300-440 Question 70
Single answerA network engineer is configuring load balancing over two WAN links between Site A and Site B. The primary link has a cost of 10, while the backup link has a cost of 20. The engineer wants to enable unequal-cost load balancing for traffic. Which routing protocol and configuration are required to achieve this?
- A
Use EIGRP with variance configured to 2.
- B
Use OSPF and configure multiple equal-cost paths.
- C
Use BGP with local-preference tuning.
- D
Use RIP and configure the maximum-paths parameter.
Show answer and explanation
Correct answer: A
Explanation
EIGRP is the only routing protocol among the options that supports unequal-cost load balancing. This is achieved using the variance command, which allows the use of backup paths with a metric within a specific multiple of the best path's metric. In this scenario, configuring a variance of 2 would allow traffic to be distributed across the primary and backup links with costs of 10 and 20, respectively.
- A. Correct.
Correct. EIGRP supports unequal-cost load balancing by using the variance command, which allows traffic to be distributed across paths with different metrics if the metrics fall within the variance multiplier.
- B. Incorrect.
Incorrect. OSPF only supports equal-cost load balancing. It cannot perform unequal-cost load balancing, as it only uses paths with the same metric.
- C. Incorrect.
Incorrect. BGP does not inherently support unequal-cost load balancing. Local-preference tuning is used to influence path selection, not load balancing.
- D. Incorrect.
Incorrect. While RIP can perform load balancing, it only supports equal-cost load balancing, not unequal-cost load balancing.