How To Calculate Network Convergence Time In OSPF

I want to measure the the ospf convergence time on the given network topology (assume 5 nodes - partial mesh topology).I am using quagga software as routing software on linux box. Quagga is runnign fine and network is converged, able to see all the routes.. Quagga software is logging all the osfp information includign packets,state machines,etc.I am going to disconnect a link between node a to node b. and i want to measure the convergence time of the network.What is the network convergence time?My answer is, The time taken to reflect the topology change (link down/up, network condition change) to all the routers on the topology.Some routers(close by routers to the topology change) will get converged fast, and some routers(far away from the topology change) will have the higher convergence time. we have to take the highest convergence time of the router on the topology and we can says thats the ospf network convergence time.