Analyze OSPF Convergence Time in the Presence of Single and Multiple Failures
Cristina-Loredana Duta, Laura Gheorghe, Nicolae Ţăpuş · 2015
Open Shortest Path First (OSPF) is a widely used link-state routing protocol in IP networks. Processing delays in OSPF implementations have an effect on the time necessary for inter-domain and intra-domain routing to re-converge after a topology change. OSPF implements different timers in order to reduce the protocol overhead. These timers ensure that the OSPF network takes several tens of seconds to recover from a failure. The delay that appears in the convergence time is due to failure detection, more specifically, is due to the value of timers and of routing calculation scheduling. In this paper, we evaluate OSPF convergence time in the presence of single or multiple failures using Quagga software routing engine and Mininet simulated network environment. The purpose is to understand the impact of failures on convergence, to observe their effects on end-to-end traffic and to determine what components should be taken into consideration in order to reduce the convergence time in a network topology based on OSPF.