OSPF Vs EIGRP

OSPF has quick convergence. It is a classless, link-state routing protocol. OSPF uses Dijkstra algorithm to calculate shortest paths (routing table) using cost as the metric. The OSPF router discovers its neighbors on each interface using Hello packets. The list of neighbors is kept in a neighbor table. The routers keep in touch with their neighbors by sending occasional Hello packets to each other instead of full routing updates.

EIGRP is a hybrid routing protocol which supports VLSM, route summarization and secure authentication of all neighbors. EIGRP routes are marked (P)assive, which means good. If the route was marked as (A)ctive, it would indicate the router is actively trying to find a replacement route since the primary route had failed. This is called query process, that occurs when the primary route (successor) fails and there is no backup route (feasible successor) for that destination. In order for the route to be a feasible successor, its advertised distance must be less than the feasible distance of the successor route. EIGRP does not send full routing table to its neighbors.