The routing table contains a list of decisions.
When a routing process does a routing table lookup for a destination network, it finds the best path in accordance with the routing decision that was made earlier.
If the routing process knows of several paths to a remote network, it chooses the most efficient path based on its metric and routing algorithm, and places this into the routing table.
If there is more than one path with the same metric, the routing process may add up to six of these paths and then distribute the traffic equally between them. This is routing protocol-dependent.
It is also possible in IGRP and EIGRP to load-share over unequal cost paths by using the variance command. This is something to take into consideration when designing the network.
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