
Configuring IP Services
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Specifying the Metric Cost
For OSPF, the best path is the one that offers the least-cost metric.
You must configure cost metrics if you want to specify a preferred path. Allow the
preferred path to retain the cost metric value of 1, and then assign higher-cost
metric values to the less-preferred paths.
Figure 7-
5 shows the benefit of using configurable cost metrics. Assigning the
56-Kb line a cost metric value of 10 forces OSPF to choose the faster T1 line path
as the best path, despite the extra hop, when transmitting a packet from Host A to
Host B.
Figure 7-5. Example of Using Configurable Cost Metrics
Router 1
Router 2
Router 3
56 Kb
Assigned cost
metric = 1c
T1
1.544 Mb
Assigned cost
metric = 1
T1
1.544 Mb
Assigned cost
metric = 1
Host
B
Host
A
IP0018A
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