OSPF is a link-state routing protocol. It is designed to be run internal to a single Autonomous System. Each OSPF router maintains an identical database describing the Autonomous System's topology. From this database, a routing table is calculated by constructing a shortest-path tree.
Multicast Extensions to OSPF
Extending OSPF to Support Demand Circuits
The OSPF Not-So-Stubby Area (NSSA) Option
Graceful OSPF Restart
Extensions to OSPF for Advertising Optional Router Capabilities
Using a Link State Advertisement (LSA) Options Bit to Prevent Looping in BGP/MPLS IP Virtual Private Networks (VPNs)
OSPF as the Provider/Customer Edge Protocol for BGP/MPLS IP Virtual Private Networks (VPNs)
OSPF Out-of-Band Link State Database (LSDB) Resynchronization
OSPF Restart Signaling
Multi-Topology (MT) Routing in OSPF
Extensions to OSPF for Advertising Optional Router Capabilities
OSPF Protocol Extensions for Path Computation Element (PCE) Discovery
OSPFv3 Graceful Restart
The OSPF Opaque LSA Option
Point-to-Point Operation over LAN in Link State Routing Protocols
Traffic Engineering Extensions to OSPF Version 3
OSPF Extensions in Support of Inter-Autonomous System (AS) MPLS and GMPLS Traffic Engineering
OSPF for IPv6
OSPF Link-Local Signaling
Advertising a Router's Local Addresses in OSPF Traffic Engineering (TE) Extensions
Support of Address Families in OSPFv3