Chapter 6

1:	What is the basic application of the SPF algorithm?
A:	The SPF algorithm was designed to find the shortest distance between two points in any problem that can be modeled as a graph.
2:	What is a directed graph, and how is an internetwork modeled as a directed graph?
A:	A directed graph or digraph consists of the set of vertices and the set of interconnections between the vertices referred to as arcs or directed edges. An internetwork is modeled as a directed graph by representing the network nodes or routers as vertices and the network links (adjacencies) as arcs. Bidirectional traffic flow is depicted by parallel opposite arrows.
3:	Name the three lists used in the operation of the Dijkstra algorithm for computing IS-IS routes.
A:	Paths, Tentative, and Unknown.
4:	What is the estimated processing cost of the Dijkstra algorithm?
A:	The computational cost directly dependent on the complexity of execution of Dijkstra algorithm, which is of the order, O( L log N ), where L is the number of links and N is the number of nodes.
5:	What is the difference between a full SPF and a partial route calculation (PRC)?
A:	A full SPF is a complete computation of the shortest path tree (SPT) caused by an adjacency change. PRC is a partial computation of the SPF algorithm and performed when only an IP prefix change is reported in a new LSP.