Information Technology Reference
In-Depth Information
Study Guide
Introduction to OSPF
Open Shortest Path First (OSPF) is a link-state routing protocol that was developed as a replacement
for the distance vector Routing Information Protocol (RIP). RIP was an acceptable routing protocol in
the early days of networking and the Internet, but its reliance on hop count as the only measure for
choosing the best route quickly became unacceptable in larger networks that needed a more robust
routing solution. OSPF is a classless routing protocol that uses the concept of areas for scalability.
RFC 2328 defines the OSPF metric as an arbitrary value called cost. Cisco IOS Software uses band-
width as the OSPF cost metric. In the following sections of the Study Guide, you will review basic
OSPF concepts and protocols.
