| Distance-Vector Routing
				Distance-vector routing makes this assumption:
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					Each router knows the identity of every other router in the network.
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				In an attempt to enforce this assumption, each router will maintain a
				distance vector, comprised of the list of tuples:
				 
				< destination, cost > 
				... for all nodes in the network. Here, costis the
				current estimate of the shortest path from this
				router to the destination; the estimate is never
				smaller than the real cost of the path. 
				The distance-vector algorithm is a distributed implementation of the 
				
				Bellman-Ford algorithm:
				 
					Each router periodically sends a copy of its distance vector to its neighbors.
					
					When a router receives a distance vector from a neighbor, it determines 
					whether its cost of reaching any destination would decrease if packets 
					to that destination were to be sent through that neighbor.
					
					If so, that router updates its own distance vector.
					
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