EIGRP - Unequal Cost Path Load Balancing (Variance) (Cisco Systems)

How Does Unequal Cost Path Load Balancing (Variance) Work in IGRP and EIGRP? (Cisco Systems)
In general, load balancing is the capability of a router to distribute traffic over all the router network ports that are the same distance from the destination address. Load balancing increases the utilization of network segments, and so increases effective network bandwidth. There are two types of load balancing:
Equal cost path
Unequal cost path

Variance
router eigrp 1
network x.x.x.x
variance 2

Traffic Sharing
router eigrp 1
network x.x.x.x
variance 2
traffic-share balanced

traffic-share min across-interfaces
Similarly, when you use the traffic-share command with the keyword min, the traffic is sent only across the minimum-cost path, even when there are multiple paths in the routing table.
router eigrp 1
network x.x.x.x
variance 3
traffic-share min across-interfaces

Load Balancing in CEF
configure terminal
interface serial 0
ip load-sharing per-packet


How Does Unequal Cost Path Load Balancing (Variance) Work in IGRP and EIGRP? (PDF)