Research On Software-defined Wireless Mesh Network Routing Based On Openflow

Wireless mesh network is a multi-hop transmission,self-healing,and self-organizing network,and it is difficult to select the optimal path based on the global topology of the network,because it uses distributed protocols for networking.Software-defined network uses a centralized architecture,and its controller has global information about the network,which facilitates unified management and scheduling of the network.Introducing the software-defined network architecture into the wireless mesh network can help to solve the problems of traditional distributed routing protocols that are difficult to find the optimal path and frequently disconnected of the path.At present,the OFDP protocol is mostly used in software-defined networks to complete topology discovery.This protocol does not take into account the unstable and small bandwidth characteristics of wireless communication,and generates a large number of control messages.First of all,this paper chooses the OpenFlow protocol as the southbound protocol,and improves the AODV protocol,so that the node actively selects a stable neighbor node,collects the link state,and sends it to the controller.This method can effectively reduce the number of control messages generated by topology discovery,and ensures that the network topology obtained by the controller is real-time and stable.At the same time,the controller calculates the optimal route for single and multiple data streams according to the current network topology and link state information,so as to realize the flexible transmission of data streams and achieve the purpose of network load balancing.Secondly,in order to solve the problems of insufficient performance of a single controller,high control plane delay and low network robustness,this paper studies the multi-controller solution based on software-defined wireless mesh network.Regarding the problem of how the switches select the controller and the coordination between the controllers,this paper proposes the principle that the switches select the optimal controller according to the smallest number of hops and closest distance,the method that controllers establish channels to exchange topology information to obtain the entire network topology.This solution avoids the problem that the centralized control solution cannot work after the controller is down in the single-controller solution.Finally,this paper chooses the simulation software Mininet-WIFI and the controller Ryu to build a simulation platform,which verifies the feasibility of the schemes proposed in this paper,and compares it with other schemes to illustrate the effectiveness of the scheme in this paper.The simulation results show that the routing algorithm proposed in this paper has optimized the end-to-end delay,link bandwidth and packet loss rate.The multi-controller solution can reduce the delay of the flow table issuance and the end-to-end delay of the network.