| With the increase of network scale and the development of network technology such as virtualization,cloud computing and data center consolidation,enterprises and Internet users are demanding the performance,security and service quality of the network.The traditional Internet architecture could no longer meet the current service needs.The emergence of SDN architecture brings a revolutionary change to the traditional distributed network.It separates the control plane of the network device from the data plane,and uses the controller to control the network in a global view.It solves the problem that encountered in the traditional network fundamentally and broke through the bottleneck of network development,is the development direction of next generation network.The emergence of SDN brings new problems to network measurement and monitoring.Network administrators want to keep abreast of network performance and resource consumption in order to discover network bottlenecks,optimize network configuration,and discover potential risks in network.The basis of further load balancing,traffic engineering,intrusion detection and other management measures.However,many of the researchers proposed SDN environment monitoring program is difficult to achieve the balance between accuracy and overhead at the same time with real-time,so explore and study monitoring technology in SDN and design a more reasonable monitoring program is very necessary.Aiming at the problems faced by SDN network traffic monitoring,this paper proposes an intelligent monitoring scheme which combines active and passive way.On the one hand,using OpenFlow control messages(Packet-In and Flow-Removed messages)to monitor the shorter duration flows with zero overhead.By analyzing the flows,it can be seen that the flows with shorter duration accounts for a large proportion of all flows.Therefore,this method can save most of the monitoring overhead.On the other hand,the information of the flows with longer duration is obtained in real time by means of the active inquiry switch,and according to the changes of flows using linear prediction and fuzzy logic to adapt to adjust the time interval,which avoid over-inquiry or lack of inquiry.And developed the corresponding monitoring module on the Floodlight controller,then verified it with the Mininet simulation platform.Finally,it is proved that the scheme designed in this paper can accurately and realistically monitor the flows’ throughput and packet loss rate while reducing the monitoring overhead,and the two adaptive schemes can also adaptively adjust the query time interval according to the situation of the flows,so that the accuracy and overhead of long duration flows monitoring are optimized.And the advantages and disadvantages of the monitoring based on linear prediction and fuzzy logic are summarized by comparison and analysis.In summary,this paper has done a series of research and exploration on the SDN network monitoring.The experimental results show that the proposed scheme can collect information in real time and effectively,while taking into account the overhead of the system and reduce the load of the SDN controller.And provide new ideas and methods for network monitoring and management in SDN environment,has a very good practical significance. |
