OSPF is link-state routing protocol
RIP, IGRP and EIGRP are distance-vector (routing by rumor) routing protocols, susceptible to routing loops, split-horizon, and other issues.
OSPF has fast convergence
RIP and IGRP hold-down timers can cause slow convergence.
OSPF supports VLSM and CIDR
RIPv1 and IGRP do not
Cisco’s OSPF metric is based on bandwidth
RIP is based on hop count; IGRP/EIGRP bandwidth, delay, reliability, load
OSPF only sends out changes when they occur.
RIP sends entire routing table every 30 seconds, IGRP every 90 seconds
Extra: With OSPF, a router does flood its own LSAs when it age reaches 30 minutes (later)
OSPF also uses the concept of areas to implement hierarchical routing
Two open-standard routing protocols to choose from:
RIP, simple but very limited, or OSPF, robust but more sophisticated to implement. IGRP and EIGRP are Cisco proprietary