300-445 Question 135
Single answerAn enterprise has deployed a VoIP system across its global offices. Employees are reporting poor voice quality during calls, particularly during peak hours. After initial investigation, you determine that Quality of Service (QoS) policies are not effectively prioritizing voice traffic. Which QoS mechanism should be implemented to ensure consistent voice quality across the network?
- A
Implement Weighted Fair Queuing (WFQ) for all traffic types, including voice
- B
Configure Low Latency Queuing (LLQ) to prioritize voice traffic over other types of traffic
- C
Enable Random Early Detection (RED) to manage congestion for voice packets
- D
Increase the overall bandwidth on all WAN links to accommodate more traffic, including voice
Show answer and explanation
Correct answer: B
Explanation
Low Latency Queuing (LLQ) is the most suitable QoS mechanism for voice traffic because it ensures that voice packets are given strict priority over other traffic types. This minimizes latency, jitter, and packet loss, which are critical for maintaining high-quality voice communication. Other mechanisms such as WFQ, RED, or simply increasing bandwidth do not directly address the specific requirements of voice traffic.
- A. Incorrect.
WFQ provides fairness by dividing bandwidth among various traffic types, but it does not guarantee the low-latency and priority handling needed for voice traffic.
- B. Correct.
LLQ is designed specifically for prioritizing delay-sensitive traffic such as voice and video. It provides strict priority queuing for voice packets, ensuring consistent voice quality.
- C. Incorrect.
RED is a congestion avoidance mechanism that works by selectively dropping packets. It is not suitable for ensuring voice quality since voice traffic requires low latency and no packet loss.
- D. Incorrect.
Increasing bandwidth may temporarily alleviate congestion, but it does not address the need for prioritizing voice traffic. Without proper QoS mechanisms, voice quality issues may persist.