Research And Implementation Of L7-based Routing In SDN

Quality of Service(QoS)routing can learn link performance in the network to select a route that meets quality requirements to transmit packets.As one of the means to ensure quality of service,it allocates network resources reason-ably and guarantees transmission requirements for multiple services with dif-ferent resource requirements.QoS routing in the Software Defined Networking(SDN)environment utilizes the centralized control of the controller to collect the network state and calculate the routing,which preserves the advantages of QoS routing and reduces the pressure of switching equipment.However,in the current research on using QoS routing to ensure service quality in SDN,the SDN controller cannot perceive the service requirements of packets with unclear service service categories.The SDN controller lacks an effective mea-surement method for the link packet loss rate,which makes it impossible to routing for end-to-end packet loss rate.The SDN controller cannot flexibly calculate routing schemes according to different service requirements of dif-ferent services.This paper proposes a routing scheme based on the content of the application layer of Open System Interconnection(OSI L7)of the packet to address the above problems.The main work and innovation of this paper are as follows.For packets lacking service types,this paper uses the regular feature rules established to match the byte sequence of the application layer to identify the application layer protocol of the packet and then determine the service category.If the regular feature cannot be identified,the port number is used to identify the application layer protocol.In the QoS routing of ensuring the end-to-end packet loss rate,this paper proposes a way to measure the link packet loss rate.It uses the specific field of the flow entry in the SDN switch to calculate the link packet loss rate at regu-lar intervals.The average value of the packet loss rate at several times in the past is used to estimate the actual link.The packet loss rate provides weights for the edges of the topology.This paper proposes a method to preprocess the link packet loss rate.On the premise that the monotonically increasing rela-tionship between packet loss rate and end-to-end packet loss rate remains is unchanged,the multiplicative metric attribute is transformed into an additive metric attribute to adapt to the search algorithm for multiple paths with smaller sum of weights.In terms of calculating routing,this paper divides the service categories into delay-sensitive and packet loss-sensitive.The link delay and preprocessed link packet loss rate are used as the weights of the edges of the topology to calculate multiple routes that meet the quality of service,and finally find the best route with the smallest end-to-end delay and end-to-end packet loss rate.This paper integrates the functions of identifying service types,measuring the link packet loss rate,and calculating routing into the Floodlight controller.Using Mininet to build a simulation network,we carried out functional tests and performance tests in this paper.The result of the functional tests show that the accuracy of identifying the service type in this paper is 98%,and the deviation of the measured link packet loss rate in this paper is controlled within 1%.Compared with the Floodlight routing scheme,the packet loss rate of the routing is greatly reduced,which proves our scheme in this paper can effectively improve the quality of service in SDN.The performance test results show that the average loss of the solution in this paper is about 1 millisecond,which is acceptable in the actual SDN environment.