Method of Increasing Data Transmission Stability in Software Defined Network Considering Metrics of Quality of Service

This article presents a description of the method of increasing the stability of data transmission in a software-defined network (SDN) by means of its dynamic reconfiguration, considering the parameters of the quality of service (QoS) of communication channels and the reliability of nodes. The existing algorithms do not provide a comprehensive solution to the problem of determining the most optimal path that would provide a connection from the source point to the destination. They consider only certain parameters of the network, depending on which the time spent on communication between nodes is less than in the case of other routes. In conditions of growth in the number of users of computer networks and the number of node switches, there is an urgent problem of increasing the stability of data transmission in branched computer networks. It is proposed to solve this by considering the quality of service parameters of communication channels when constructing routes. The aim of the research is to increase data transmission stability in a virtual software-defined network in conditions of failures of nodes and increasing loads on communication channels. The first objective of the research is to create a method for finding a set of non-intersecting optimal paths that would consider various metrics of the quality of service of communication channels. The second research objective is to develop a dynamic reconfiguration mechanism for SDN switch flow tables to be able to reroute traffic in the event of individual node failure. In the course of the research, the first objective was performed by mathematically substantiating the construction of the generalized weight matrix of transitions between the nodes of the network graph. When creating a request to determine a route for traffic in the network, its status and indicators are updated in order to increase the accuracy of data on available resources and establish the optimal path that meets the quality of service criteria. It is proposed to consider four quality of service metrics for path construction: the number of hops between vertices, the available bandwidth, the time delay, and the percentage of lost packets. Using the generalized transition weight matrix, the SDN controller selects the most optimal path among a set of alternative non-intersecting paths. Then, using the reliability coefficients of the nodes as a constraint to choose the optimal path between the vertices, the controller chooses the main route from the set of alternatives according to the requirement for the reliability of the nodes set by the administrator, and considers the other routes as backup. The second task was solved by proposing a method of dynamic network reconfiguration using known paths. If in the process of traffic transmission there is a failure in the intermediate links of the network or the communication channels between them, then monitoring data of the SDN controller are used for reconfiguration and bypassing the problem area, which allows the controller to quickly choose an alternative path for sending traffic and build a new path based on already known data about communication channels in the network. The obtained results of theoretical studies testify to the correctness of the chosen solutions and proposals for the objectives set in the article.