Dissertation (MSc Information Technology)This research investigated the impact of network topologies on the performance of OpenFlow protocol. OpenFlow Protocol is a southbound protocol over Secure Socket Layer (SSL) in Software Defined Networking (SDN). SDN architecture separates the intelligence (decision making) part (control plane) of network devices from forwarding capability (data plane). OpenFlow protocol is the communication protocol for exchanging control messages between control plane and data plane. The research investigation was based on the performance of OpenFlow protocol version 1 on four topologies; unconnected switches, linear, tree, and typical DCN. POX software was used as controller in control plane. The motivation behind the study is based on the fact that topology in SDN is discovered by exchanging lldp based control messages. Despite the impact of lldp based control messages on the performance of SDN, to the knowledge of this study the impact of network topologies on the performance of OpenFlow protocol is yet to be explored. The research adopted mininet emulation tool to simulate four topologies. The performance of OpenFlow protocol was measured in terms of throughput and delay. This data was observed through wireshark. Descriptive statistical analysis of data was done through Wireshark and Microsoft excel 2010. It was found that the throughput of OpenFlow protocol in terms of packet per second (pps) is highest in typical DCN and lowest in unconnected switches. OpenFlow protocol in typical DCN topology transfers higher number of information with lower delay than any other topologies simulated in this environment.