You administer the EIGRP network shown above. The bandwidth (Bw) and delay (D) values are displayed above each link. RouterA uses the default variance value.
Which of the following statements are correct?
| A. |
RouterB is a successor for the 172.20.0.0/24 network. | |
| B. |
RouterC is a successor for the 172.20.0.0/24 network. | |
| C. |
RouterD is a successor for the 172.20.0.0/24 network. | |
| D. |
RouterE is a successor for the 172.20.0.0/24 network. | |
| E. |
RouterA will not perform load balancing. | |
| F. |
RouterA will perform unequal cost load balancing. |
RouterD is a successor for the 172.20.0.0/24 network. Additionally, RouterA will not perform load balancing.
A successor is a router with the lowest metric to a destination network. By default, the Enhanced Interior Gateway Routing Protocol (EIGRP) composite metric is calculated by bandwidth and delay. Higher bandwidth values create lower metric values. By contrast, lower delay values create lower metric values. Therefore, higher bandwidth values and lower delay values are preferred over lower bandwidth values and higher delay values. RouterD is a successor for the 172.20.0.0/24 network because the path through RouterD has the highest bandwidth and the lowest delay. Therefore, RouterD is the only successor for the 172.20.0.0/24 network.
RouterB is not a successor for the 172.20.0.0/24 network. Although the bandwidth through RouterB is the same as the bandwidth through RouterD, the delay through RouterB is higher than the delay through RouterD.
RouterC is not a successor for the 172.20.0.0/24 network. Although the delay through RouterC is the same as the delay through RouterD, the bandwidth through RouterC is lower than the bandwidth through RouterD.
RouterE is not a successor for the 172.20.0.0/24 network. The bandwidth through RouterE is lower than the bandwidth through RouterD. Additionally, the delay through RouterE is higher than the delay through RouterD.
RouterA will not perform load balancing. By default, an EIGRP router is configured with a variance value of 1, which enables the router to perform equalcost load balancing. However, there are no routes with a metric value as low as the route through RouterD. Ifthere were another path to the 172.20.0.0/24 network with a bandwidth of 100 and a delay of 10, RouterA would load balance traffic between the two equal cost paths.
Although EIGRP is capable of unequal cost load balancing, RouterA is not configured to perform unequal cost load balancing, because RouterA is using the default variance value of 1. A variance value of 2 or higher means that a feasible successor can be used for unequalcost load balancing. However, voice traffic and other delay sensitive traffic will be negatively affected if those packets are routed over paths with lower bandwidths and higher delays.