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CCNA Quick Reference Sheets (CCNA Exam 640-802) by Jim Doherty, Eric Rivard

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Chapter 5. Implementing OSPF in a Single Area

OSPF is an interior gateway protocol based on link state rather than distance vectors. OSPF uses Dijkstra’s shortest path first (SPF) algorithm to determine the best path to each network. OSPF was developed in the 1980s as an answer to RIP’s inability to scale well in large IP networks.

OSPF is an open-standard, classless protocol that converges quickly and uses costs as a metric. Cisco IOS automatically calculates cost based on the interface bandwidth.

When a router is configured for OSPF, the first thing the router does is create a topology table of the network. OSPF does this by sending Hellos out each OSPF interface, while listening for Hellos from other routers. If the routers share a common data ...

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