traffic to the selected destination (the data plane).

SDN was commonly associated with the OpenFlow protocol (for remote communication with network plane elements for the purpose of determining the path of network packets across network switches) since the latter's emergence in 2011. Since 2012, however, many companies have moved away from OpenFlow, and have embraced different techniques. These include Cisco Systems' Open Network Environment and Nicira's network virtualization platform.

SD-WAN applies similar technology to a wide area network (WAN).

The origins of software-defined networking began shortly after Sun Microsystems released Java in 1995.

One of the first SDN projects was AT&T's GeoPlex.AT&T Labs Geoplex project members Michah Lerner, George Vanecek, Nino Vidovic, and Dado Vrsalovic leveraged the network APIs and dynamic aspects of the Java language as a means to implement middleware networks. "GeoPlex is not an operating system, nor does it attempt to compete with one. It is networking middleware that uses one or more operating systems running on computers, connected to the Internet. GeoPlex is a service platform that manages networks and on-line services. GeoPlex maps all of the IP network activities into one or more services."

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