How does software-defined networking differ from virtual networking?

The architecture of a software-defined network (SDN) is designed with a separation between the control plane and the data plane (user plane). What this means is that the processing of network functions takes place somewhere other than the physical devices that are carrying the data packets to far-flung parts of the world. Centrally-managed SDN controllers dictate traffic flows and allow for agile and flexible management of the network.

The SDN architecture has three layers:

• Application layer
• Control layer
• Infrastructure layer

SDN is being strongly promoted by the Open Networking Foundation. The idea is to replace proprietary network equipment with off-the-shelf, white box switches. Linux-based servers can be configured with software to create virtual environments.

Virtual networking, on the other hand, may refer to a number of implementations. The traditional idea of a virtual network has been one that connects wide area network components using virtual links, such as VCs, VLANs or VPNs. In today’s evolving IT infrastructures, other developments lean toward different descriptions for the term. Some vendors have created virtual services switches or platforms that consolidate diverse services and functions. The aim is to simplify network infrastructure through virtualization. One of the key aspects of virtual networking is the disaggregation of software and hardware.

Overlay virtualization is a solution that is becoming more common. A form of virtual networking, topographies with no links to physical devices allow for private connections between isolated network segments. The flexibility of overlay networks makes it possible to run a variety of network traffic among virtual components in cloud computing environments. Not only virtual machines comprise this architecture, but virtualized switches, routers, firewalls, load balancers and other network appliances are possible through network functions virtualization (NFV).