White box switches refer to the ability to use ‘generic,’ off-the-shelf switching (or white box switching) and routing hardware, in the forwarding plane of a software-defined network (SDN) which makes them SDN switches. White box switches are really just that – ‘blank’ standard hardware. They represent the foundational element of the commodity networking ecosystem required to enable organizations to pick and choose the elements they need to realize their SDN objectives.
White box switches rely on an operating system (OS), which may come already installed or can be purchased from a software vendor and loaded separately, to integrate with the deploying organization’s Layer 2/Layer 3 topology and support a set of basic networking features. A common operating system for SDN switches, like, white box switches is Linux-based because of the many open and free Linux tools available that help administrators customize the devices to their needs. Traditional switches and routers generate and maintain their own forwarding and routing tables that can, generally speaking, broadcast to neighboring switches and routers. A white box switch may come pre-loaded with minimal software or it may be sold as a bare metal device. The advantage of this approach is that switches can be customized to meet an organization’s specific business and networking needs
White Box Switching in SDN Environments
Within an SDN environment, the apps running on top of the SDN Controller are what provide the higher level orchestration and programmability of the network. The SDN Controller uses OpenFlow (or another southbound API) to program the forwarding table of the white box switches and dictates how to route connections to accomplish the appropriate tasks for the applications. Because they are so flexible, white box switches an also be used to support a range of open source management tools, including OpenStack, Puppet, and Chef which is a feature of most SDN switches.
Some industry onlookers have questioned the market potential of white box switching, noting they are likely attractive to organizations who are looking to extract value out of their infrastructure and drive revenues, versus those who are running the network as a tool and IT expense. Examples of vendors offering white box switches include Accton, Celestica, and Quanta Computer.