Research And Implementation On Flow Rule Management Technology In SDN

The SDN network realizes the decoupling between the forwarding plane and the control plane,and the controller can implement fine-grained forwarding control on the flow by issuing flow rules containing more matching fields.More matching fields make the flow rules require more storage space,while the size of the TCAM in the hardware switch is limited,and the capacity of the flow table is limited.When the flow table is full,to implement the forwarding of the flow,the switch will repeatedly swap in and out of the flow rules,which will greatly increase the load of controller.Therefore,it is of great significance to manage the flow rules in the switch's flow table and achieve efficient utilization of flow table space.The flow rule management of SDN includes the generation,installation and deletion of flow rules.This paper focuses on the management of timeout and deletion of flow rules,manages the life cycle of flow rules under normal circumstances and the deletion of flow rules when the flow table is full.The flow rule management technology based on flow characteristics is proposed,and the flow rule management system for SDN networks is designed and implemented.The main contents and contributions of the paper are as follows:For the flow rule timeout management problem,this paper statistics and analysis of the time and length characteristics of the flows,studies the influencing factors of flow rule timeout,and proposes a flow rule timeout management technology based on the time characteristics of flow packets.Through the simulation experiment,it is proved that the technology can effectively reduce the flow table occupation of the switch,reduce the number of flow rules generated by the controller,and the impact of the flow rule hit ratio is also small.Aiming at the problem of flow rule deletion management,this paper analyzes the affecting factors of the flow rule deletion priority when the flow table is full,preferentially deletes the flow rules with small number of packets per second.Then,this paper proposes a flow rule deletion management technology based on the packet number per second of flow.The simulation results show that this technique can effectively improve the hit ratio of the switch flow rules under the condition of limited flow table size.Based on the proposed flow rule management technology,a flow rule management system of SDN network is designed and implemented,which manages the generation,installation,deletion and information statistics of flow rules.By replaying the real network traffic,this paper tests and analyzes the system.The results show that,under the condition of limited flow table size,the system can effectively reduce the flow table occupancy,improve the hit ratio of flow rules,and reduce the number of flow rules generated by the controller compared with the solution in ONOS and"intelligent timeout master",which has a better effect.