D-Link xStack DGS-3600 Series User Manual - Shortest Path Tree
xStack DGS-3600 Series Layer 3 Gigabit Ethernet Managed Switch
Shortest Path Tree
To build Router A’s shortest path tree for the network diagramed below, Router A is put at the root of the tree and the smallest
cost link to each destination network is calculated.
Figure 8- 24. Constructing a Shortest Path Tree
Router A
Router B
Router C
Router D
128.213.0.0
192.213.11.0
222.211.10.0
0
10
10
5
5
10
10
Figure 8- 25. Constructing a Shortest Path Tree
The diagram above shows the network from the viewpoint of Router A. Router A can reach 192.213.11.0 through Router B with a
cost of 10 + 5 = 15. Router A can reach 222.211.10.0 through Router C with a cost of 10 + 10 = 20. Router A can also reach
222.211.10.0 through Router B and Router D with a cost of 10 + 5 + 10 = 25, but the cost is higher than the route through Router
C. This higher-cost route will not be included in the Router A’s shortest path tree. The resulting tree will look like this:
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