The most widely used exterior gateway protocol is the Border Gateway Protocol (BGP), the principal routing protocol between autonomous systems on the Internet. The IS-IS is another link-state dynamic routing protocol, which is more common in large service provider networks. The Open Shortest Path First (OSPF) is a routing protocol for wide area networks and enterprise network. OSPF is perhaps the most widely used interior gateway protocol (IGP) in large enterprise networks. Another post related to CCNA Certification and this time learn how to configure OSPF routing? The configuration of the OSPF routing protocol is easy as RIP Routing.