Network management and performance monitoring using Software Defined Networks Nowadays Computer Networks are in constant evolution. New methodologies and techniques are required to manage the network. Software Defined Network (SDN) is a new approach to manage and maintain the network infrastructure. Mininet is the most popular emulator to understand and experience how SDN works. Our proposed research addresses the following problems. i) Enhance default version of Mininet to create the custom topologies in a user friendly manner without explicitly writing any programs. The users/researchers can even specify the different link parameters like Bandwidth, Latency etc. through a simple text file and create the network topology of their choice to test their innovative ideas and protocols. ii) Our next focus is to collect the information from the SDN controller, preserve it for historical analysis and present via a web interface. iii) Use SDN to reduce the Layer-2 broadcast traffic in Data Centres. This is being achieved by making use of hierarchical switch connectivity with pseudo MAC addresses. iv) Our last focus is the introduction of Cross Layer Optimization algorithms for better resource utilization in Data Centres. These new techniques help the network administrator and the end user to experience better application and network performance.