Research And Implementation Of QoS Control Technology In SDN

With the rapid development of the Internet,the service types in the network are even increasing,it is different for demand for Quality of Service(QoS)in different types of services.However,traditional datagram network only provides a best-effort service.This makes it difficult to protect the different QoS requirements of different services in the case of congestion.The Software Defined Network(SDN),as a new type of network,decouples the control layer and forwarding layer in the traditional network,so that the control layer can obtain the whole network topology view,achieve centralized control of the forwarding layer behavior,and provide flexible QoS guarantee for the service data stream.It provides a new way for the research of QoS.This paper taking full advantages of SDN,which is programmable,easy to expand,and has strong network control capabilities,studies QoS control technology in the SDN.The main work are as follow: 1)Set different grade values on the four different types of services,propose a QoS control framework which distinguishes the service priority in the SDN,carries on the dynamic QoS route to the highest priority service and the shortest path algorithm route to the other level services at the expense of the hop;2)Use the QoS routing algorithm based on Lagrange Relaxation Based Aggregated Cost(LARAC)for the highest priority service at the cost of link congestion rate and hop count and in the condition of time delay constraint.3)Propose queue scheduling and managing strategy based on Priority Queue(PQ)scheduling algorithm,Deficit Weighted Round Robin(DWRR)queue scheduling algorithm and Weighted Random Early Detection(WRED)queue management algorithm,which can differentiate the scheduling management for different priority services.4)Improve Open Flow protocol to enable it to support queue control commands that can flexibly configure queue scheduling and managing strategy.In this paper,the topology-controling module,the network-monitoring module,the path calculation module,the routing management module,the queue agent module and the traffic management module of the QoS control framework are implemented respectively.In the real SDN,the function and performance of the QoS control framework are tested.The experimental results show that the QoS control framework can dynamically carry on QoS route to the highest priority service,which can guarantee the end-to-end time delay effectively and the QoS of different levels of service differentially and improve the throughput of network and the utilization of bandwith.