Achieving faster failure detection in OSPF networks

With the current default settings of the OSPF parameters, the network takes several tens of seconds before recovering from a failure. The main component in this delay is the time required to detect the failure using Hello protocol. Failure detection time can be speeded up by reducing the value of HelloInterval. However, too small a value of HelloInterval will result in an increased chance of network congestion causing loss of several consecutive Hellos, thus leading to false breakdown of adjacency between routers. Such false alarms not only disrupt network traffic by causing unnecessary routing changes but also increase the processing load on the routers which may potentially lead to routing instability. In this paper, we investigate the following question What is the optimal value for the HelloInterval that will lead to fast failure detection in the network while keeping the false alarm occurrence within acceptable limits? We examine the impact of both network congestion and the network topology on the optimal HelloInterval value. Additionally, we investigate the effectiveness of faster failure detection in achieving faster failure recovery in OSPF networks.