300-420 Question 117
Single answerAn enterprise network is designed with two WAN links connecting the branch office to the headquarters. The design goal is to achieve load sharing by utilizing both links simultaneously, while ensuring minimal configuration complexity. Which method would best achieve this design goal?
- A
Configure Equal-Cost Multi-Path (ECMP) routing using OSPF.
- B
Use Policy-Based Routing (PBR) to direct traffic across both links.
- C
Implement a link aggregation protocol such as EtherChannel across the WAN links.
- D
Manually configure static routes with different metrics for each link.
Show answer and explanation
Correct answer: A
Explanation
Equal-Cost Multi-Path (ECMP) routing is the most effective solution for achieving load sharing with minimal configuration complexity. It allows multiple links with the same cost to share traffic dynamically, ensuring an efficient and balanced use of resources. Other methods, such as Policy-Based Routing or static routes, require more manual effort and lack the dynamic adaptability of ECMP.
- A. Correct.
ECMP (Equal-Cost Multi-Path) routing, available in OSPF and other routing protocols, automatically shares traffic across multiple links with equal cost, making it an efficient and simple solution for load sharing in this scenario.
- B. Incorrect.
While Policy-Based Routing (PBR) can achieve load sharing, it involves more manual configuration complexity and lacks the dynamic adaptability offered by ECMP.
- C. Incorrect.
EtherChannel is not suitable for WAN links as it is typically used for bundling physical links within a single broadcast domain, such as on a LAN or between switches.
- D. Incorrect.
Manually configuring static routes with different metrics does not achieve simultaneous load sharing, as traffic will always prefer the route with the lower metric unless the link fails.