EIGRP Implications of Large Variance Values

EIGRP can be configured with unequal cost load balancing using the variance command. Variance values can is applied using the variance command, and can range from 1 to 128, although some platforms and IOS versions may have slightly different ranges.

Large variance values in network routes enable load balancing across paths with significant metric differences, which can degrade performance. The larger the variance value, the more routes with much worse performance may be considered for load balancing. These routes may have too many hops, increased latency, or much lower bandwidth.

It is advisable to avoid using extremely large variance values to avoid using such routes in load balancing and instead rely on primary, more efficient routes.

Effective load balancing should occur between routes with similar metrics. There is no hard and fast rule, but as a general guideline, variance values should rarely exceed 5 to maintain optimal network performance.

Links

https://networklessons.com/eigrp/eigrp-variance-command-example

https://networklessons.com/eigrp/eigrp-unequal-cost-load-balancing