300-420 Question 244
Single answerAn enterprise network is experiencing voice call degradation during peak traffic hours. The network engineer is tasked with designing an end-to-end QoS policy to prioritize voice traffic while ensuring other critical applications also have sufficient bandwidth. Which approach should the engineer implement to meet these requirements?
- A
Use a single default queue for all traffic and rely on TCP congestion control to manage bandwidth.
- B
Implement a three-tier QoS model with classification, marking, and queuing policies to prioritize voice traffic.
- C
Apply a best-effort QoS policy across the network to ensure fairness for all applications.
- D
Use policing to strictly limit non-voice traffic and drop excess packets above the configured threshold.
Show answer and explanation
Correct answer: B
Explanation
In an end-to-end QoS design, using a three-tier QoS model is best practice. It ensures traffic is classified and marked at the ingress point, enabling the network to prioritize voice traffic using queuing policies while maintaining fairness for other critical applications. This approach effectively addresses voice call degradation and optimizes resource allocation.
- A. Incorrect.
Using a single default queue for all traffic does not differentiate between traffic types, which can lead to voice traffic competing with other data, causing degradation.
- B. Correct.
A three-tier QoS model with classification, marking, and queuing policies allows traffic to be identified, prioritized, and handled appropriately, ensuring voice traffic receives the necessary resources.
- C. Incorrect.
A best-effort QoS policy does not prioritize any traffic, which would not solve the issue of voice call degradation during peak times.
- D. Incorrect.
Policing non-voice traffic may restrict bandwidth for other critical applications and result in packet loss, which is not an effective solution in this scenario.