"variance" command enables load balancing over unequal cost paths. It uses a value known as multiplier. the command must be issued from router configuration mode:
router(config)#router eigrp [AS-number]
router(config-router)#variance [value]
and the operation is like this. the process will multiply the best path cost by the multiplier, and any path that its cost is less or equal to the value obtained from this operation will be used for load balancing.
for example:
assume I have three paths with costs (100, 300, 400)
to load balacne over only two paths use a value of 3 for "variance" command, because 100*3 = 300, and third path will not be used because it has a cost of 400 > 300.
