Study On Flow Table Usage-aware QoS Routing Mechanism In Software Defined VANET

VANET can provide a wide range of security and non-security related services.However,the existing VANET is difficult to guarantee the QoS of these application services.Many researchers proposed that the architecture of software defined network should be introduced into the VANET,which can separate the VANET data plane and control plane,realize the systematic and flexible control of the network,and make it programmable.However,the QoS requirements of different application services are also different under the software defined VANET architecture.So it is worth exploring how to protect the application of the software defined VANET QoS.In order to provide QoS guarantee for application service,many researchers have conducted theoretical and practical research,but most of the existing studies were facing the problems of single-function service with poor concurrency,lack of dynamic service access and exit and having no the ability to perceive amount of flow table.To solving the aforementioned problems,the main work of this paper is as follows:Firstly,experiment was conducted to analyze the influence of flow table overflow on SDN controller and QoS routing mechanism.Since the implementation of SDN routing process has to rely on the management of the flow table of the switch,the impact of the flow table policy on the performance of QoS routing mechanism is important.The OpenFlow network flow table overflow phenomenon and reasons were analyzed,and then it was verified by experiments that the flow table overflow mechanism had important influence performance on SDN controller and QoS routing mechanism.In order to avoid the flow of QoS routing table overflow adverse effect,a flow table usage-aware QoS routing mechanism was established,which can the perceive the change of the state of the routing table.The experimental results showed that the mechanism can sense the overflow of the table overflow,reduce the load of the controller,and protect the application service QoS effectively.Secondly,VANET architecture defined by heterogeneous multi access software was designed and a dynamic QoS support framework based on the perception of flow table was proposed,which allowed us to manage the network in a modular way and supported the dynamic entering and exiting of the service flows.On this basis,a flow table usage-aware QoS routing model was established with multi-service flows and multi-constraints,which considered not only the parameters of link state such as packet loss,delay and throughput,but also the service requirements and the flow table usage,providing concurrent dynamic QoS routing for VANET application service.Experiments showed that QoS routing mechanism proposed in this paper can not only meet the service requirements of their packet loss,latency and throughput,but also was capable of perceiving the usage of flow table so as to avoid the influence of flow table overflow for QoS routing mechanism,which can further improve the performance of network QoS.