IGP vs EGP
What is the difference between IGP and EGP? Well, IGP stands for Interior Gateway Protocol while the EGP stands for Exterior Gateway Protocol. Of course, this defines nothing and there’s allot more to this difference.
Basically, the difference between IGP and EGP could be explained through the names of these terms.
IGP meaning Interior Gateway Protocol means that this protocol is used for networks within one organization, while on the other hand, the exterior one is meant for use by two different networks from two different organizations.
I would consider the Exterior Gateway Protocol as a more complex one, as it requires a few settings before use such as identifying the neighboring routers so it can exchange router information and the number of autonomous systems on a local router.
The autonomous system is isolated by the protocol which is controlled by another organization. Anyhow, before this is all done, both networks must have set up a communication protocol for their two different systems.