Routing protocols are distinguished between those that are used within an independent network, the Interior Routing Protocols (IRP), and those that operate between different networks, the Exterior Routing Protocols( EGP).
InTCP/ IP environments, such independent networks of an organization or a company are called autonomous systems( AS). The Interior Routing Protocol used in such autonomous systems supports the exchange of routing information between routers. All Interior Routing Protocols have comparable functionalities. They determine the best route to each destination and they distribute routing information to the different routers. They differ in their routing algorithms with which they determine the best or shortest route.
Interior routing protocols include the Routing Information Protocol( RIP), which is used primarily in Unix environments, the Hello protocol, the Intermediate System to Intermediate System Protocol( IS-IS), and Open Shortest Path First( OSPF).