The dijkstra algorithms four steps to discover what it called the shortest path tree .
a.The algorithm beings to build the tree identifying its root. The root of each router tree is the router itself. The algorithm them attaches all nodes that can be reached from that root in other words. All of the other neighbour nodes and are are temporary at this step.
b.The algorithm compares the tree temporary acres and identifies the are with the lowest commutative cost. This are and the node to which it connecters are now a permanent part of shortest path tree.
c.The algorithm examines the database and identifies every node that can be reached from it chosen node. These nodes and their arcs are added temporarily to the tree.
d.The last two steps are repeated until every node in the network has become a permanent part of the tree. The only permanent arcs are those that represent the shortest route to every node.
The cost number next to each node represents the cumulative cost from the root node not the cost of the individual arc. The second third steps repeated until four more nodes have becomes permanent.