Hello all. My question is - how does EIGRP do unequal path load balancing? I know that you can utilize the variance command to install unequal cost paths in the EIGRP routing table. My question is - after EIGRP has installed the unequal metric paths into the routing table, how does the load-balancing to the destination occur? Does CEF or process switching perform the load-balancing? Is the load-balancing at a ratio of 1:1 between these 2 unequal paths or does the variance command or interface bandwidth influence the load-balancing ratio? Please answer only if you are definite. I'm trying to clear up some confusion. Thanks in advance!
EIGRP is only responsible for getting routes into the routing table. EIGRP does not do load balancing. The load balancing is done by CEF (or whichever switching path the router is currently using).
Here is a good post from a Cisco expert describing how CEF does the load balancing and does maintain the ratios of the unequal links as it does unequal load sharing: