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Comparing Apples And Oranges.

Apr 22, 2015

Executive Director Dan Pitt discusses three developments in networking, including their pros and cons.

In my latest contributed column for InformationWeek, I attempt to resolve some of the confusion around three recent developments in networking (OpenFlow, VXLAN, and Cisco ACI). Below is an excerpt from that piece, offering an overview of OpenFlow, and the full article can be found here.

Efforts to virtualize the network are only a few years old and a number of approaches have emerged, leading to an explosion of terms and acronyms — and understandable confusion. Three terms relating to network virtualization are getting the most attention: OpenFlow, Virtual eXtensible LAN (VXLAN), and Cisco Application Centric Infrastructure (ACI). While it may seem like comparing apples and oranges, examining the pros and cons of these three approaches is key to understanding the evolving network virtualization market.


OpenFlow® is a communications protocol, and foundational element of the software-defined networking (SDN) architecture, which decouples network control and forwarding functions. SDN centralizes network intelligence — and control — in software-based controllers that maintain a global view of the network. Currently, OpenFlow® is the only open standards-based “southbound” protocol for communicating between an SDN controller and network equipment. It allows for the direct programming of network hardware such as switches and routers, both physical and virtual, making networks more dynamic, manageable, cost-effective and adaptable.

A key characteristic of OpenFlow® is that it uses flows to identify network traffic, based on pre-defined match rules that can be statically or dynamically programmed using the SDN control software. In the simplest of terms, OpenFlow® conveys forwarding information from a controller to a collection of switches, telling the switches what to do. In return, the switches provide counters and other data to the controller.

Because it operates on flows, OpenFlow® provides IT with extremely granular control, enabling the network to respond to real-time changes at the application, user and session levels. OpenFlow® allows IT to define how traffic should flow through network devices based on parameters such as usage patterns, application needs, service-level agreements and cloud resources.

For descriptions of VXLAN and Cisco ACI, as well as an overview of their pros and cons, please read “Understanding OpenFlow, VXLAN and Cisco’s ACI.”

– Dan Pitt, Executive Director