Dell PowerConnect B-RX Configuration Manual page 783

The router software can use the route information it learns through OSPF to determine the paths
and costs.
destination (in this case, R1).
FIGURE 108
In the example in
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•
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Normally, the BigIron RX will choose the path to the R1 with the lower metric. For example, if R3's
metric is 1400 and R4's metric is 600, the BigIron RX will always choose R4.
However, suppose the metric is the same for all four routers in this example. If the costs are the
same, the router now has four equal-cost paths to R1. To allow the router to load share among the
equal cost routes, enable IP load sharing. The software supports four equal-cost OSPF paths by
default when you enable load sharing. You can specify from 2 – 8 paths.
NOTE
The BigIron RX is not source routing in these examples. The router is concerned only with the paths
to the next-hop routers, not the entire paths to the destination hosts.
OSPF load sharing is enabled by default when IP load sharing is enabled. To configure IP load
sharing parameters, refer to
BigIron RX Series Configuration Guide
53-1002253-01
Figure 108 shows an example of an OSPF network containing multiple paths to a
Example OSPF network with four equal-cost paths
H1
H2
H3
H4
Figure 108, the BigIron RX has four paths to R1:
BigIron RX ->R3
BigIron RX ->R4
BigIron RX ->R5
BigIron RX ->R6
"Configuring IP load sharing"
OSPF Area 0
R3
R1
R4
R5
R6
Configuring OSPF
on page 209.
25
BigIron RX
707