EIGRP Maximum Paths and Variance

In EIGRP, maximum paths refer to the maximum number of paths that can be used for load balancing traffic over equal-cost paths. By default, EIGRP load-balances traffic over four equal-cost paths. This can be increased up to a maximum of 16 paths using the maximum-paths command in EIGRP configuration mode.

For example, to set the maximum paths to 8, the following command can be used:

Router(config-router)# maximum-paths 8

The variance command in EIGRP configuration mode is used to allow unequal-cost load balancing, where EIGRP considers paths with different metric values when choosing multiple paths to a destination. The variance value is a multiplier that is applied to the best metric of the path to determine which paths are considered feasible successors.

For example, if the best path to a destination has a metric of 100, and the variance is set to 2, then EIGRP considers all paths with a metric less than or equal to 200 as feasible successors.

To configure variance in EIGRP, use the following command:

Router(config-router)# variance <value>

where <value> is the multiplier value for the best path metric. For example, variance 2 means that EIGRP will consider all paths with a metric of up to twice the best path metric as feasible successors. It is important to note that unequal-cost load balancing should be used with caution, as it can result in suboptimal routing and can cause routing loops in some cases. It is recommended to perform careful testing and validation before enabling unequal-cost load balancing in a production network.