Routing Protocol

Interior Gateway Protocols (IGP)

Used inside a Autonomous System

OSPFOpen Shortest Path FirstMost commonly used, IP layer
IS-ISIntermediate System to Intermediate SystemLink layer
EIGRPEnhanced Interior Gateway Routing ProtocolCisco semi-proprietary
RIPRouting Information ProtocolOld, rarely used

Routing Tables

The goal of the routing protocols we talked about above is to help routers across the Internet build their routing tables.

Routing Algorithm