Interior Gateway Protocol (IGP) is a routing protocol that uses intradomain routing to disseminate routing and reachability information in an autonomous system( AS). IGP is an IP protocol for exchanging routing information in autonomous systems.
Although there is no single standard for the IGP protocol, the RIP protocol is the most popular. The IGP protocol is topology independent. Since different topologies and networks exist, there are multiple interior gateway protocols. Gateways can use different routing protocols simultaneously if they are the connection between autonomous systems and a higher- level backbone network. In addition to the Routing Information Protocol (RIP) mentioned above, the Hello protocol, the Interior Gateway Routing Protocol( IGRP) and Open Shortest Path First( OSPF) are available for this purpose.