Routing - Difference between IGPs and EGPs

IGPs are used in order to route traffic within an Autonomous System (AS). Such protocols include EIGRP OSPF and IS-IS.

Exterior Gateway Protocols (EGPs) are used in order to route traffic between ASs. BGP is an example of an EGP. BGP is currently the only EGP in any production network today and is the routing protocol used on the Internet.

BGP has virtually completely replaced the older legacy EGP protocol, which itself is also called Exterior Gateway Protocol (EGP). This can be confusing, however, it must be noted that both the category of routing protocols, and this legacy protocol, which is no longer used, have the same name.