Research On SDN Network Delay Measurement Technology

With the continuous expansion of the network scale and the emergence of new technologies such as cloud computing and virtualization,which puts high standards on the performance of the network.Traditional network architecture seriously hinders the development of network innovation.The emergence of software-defined networking(SDN)adapts to the requirements of current network development and given the network more programmability,it separates the data plane and control plane of the traditional network,and the logically centralized control plane grasps the information of the entire network,which can realize flexible scheduling and programmable control of resources and support the rapid innovation of network services.Network users need a better user experience,so they have higher requirements on network performance.Network measurement also needs to change with the emergence of new SDN architectures,which poses a greater challenge for network measurement.In the aspect of network delay measurement,by measuring the link delay and path delay of the network,not only the network configuration can be optimized,but also data support can be provided for failure analysis.Therefore,it is necessary to explore the SDN network delay measurement technology and design a reasonable measurement method.The SDN network delay measurement in this paper is divided into link delay measurement and path delay measurement.Both of them need to make full use of OpenFlow protocol.For the delay measurement of the link,that is the delay between adjacent switches,the measurement result must be calculated to obtain,because the data obtained by the direct measurement is not the delay of the link,and it also includes the delay from the controller to the switch.For the measurement of the path delay,that is end-to-end delay,which consists of multiple links,the probe packet needs to pass through the switch on the path.This can be achieved by issuing the corresponding flow entry.The path delay calculation method is the same as the calculation of the link delay.Then,a corresponding measurement module is developed on the Floodlight controller,a virtual SDN network authentication measurement module constructed using Mininet.Experimental results show that the measurement results of path delay and link delay have small errors,high accuracy and meet the expected requirements.In addition,for the measurement of path delay,if the time delay of all paths is required,when the network is large,the direct measurement method will cause heavy measurement tasks.Because the number of links in the network will be less than the number of paths,so the solution is to use the information exchange between the controller and the switch to automatically measure all link delays in the network and obtain the path delay through indirect calculations.This method allows the controller to grasp the delay data of the links of the entire network,using Floyd algorithm can get the shortest path based on delay.Finally,the simulation of the experiment is carried out by Mininet.The experimental results show that this method has high accuracy and is sensitive to delay variation.The algorithm can achieve the purpose of path optimization.