Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 275)

Disable or re-enable load sharing
Brocade devices can load share among up to eight equal-cost IP routes to a destination. By default, IP
load sharing is enabled. The default is 4 equal-cost paths but you can specify from 2 - 8 paths. The
router software can use the route information it learns through OSPF to determine the paths and costs.
FIGURE 26 Example OSPF network with four equal-cost paths
The device has four paths to R1:
• Router ->R3
• Router ->R4
• Router ->R5
• Router ->R6
Normally, the device will choose the path to the R1 with the lower metric. For example, if the metric for
R3 is 1400 and the metric for R4 is 600, the device 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 device is not source routing in these examples. The device 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.
Disable or re-enable load sharing
FastIron Ethernet Switch Layer 3 Routing Configuration Guide 275
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