Abstract Stability Issues in OSPF Routing

We study the stability of the OSPF protocol under steady state and perturbed conditions. We look at three indicators of stability, namely, (a) network convergence times, (b) routing load on processors, and (c) the number of route flaps. We study these statistics under three different scenarios: (a) on networks that deploy OSPF with TE extensions, (b) on networks that use subsecond HELLO timers, and (c) on networks that use alternative strategies for refreshing link-state information. Our results are based on a very detailed simulation of a real ISP network with 292 nodes and 765 links. 1