OSPFv2 (Open Shortest Path First version 2) is a routing protocol which is
described in RFC2328 entitled OSPF Version 2. It is a Link State-based
IGP(Interior Gateway Protocol) routing protocol. It is widely used in medium
to large-sized enterprise networks.

The characteristics of OSPFv2 are:

• Provides a loop free topology using SPF algorithm.
• Allows hierarchical routing using area 0 (backbone area) as the top of the
  hierarchy.
• Supports load balancing with equal cost routes for same destination.
• OSPFv2 is a classless protocol and allows for a hierarchical design with
  VLSM(Variable length subnet masking) and route summarization.
• Provides authentication of routing messages.
• Scales enterprise size network easily with area concept.
• Provides fast convergence with triggered, incremental updates via
  Link State Advertisements (LSAs).