Research And Improvement Of BGP Route Flap Dampening Algorithm

With the rapid expansion of the size of the network, the requirement of the network's performance has been increased. In order to facilitate the management of the network, Internet is divided into many autonomous systems and Internet transfer routing information using border gateway protocol. Routing system is the core component of Internet, and it keeps the control of network IP traffic. The instability of routing system is the key point to induce poor network performance. As we know, route flap is one of the important reasons of routing instability, if route flaps frequently, it can not only increase the router's CPU processing and the consumption of network bandwidth, but also cause network being paralytic on serious cases. Therefore the research on how to damp the route flap effectively and locate the routing flap source has great significance, and it is also the main research direction of upgrading the network stability.The essential of route flap algorithm is forecast the stability of the route, and damps the instability routes to prevent them to be spread in the entire network. As the route flap mechanism plays an important role in the Internet routing stability, it is necessary to design a more efficient algorithm. At the same time, locating route flap source provides the possibility for resolving the root cause of BGP routing instability. So this paper takes the goal of enhancing the performance of RFD algorithm and locating the flap source. We studied the algorithm deeply. The main work is described as follows:(1)We noted that RCN route flap damping algorithm produces a lot of updates because of invalid path exploration, so we propose a Route Cause Notification RFD algorithm with path exploration detecting using the RCN table and the characteristics of routes generated in path exploration. The algorithm can distinguish route flap and path exploration correctly and damp the invalid routes. Simulation results indicate that the algorithm guarantee the rapid convergence of the network and reduce the number of updates significantly, so it improves the performance of the RFD. And then we get a better performance algorithm combined with RCN route flap algorithm.(2) We studies two main reasons which cause route flap, and they are router fault and link failure. We propose a LRCN algorithm for locating routing flap source using the value of link-value and the RCN table. Simulation results indicate that the algorithm can locate the flap source correctly, so it provides the possibility for eliminating the route flap and has contributed to the Internet routing stability.(3) For the performance indicators of the algorithm: convergence time and the number of updates, we did a large number of experiments to analysis the influence of MRAI,SSLD,WRATE,routing policy and network topology on the performance of RFD algorithm. We summed up that using the SSLD mechanism and routing policy in the network can play a more efficient on route flap damping algorithm.