Research On Routing Technology Based On SDN Architecture In Wireless Mesh Network

Wireless Mesh network(WMN)has become an important research topic because of its easy deployment,self-organization,self-recovery and low cost.WMNs are complex in structure and often use interfaces between different vendors or even different products from the same vendor to configure individual network devices.WMN tightly couples control and forwarding planes,consists of Mesh routers with complex structures and functions,and runs a large number of distributed routing protocols.Network administrators cannot centrally schedule control and maintain the global network,so network routing efficiency and resource allocation capabilities are poor.IP-based wireless networks use hop-by-hop addressing to establish an optimal path to the destination node,which makes the path optimal only in a local range,not for the implementation of dynamic traffic algorithms.In addition,routing loops in wireless Mesh networks can also affect network performance.If the routing loops are caused by errors in the routing configuration of the host or router in the wireless Mesh network,or the routing protocol is trapped in a loop,it will seriously affect the overall performance of the network,such as occupying a large amount of bandwidth,losing data,excessive delay,etc.,and may even cause irreparable losses.To solve these routing problems,this paper introduces a software defined network(SDN)architecture,which uses controllers in a logical set to calculate routes and has the ability to precisely downstream tables.Therefore,the introduction of SDN technology to wireless Mesh networks can improve routing decisions and data resource allocation capabilities.In addition,due to the ring-free nature of SDN,it plays a significant role in the routing loop avoidance mechanism.The main work of this paper is as follows:1.A SDN-based shortest path optimization protocol(SDWMR)is proposed,which combines SDN with wireless Mesh network.The logically centralized SDN controller has a global network topology and is responsible for all control decisions in the network.First,the SDN controller establishes an initial path with the underlying Mesh node,and calculates the shortest path according to the route constraints,which is accomplished by the shortest path algorithm in the controller.Secondly,the controller transfers the calculated routing rules to the underlying Mesh nodes through the initial path.When large-scale traffic is transmitted in the shortest path,a shunt algorithm is used to solve the problems of path congestion and uneven resource allocation.The introduction of SDN technology solves the routing bottleneck for wireless Mesh networks,and improves resource management and routing efficiency.The routing protocol in this paper has been simulated using the Mininet-Wifi network simulation tool and compared with the two existing routing protocols.The simulation results show that the SDWMR routing protocol outperforms the existing OF-OLSR routing protocol and the Three-Stage routing protocol in terms of network throughput,latency and packet loss.2.A routing loop avoidance algorithm(RLAA)based on SDN architecture is presented,which combines software-defined networks with wireless Mesh networks using the same network architecture as the first innovation point.In wireless Mesh networks,routing loops resulted in loss of packets and large latencies,this is mean longer convergence times.Even in a non-circular SDN architecture,the problem of high priority of newly joined streams leads to routing loops.Compared with the traditional spanning tree protocol(STP),the RLAA algorithm is based on the non-loop feature of SDN network.It evaluates the route forwarding request initiated by a third party by auditing the flow tables related to the request and calculates the forwarding path of the data stream in advance by using the RLAA algorithm before changing the network forwarding rules.The loops are judged by analyzing the predicted simulated forwarding path to avoid routing loops.The scheme has been simulated by MininetWi Fi network simulation tool.The simulation results show that the routing loop avoidance algorithm in this paper is superior to Header-Tag,STP and other algorithms in terms of convergence time and control overhead.