Dynamic routing

Dynamic routing is when protocols are used to find networks and update routing tables on routers. Using dynamic routing is easier than using static or default routing, but it’ll cost you more in terms of router CPU processes and bandwidth on the network links. A routing protocol defines the set of rules used by a router when it communicates routing information between neighbor routers.

Two types of routing protocols are used in internetworks: interior gateway protocols (IGPs) and exterior gateway protocols (EGPs). IGPs are used to exchange routing information table with routers in the same autonomous system (AS). An AS is a collection of networks under a common administrative domain, which basically means that all routers sharing the same routing table information are in the same AS. EGPs are used to communicate between ASes. An example of an EGP is Border Gateway Protocol (BGP).  Routing protocols are essential to dynamic routing. There are three different kinds of routing protocols. See Types of routing protocols