Vendors take alternatives to OpenFlow SDN

Last updated:June 2015

Editor's note

For a while, the terms OpenFlow and software-defined networking (SDN) were nearly interchangeable. The networking protocol enjoyed a lot of early hype, and network engineers saw it as the answer to SDN. But that attitude is changing, led in large part by networking vendors' efforts to differentiate their own SDN offerings -- and to maintain their market share. This guide provides an overview of opinions and approaches to OpenFlow SDN and how vendors are responding to the SDN protocol.

1SDN is about network programmability, not necessarily OpenFlow

However, an OpenFlow network requires an OpenFlow controller and a network-switch vendor that supports the protocol. And some networking vendors are hesitant to jump on the bandwagon. Companies such as Cisco, VMware, Juniper, Brocade, Avaya, Embrane, Plexxi and PlumGrid posit that SDN is about network programmability, not necessarily OpenFlow.

It's worth noting that many of these companies are actively involved in the development of OpenFlow through the Open Networking Research Center and the Open Networking Foundation. So while each they want to promote and maintain their own approaches to SDN to differentiate their products, they're also keeping OpenFlow SDN in the mix.

2Making OpenFlow SDN work on top of traditional hardware

Other SDN companies, like Big Switch Networks and HP, are making OpenFlow function on top of legacy hardware. The latter's Virtual Cloud Networking software functions is enhancement to OpenStack Neutron, as well as an SDN application that can run on HP's OpenFlow controller. HP has also integrated its controller and network management platform with VMware NSX, for joint management across physical and virtual networks.

Big Switch Networks is a big OpenFlow proponent, but the company also aims to make it possible for enterprises to build SDNs on top of any underlying physical infrastructure, whether or not they're OpenFlow-friendly. In doing so, Big Switch hopes to enable network virtualization that will easily rival VMware. Big Switch offers an OpenFlow controller, and it enables an OpenFlow network overlay technology as part of its Big Virtual Switch network virtualization application.

3The future of OpenFlow

Despite some networking vendors' efforts to shift focus away from OpenFlow, the protocol continues to have passionate advocates among the networking community.

As vendors develop their own approaches to SDN in response to OpenFlow, the protocol continues to evolve and its capabilities continue to expand. With the "southbound" functionality of OpenFlow established, the Open Networking Foundation (ONF) is focusing on the protocol's "northbound" functionality.

In August 2012, the ONF acknowledged that developers of network-control applications wish to write "for the northbound edge of an OpenFlow controller." It also announced an initiative to catalog and characterize existing APIs in a first step toward assessing market requirements.