Network convergence is the time that is needed for the network to respond to events. One of the significant factors in routing convergence is the detection of link or node failure (events). This is where BFD comes in to play. OSPF Timers The default OSPF LSA propagation timers are quite conservative. Lowering the values of the timers that control OSPF LSA generation can significantly improve OSPF convergence times https://www.ciscopress.com/articles/article.asp?p=1763921&seqNum=6