As demonstrated through the examples in the preceding section, convergence is absolutely critical to a network's capability to respond to operational fluctuations. The key factor in convergence is communications among the routers in the network. Routing protocols are responsible for providing this function. Specifically, these protocols are designed to enable routers to share information about routes to the various destinations within the network.
One symptom of network instability that may arise is known as route flapping. Route flapping is just the rapid vacillation between two, or more, routes. Flapping happens during a topology change. All the routers in the network must converge on a consensus of the new ...