Software Defined Networks, Talha Ibn Aziz, Lecturer at the Department of CSE at IUT, introduces a new kind of network called ‘Software Defined Networks’ (SDNs). Aziz defines and explains what SDNs are and why specifically it is called a software defined network. SDN architecture divides the traditional protocol stack into two separate plans (sub-planes): a data plane and a control plane. A data plane consists of switches while the control plane consists of controllers. The data plane can only forward messages and cannot take any decisions like where to send the message and the control plane can take all the decisions. Aziz then shows an example of a traditional network compared to a software-defined network. Aziz then explains the process of converting traditional protocol stacks to the new SDN. Aziz walks through an example of conversion to SDN using an existing network in Australia called AARNET. The main motivations of SDNs are that the switches are simpler, the controller gets an overall view of the network, and the network can be configured and managed easily by the network administrator. Aziz concludes the lecture explaining the advantages and motivations of using SDNs as well as limitations and challenges of SDNs.