One of the most fascinating aspects of routing is a concept known as convergence. Quite simply, whenever a change occurs in a network's topology, or shape, all the routers in that network must develop a new understanding of what the network's topology is. This process is both collaborative and independent; the routers share information with each other, but must independently calculate the impacts of the topology change on their own routes. Because they must mutually develop an agreement of the new topology independently from different perspectives, they are said to converge on this consensus.

Convergence is necessary because routers are intelligent devices that can make their own routing decisions. This is simultaneously a source ...

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