300-420 Question 118
Single answerA company has two WAN links connecting its headquarters to a branch office. To implement load sharing, the network engineer configures two static routes with equal administrative distances but different cost metrics. However, during testing, the engineer notices that only one link is being used for forwarding traffic. What could be the reason for this behavior?
- A
The router only supports load sharing with dynamic routing protocols.
- B
The static routes must have equal cost metrics for load sharing to work.
- C
The router requires per-packet load balancing to be explicitly enabled.
- D
Equal-cost multi-path (ECMP) is not supported on the router's platform.
Show answer and explanation
Correct answer: B
Explanation
Load sharing with static routes requires the routes to have equal cost metrics so that the router considers them as equal-cost paths. In this scenario, the static routes were configured with different cost metrics, causing the router to prefer the lower-cost route and ignore the other. By ensuring the cost metrics are equal, the router can then utilize both links for load sharing, assuming ECMP is supported.
- A. Incorrect.
This is incorrect because static routes can support load sharing, but the configuration must meet specific conditions such as equal cost metrics.
- B. Correct.
This is correct because for load sharing to occur, the static routes must have equal cost metrics. With unequal metrics, the router will prefer the route with the lower cost.
- C. Incorrect.
This is incorrect because per-packet load balancing is not required for general load sharing. Load sharing can also be implemented on a per-destination basis, which is more common.
- D. Incorrect.
This is incorrect because most modern routers support ECMP for load sharing, and the issue here is not about platform support but rather the configuration of the static routes.