This imaginary voyage is similar to a datagram traversing an Internet, and the road signs are analogous to routing tables in routers along the path. These are the two main questions that all routing protocols try to answer, each in its own way. We shall now, therefore, look at the technical background of routing and at some routing protocols found in use today. Automatic Route Propagation One of the functions of a router is to communicate routing information to other nearby routers. Connections fail and are later replaced.
Networks can become overloaded or underused.
The purpose of routing propagation mechanisms is not merely to find a set of rules, but to continually update the information. Humans simply cannot respond to changes fast enough.