OSPF protocol is an Interior Gateway Protocol used to distribute routing information within a single autonomous system. Routers use link-state algorithms to send routing information to all nodes in an inter-network by calculating the shortest path to each node based on the complete routing structure, or the topography, of the Internet constructed by each node. Routing tables keep track of routes to particular network destinations. Each router sends the portion of the routing table that describes the state of its own links to the nodes in the inter-network. The routers also send the topography of the inter-network to the nodes.