EIGRP Refining the behavior of load balancing with traffic-share
By using the
variance command, EIGRP is able to perform unequal cost load balancing To further refine how this load balancing takes place, you can use the
traffic-share EIGRP command with the following options:
traffic-share balanced- This is the default behavior. Traffic to a particular destination is distributed proportionally to all entries in the routing table based on their metrics.
traffic-share min- Traffic is sent only across the minimum-cost path, even if there are multiple paths in the routing table. If two or more paths have an equal minimum-cost, load balancing will only take place across those paths.
traffic-share min across-interfaces- This is the same as
traffic-share minwith the exception that if there are two or more paths of equal minimum-cost, then load balancing will only occur across them if they have different exit interfaces. This results in better load balancing.
traffic-share min and
traffic-share min across-interfaces seem to cancel out the benefit of the
variance command, since the load-balancing behavior is the same as when the
variance command is not used. However, the benefit of using
traffic-share min with the
variance command is that even though traffic is sent over the minimum-cost path only, all feasible routes get installed into the routing table, which decreases convergence times in the event of a failure or topology change.