Interior Gateway Protocols (IGP)

In a nationwide network such as the current Internet, it is very unlikely that a single routing protocol will used for the whole network. Rather, the network will be organized as a collection of "autonomous systems". An autonomous system will in general be administered by a single entity, or at least will have some reasonable degree of technical and administrative control. Each autonomous system will have its own routing technology.

- C. Hedrick; Routing Information Protocol; RFC 1058; June 1988.