300-420 Question 245
Select 2A global enterprise network is experiencing voice and video quality issues due to congestion during peak hours. As the network designer, you need to implement end-to-end QoS policies to ensure consistent performance for voice traffic. Which two design considerations should you prioritize to achieve this goal?
- A
Classify and mark voice traffic as EF (Expedited Forwarding) as close to the source as possible.
- B
Configure Weighted Random Early Detection (WRED) for voice traffic for congestion avoidance.
- C
Implement low latency queuing (LLQ) to prioritize voice traffic in the network.
- D
Set voice traffic to a lower priority than data traffic to ensure fairness during congestion.
- E
Use traffic policing to limit voice traffic to a strict maximum bandwidth at every hop.
Show answer and explanation
Correct answers: A, C
Explanation
To ensure consistent voice quality in an enterprise network, the design must prioritize voice traffic by classifying and marking it with EF (Expedited Forwarding) close to the source and implementing Low Latency Queuing (LLQ) to prioritize it across the network. These techniques ensure low delay, jitter, and no packet loss for voice traffic, which are critical for maintaining quality.
- A. Correct.
Classifying and marking voice traffic as EF close to the source ensures that QoS policies differentiate voice traffic from other types and treat it with the highest priority throughout the network.
- B. Incorrect.
WRED is used for congestion avoidance and is not suitable for real-time traffic like voice, as dropping voice packets can severely degrade call quality.
- C. Correct.
Low latency queuing (LLQ) ensures that voice traffic is given the highest priority in the queuing process, minimizing delay and jitter.
- D. Incorrect.
Setting voice traffic to a lower priority than data traffic is counterproductive as voice requires minimal delay and jitter for acceptable quality.
- E. Incorrect.
Traffic policing limits bandwidth but can result in dropped packets, which is not ideal for voice traffic that requires consistent bandwidth and minimal loss.