A metric value used for load balancing. It can be a value from 1 to 128. The default is 1, which means equal-cost load balancing.
To control load balancing in an EIGRP-based internetwork, use the variance router configuration command. The variance value determines whether IGRP will accept unequal-cost routes. An IGRP router will only accept routes equal to the local best metric for the destination multiplied by the variance value.To reset the variance to the default value, use the no form of this command.
Setting a variance value lets the Cisco IOS software determine the feasibility of a potential route. A route is feasible if the next router in the path is closer to the destination than the current router and if the metric for the entire path is within the variance. Only paths that are feasible can be used for load balancing and included in the routing table.
If the following two conditions are met, the route is deemed feasible and can be added to the routing table:
1. The local best metric must be greater than the metric learned from the next router.
2. The multiplier times the local best metric for the destination must be greater than or equal to the metric through the next router.
The following example sets a variance value of 4:Router(config)#router igrp 109 Router(config-router)#variance 4
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