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
OSPF Version 2
The OSPF Not-So-Stubby Area (NSSA) Option
Graceful OSPF Restart
Traffic Engineering (TE) Extensions to OSPF Version 2
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
The OSPF Opaque LSA Option
Point-to-Point Operation over LAN in Link State Routing Protocols
OSPF Extensions in Support of Inter-Autonomous System (AS) MPLS and GMPLS Traffic Engineering
OSPF Link-Local Signaling
Advertising a Router's Local Addresses in OSPF Traffic Engineering (TE) Extensions