A link-state protocol that routers use to exchange IP packets over the shortest available end-to-end path based on link-state advertisements from other routers. Router advertisements identify the direction, availability, and cost of links to other routers.With that information, the originating router is able to determine its exit port that leads to the shortest available path to the destination router. OSPF is an Interior Gateway Protocol (IGP) used to exchange path information between routers in the same network domain. See also domain, IGP, IP, link-state protocol, packet, path, port, and router.