Open Shortest Path First (OSPF) is a link-state routing protocol that is most often used in large heterogeneous networks to share routing information among routers in the same Autonomous System (AS). Deep Edge supports OSPF version 2 (see RFC 2328) and OSPF version 3 (see RFC 2740).

The main benefit of OSPF is that routing overhead is reduced by only advertising routes when neighbors change state instead of at timed intervals.

OSPF dynamically determines routes by obtaining information from other routers and advertising routes to other routers by way of Link State Advertisements (LSAs). The router keeps information about the links between it and the destination to make highly efficient routing decisions. A cost is assigned to each router interface, and the best routes are determined to be those with the lowest costs, when summed over all the encountered outbound router interfaces and the interface receiving the LSA.

Deep Edge uses hierarchical techniques to limit the number of routes that must be advertised and the associated LSAs.