D-Link DES-3326SRM, Руководство по эксплуатации продукта

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D-Link DES-3326S Layer 3 Switch
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 23- 2. 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:
Router A
Router B
Router C
128.213.0.0
192.213.11.0
222.211.10.0
0
10
10
5
10
Figure 23- 3. Constructing a Shortest Path Tree - Completed
Note that this shortest path tree is only from the viewpoint of Router A. The cost of the link from Router B to Router A, for
instance is not important to constructing Router A’s shortest path tree, but is very important when Router B is constructing its
shortest path tree.
Note also that directly connected networks are reached at a cost of 0, while other networks are reached at the cost calculated in
the shortest path tree.
Router A can now build its routing table using the network addresses and costs calculated in building the above shortest path
tree.
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