Computer Networking: A Top-Down Approach, 7/e

In this illustration we see a three-node network at the top and, below it, a series of tables and calculations. The three-node network is comprised of three routers in a triangle: the left point of the triangle is router X, the top point of the triangle is router Y and the right point of the triangle is router Z. X and Y are connected by a line designated as 2; Y and Z are connected by a line designated as 1; and X and Z are connected by a line designated as 7.

Below this we see three rows of nodes, and each node is comprised of three tables. The top node is labeled "Node X table," the middle node is labeled "Node Y table," and the bottom node is labeled "Node Z table." The tables can also be viewed in columns for comparison sake, running left, middle and right. Below all the nodes is a dotted line pointing from left to right, labeled "Time."

Each table is labeled "cost to" across the top and "from" along the left side. The first, left-most column of tables appears like this:

Node x table

	x	y	z
x	0	2	7
y	(infinity)	(infinity)	(infinity)
z	(infinity)	(infinity)	(infinity)

Node y table

	x	y	z
x	(infinity)	(infinity)	(infinity)
y	2	0	1
z	(infinity)	(infinity)	(infinity)

Node z table

	x	y	z
x	(infinity)	(infinity)	(infinity)
y	(infinity)	(infinity)	(infinity)
z	7	1	0

027 in the first table is circled in blue, and blue arrows point from it to the middle and bottom tables in the next (middle) column of tables. 201 in the middle table is circled in blue, and blue arrows point from it to the top and bottom tables in the next (middle) column of tables. 710 in the bottom table is circled in blue, and blue arrows point from it to the top and middle tables in the next (middle) column of tables.

The middle column of tables appears like this:

	x	y	z
x	0	2	3
y	2	0	1
z	7	1	0

	x	y	z
x	0	2	7
y	2	0	1
z	7	1	0

	x	y	z
x	0	2	7
y	2	0	1
z	3	1	0

023 in the first table is circled in blue, and blue arrows point from it to the middle and bottom tables in the next (right-most) column of tables. 310 in the bottom table is circled in blue, and blue arrows point from it to the top and middle tables in the next (right-most) column of tables.

The right-most column of tables appear like this:

	x	y	z
x	0	2	3
y	2	0	1
z	3	1	0

	x	y	z
x	0	2	3
y	2	0	1
z	3	1	0

	x	y	z
x	0	2	3
y	2	0	1
z	3	1	0