300-420 Question 119
Select 3An enterprise network is using Equal-Cost Multi-Path (ECMP) to achieve load sharing across multiple links between routers. However, the network team has noticed uneven utilization of the links. Which of the following actions can help improve load sharing across the ECMP paths?
- A
Enable per-packet load balancing on the routers.
- B
Increase the hashing algorithm granularity to consider Layer 4 information.
- C
Disable ECMP and use a single best path for routing traffic.
- D
Implement Weighted Cost Multi-Path (WCMP) to distribute traffic based on link capacities.
- E
Increase the MTU size on the interfaces participating in ECMP.
Show answer and explanation
Correct answers: A, B, D
Explanation
To achieve better load sharing in an ECMP environment, it is important to optimize the hashing algorithm and consider advanced techniques like per-packet load balancing or WCMP. These methods ensure that traffic is distributed more evenly across multiple links, addressing issues caused by uneven utilization. Disabling ECMP or unrelated configurations like MTU changes do not contribute to solving the problem.
- A. Correct.
Enabling per-packet load balancing ensures traffic is distributed evenly across all available paths; however, it may cause packet reordering for certain applications.
- B. Correct.
Increasing the hashing algorithm granularity to include Layer 4 information (e.g., source and destination ports) can improve traffic distribution by creating better path diversity in the ECMP hash.
- C. Incorrect.
Disabling ECMP would eliminate load sharing altogether, which is not the goal. This option would lead to suboptimal use of available bandwidth.
- D. Correct.
Weighted Cost Multi-Path (WCMP) allows traffic to be distributed proportionally to link capacities, ensuring more balanced utilization of links in specific scenarios.
- E. Incorrect.
Increasing the MTU size on the interfaces does not impact how traffic is distributed across multiple paths and is irrelevant to improving load sharing.