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  1. Hi Rene,

    If we have three path to destination and we configure variance to use the three path just like in your example here :-

    My question is :-
    The traffic will be shared in which way ? to be more clarify, In the begging of this article you said " if the feasible successor has a feasible distance which is 5 times worse than the successor then traffic will be shared in a 5:1 way " so what the rate will be if we have three path to destination ( the successor and tow feasible successors ) ?

  2. i didn’t understand this
    could you explain more details about this . that will be hard when the numbers are high .
    and i show command its show me share count

    Router#show ip route
    Routing entry for
      Known via "eigrp 1", distance 90, metric 156416, type internal
      Redistributing via eigrp 1
      Last update from on FastEthernet0/0, 00:01:11 ago
      Routing Descriptor Blocks:, from, 00:01:11 ago, via FastEthernet0/0
          Route metric is 156416, traffic share count is 240
          Total delay is 5110 microseconds, minimum bandwidth is 100000 Kbit
          Reliability 255/255, minimum MTU 1500 bytes
          Loading 1/255, Hops 2
      *, from, 00:01:11 ago, via Serial5/0
          Route metric is 640256, traffic share count is 59
          Total delay is 5010 microseconds, minimum bandwidth is 5000 Kbit
          Reliability 255/255, minimum MTU 1500 bytes
          Loading 1/255, Hops 1

    Rene Molenaar September 17, 2015 at 13:29 #
    Hi Hussein,

    It will be shared in proportion based on the feasible distance. If the successor had a FD of 100 and the feasible successors had a FD of 20 and 10 then you’d see a 10:2:1 ratio.



  3. Hello Florain

    The FS is a FS only if it is not in the routing table. If it is in the routing table it has the best metric and is thus considered a successor, even if there are more than one such as is the case with EIGRP load balancing.

    If you do unequal cost LB, then the routes in the routing table are also considered successors and not feasable successors. But putting aside terminology, the answer is yes, the routes that were FS (at least the next one(s) in line) is inserted into the routing table and becomes a successor.

    The deciding factor of choosing the next successor is always the same, regardless of whether or not you are using load balancing. EIGRP will keep up to six feasible successors in the topology table and only the one (or ones) with the best metric (or metrics) become the successor(s) and are placed in the routing table.

    I hope this has been helpful!


  4. Hello Marcel

    All routes learned via EIGRP are contained within the topology table, whether they are actively being used (in the routing table) or not. These routes are examined by EIGRP and only the route with the best metric is placed within the routing table. The rest of the routes still exist in the topology table however.

    So, the routing table will only have a single route to a particular destination by default (unless two routes have an equal metric of course). In order to determine if a route can be used for unequal load balancing, the variance value is used and the calculation as described above is implemented on the metrics found in all routes within the topology table. If the metric of the route fulfills the metric * variance > FD condition, then it is then installed in the routing table as well, as a secondary, unequally load balanced route.

    So the topology table is used in this whole evaluation of routes because it is there that all the available routes and their metrics are found.

    I hope this has been helpful!


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