Solution overview
ISIS and OSPF are the two primary routing protocols used within a Core Routing network. As Link-state routing protocols, ISIS and OSPF both work by building complete network topology tables on each router, and then having each router independently calculate the best next hop routes to every possible destination. This functionality is often referred to as "interior routing" or "underlay routing" because it enables all the routers within a network to establish reachability to one another. Once that reachability is established (like an "underlay" foundation), then the network can provide signaled services such as L2VPN and L3VPN over the top, as well as perform advanced functions like traffic engineering.
This lab explores how to configure ISIS and get familiar with its function as an underlay routing protocol.