Open Shortest Path First (OSPF) Protocol:
It is a Link-State dynamic routing protocol used primarily in large networks. It routes packets within an AS (Autonomous System) – Interior gateway protocol (IGP). OSPF networks as assigned an Area identifier (32 bit length). The area identifier can be same as the IP address. OSPF can handle duplicate ip addresses without any conflict.
OSPF does not use UDP or TCP but rather directly encapsulated into IP datagrams.
OSPF areas include Backbone area (area 0), Stub area, not so stubby area (NSSA).
Border Gateway Protocol (BGP):
It is a path-vector based dynamic protocol that is widely used in ISP. It is an exterior gateway protocol (EGP)