Indiana University’s IT network is a showcase for OpenFlow-based SDN, and Matthew Davy,
chief network architect at the school, makes frequent presentations on IU’s project, including at an Open Networking Summit last fall at Stanford University. In February, HP announced that it would offer customers a free download of OpenFlow to deliver SDN capability across 16 product lines of HP networking hardware.
Also, networking startup Big Switch Networks introduced its first OpenFlow-based software controller, Floodlight, in January. Floodlight, written in Java, was released with an Apache open source license to encourage developers to write applications that deliver software-defined networking intelligence, said Isabelle Guis, VP of outbound marketing at Big Switch.
OpenFlow is a communication protocol that abstracts the data layer of a network in order to communicate, via an OpenFlow-enabled controller, with switches and routers on that network. On top of the controller is an application that issues commands to the network devices on how to operate. The point of software-defined networking is that the intelligence in the controller replaces--or, in some cases, complements--the intelligence in the network devices.
With OpenFlow, network administrators can control their network without having to go through the tedious and time-consuming task of manually reconfiguring network devices as on a traditional network, said Guis. "Network managers now can focus on contextual networks and defining rules in a software manner, making the business more agile but also integrating it better with the rest of the resources in compute and storage," she said.
However, there are already ways to automate networks without OpenFlow. A virtual LAN allows disparate network routers and switches to be operated as one network, no matter where the hardware is physically located. Devices on a VLAN can be configured through software. The Network Configuration Protocol (NETCONF) has been around for more than six years and is designed to provide a configuration interface to devices, said Ferro, who called it a "general-purpose open configuration protocol." In addition, he called Transparent Interconnection of Lots of Links (TRILL) an autonomous protocol that makes it possible for data to follow multiple paths on a network as needed.
But while those innovations automate networking in their own ways, OpenFlow is in a class by itself, he said. With OpenFlow, the software controller tracks the flow of data packets; notes their source and their destination, be it an IP address, a MAC address or a network port; and sends them on their way. "The rules say anything from this IP address to this IP address, let it happen, send it out on Port 3," Ferro explained. "What you’re effectively doing is going into the heart of the switch."
