Research On Quality Of Service Assurance Technology Based On SDN

With the rapid development of real-time media application such as video conferencing,voice over IP,The traditional network which uses best-effort strategy has been unable to meet the indicators of business such as delay,bandwidth and jitter.So the concept of QoS is introduced.While existing QoS systems implemented based on Int Serv or Diff Serv model have some shortcomings such as lack of automatic configuration,deployed at a high cost,lack of flexibility.To deal with these problems,the concept of SDN is proposed.Software Defined Network,regarded as a new kind of designed network architecture,is capable of realizing flexibly scheduling the network traffic and openly programming the network behaviors through decoupling the control plane and the data plate of network devices.SDN provides a new way to solve the QoS problem.This paper mainly uses the SDN network architecture to realize the quality of service assurance system based on SDN from the two levels of controller and switch.The system in the controller level achieves the network topology acquisition and update,network resource measurement,the best path selection and other functions,the best path selection algorithm integrates a number of QoS reference indexes such as hops,link delay and remaining bandwidth of the link so that the system can guarantee the QoS of the service at the global network level of the controller and can realize the Network load balancing;The system adds the port forwarding module at the switch level,realizes the traffic classification,queue management and queue scheduling function,so that the system can guarantee the QoS of all kinds of priority services at the switch level,and can prevent some Network congestion.First of all,this thesis introduces the basic concepts of QoS,and introduces the basic framework and working mechanism of SDN network,finally designs the service quality assurance system based on SDN based on these theories.The design and implementation of the system consists of two parts: Ryu controller's upper application system and Open v Switch port forwarding module.The Ryu upper application system consists of network topology module,delay detector module,network awareness module,network monitor module and shortest forwarding module.The core function of the five modules is the optimal path selection algorithm of the source node to the destination node.The algorithm guarantees the QoS of the service at the controller level.The Open v Switch port forwarding module mainly completes the service classification,queue management and queue scheduling function.Firstly,the packets are classified according to the To S field of the packet IP header.Then,the queue management is performed according to the Weighted Random Detection Algorithm(WRED).Finally,the scheduling algorithm WRR schedules the packets in the queue.The module achieves a differentiated treatment of the service flow at the switch level,and can guarantee the QoS of the high priority service more rationally.Finally,the simulation experiment was carried out in Mininet simulation network,the function of each module of the system is verified,which proves the function and superiority of the system in guaranteeing QoS.