2. Link State routing protocols

The principle behind a Link State routing protocol is to provide all routers in a given "area" with a complete view of the area's topology. In this way, each router can build a coherent routing table, generally choosing the shortest path criterion. Most current implementations [whether OSPF (Open Shortest Path First) or IS-IS] are content to characterize a link through a single "generic" metric, which will be interpreted by the decision-making process as the cost of using the link. This section describes the general characteristics of Link State routing protocols.