OpenFlow is a widely used protocol for software defined networks (SDNs) that presents a new paradigm in which the control plane is abstracted from the forwarding plane for the network devices. This approach differs from the conventional networking architecture, where both planes reside on the same networking device. In SDN approach centralized entities called “controllers” act like network operating systems run different applications that manage and control the network via well-defined APIs. OpenFlow switch is the forwarding plane in SDN architecture that has tables of packet-handling rules. Traffics passing the switch are compared against these rules and a match – action method is applied to the traffics. Depending on the rules installed by a controller application, an OpenFlow switch can act like a router, a switch, or a middle box without much caring about what kind of vendor to use in the network.

Data centers’ networking is one of the applications that showed successful integration with OpenFlow protocol by making the network more consistent to the rapidly expanding number of virtual machines. But with the growing traffic in the data centers, the need for high controllers’ performance increases. Therefore, in this thesis we presented a performance evaluation in both throughput and latency perspectives for the current well-known OpenFlow controllers: NOX, Beacon, Floodlight, Maestro, OpenMul, and OpenIRIS. Controller benchmarking tool was implemented for incremental number of switches connected to the controller under test, and the results show that the OpenMul controller has the highest throughput, while OpenIRIS controller shows the lowest latency.