Difference between Interior Gateway Protocol (IGP) and Exterior Gateway Protocol (EGP)

Interior Gateway Protocol (IGP) is a Routing Protocol which is used to find network path information within an Autonomous System.

Known Interior Gateway Protocol (IGP) Routing Protocols are Routing Information Protocol (RIP), Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS)

Exterior Gateway Protocol (EGP) is a Routing Protocol which is used to find network path information between different Autonomous Systems. Exterior Gateway Protocol (EGP) is commonly used in the Internet to exchange routing table information. There is only one Exterior Gateway Protocol (EGP) exists now and it is Border Gateway Protocol (BGP).