RIP

The Routing Information Protocol (RIP) is one of the oldest, and still widely used, interior gateway protocols (IGP). RIP uses only the number of hops between nodes to determine the cost of a route to a destination network and does not consider network congestion or link speed. Other shortcomings of RIP are that it can create excessive network traffic if there are a large number of routes and that it has a slow convergence time and is less secure than other IGPs, such as OSPF.

Routers using RIP broadcast their routing tables on a periodic basis to other routers, whether or not the tables have changed. Each update contains paired values consisting of an IP network address and a distance to that network. The distance is expressed as an integer, the hop count metric. Directly connected networks have a metric of 1. Networks reachable through one other router are two hops, and so on. The maximal number of hops in a RIP network is 15 and the protocol treats anything equal to or greater than 16 as unreachable.