Enhanced Interior Gateway Routing Protocol.
A route that is currently in an unresolved or un-converged
state. The term active is used because the router is actively
attempting to compute an SDAG.
an sdag is a succesor directed acyclic graph…
A DAG is a directed graph with no directed cycles. That is, it is formed by a collection of vertices and directed edges, each edge connecting one vertex to another, such that there is no way to start at some vertex v and follow a sequence of edges that eventually loops back to v again
Successor Directed Acyclic Graph(SDAG)
When a route to a destination becomes unreachable, it is required
that a router computes a directed graph with respect to the
destination. This decision requires the router to select from the
neighbor topology table a feasible successor.