Abstract
To ensure the quality of service (QoS) in computer networks is an important issue until now. Since the emergence of software defined networks (SDN) which decoupled the control plane and data plane has made networking management more flexible than ever before. In this thesis, we design and implement a QoS system based on the SDN architecture. We define a network wide class of services as well as data-rate limitation mechanisms through a given network of the switches and wireless access points. The users are classified as different classes according to their priorities. A bandwidth allocation algorithm is proposed to satisfy as many requests of users as possible. Experimental results show that our QoS system can guarantee a specific bandwidth for particular users to protect their bandwidth requests. We also integrate our QoS system with the virtual set-top boxes system to test the stability of our QoS system. The results show that we can dynamically adjust the bandwidth request of different classes of users to maintain the high quality of service for high priority users.