Improving network convergence time and network stability of an OSPF-routed IP network

The loss of routing protocol control messages due to network congestion can cause peer failures in routers, leading to routing failures and network instability. We attempt to decrease the network convergence time in response to a node or link failure in a network and study its implications on network stability. We develop an algorithm to dynamically tune OSPF failure threshold based on the network congestion level. The tunable OSPF protocol expedites failure detections as compared to standard OSPF protocol in lightly loaded networks by reducing the failure threshold parameter; whereas the failure threshold is increased during network congestion to sustain stable routing operation and avoid spurious failure decisions due to missed or delayed hello packets. Simulations performed with constant bit-rate (CBR) and FrP data traffic showed that the tunable OSPF protocol facilitated uninterrupted data transfer and resulted in shorter download times as compared to the standard OSPF protocol. Our findings demonstrate the importance of tunable failure threshold to achieve stable and robust network operation.