An interiorgatewayprotocol (IGP) or Interior routing protocol is a type of routing protocol used for exchanging routing table information between gateways (commonly routers) within an autonomous system (for example, a system of corporate local area networks). This routing information can then be used to route network-layer protocols like IP.
InteriorGateway Routing Protocol (IGRP) is a distance vector interiorgatewayprotocol (IGP) developed by Cisco. It is used by routers to exchange routing data within an autonomous system.