300-420 Question 262
Single answerA network engineer is designing a QoS policy for a branch office where real-time voice traffic, critical business applications, and bulk data transfers share the same WAN link. The WAN link has limited bandwidth, and the engineer wants to ensure that real-time voice traffic always gets the highest priority while avoiding starvation of other traffic classes. Which queuing method should the engineer use?
- A
Priority Queuing (PQ)
- B
Weighted Fair Queuing (WFQ)
- C
Low Latency Queuing (LLQ)
- D
Class-Based Weighted Fair Queuing (CBWFQ)
Show answer and explanation
Correct answer: C
Explanation
Low Latency Queuing (LLQ) is the most suitable method for this scenario as it provides a strict priority queue for real-time traffic like voice, ensuring low latency, while also allocating bandwidth to other traffic classes to prevent starvation. This makes it ideal when multiple traffic types share a constrained WAN link.
- A. Incorrect.
Priority Queuing (PQ) provides strict priority to certain traffic but can lead to bandwidth starvation for lower-priority traffic, which is not suitable for this scenario.
- B. Incorrect.
Weighted Fair Queuing (WFQ) ensures fair bandwidth distribution among flows but does not provide the strict priority required for real-time voice traffic.
- C. Correct.
Low Latency Queuing (LLQ) combines strict priority queuing for real-time traffic with class-based queuing for other traffic, preventing starvation of lower-priority classes while ensuring voice traffic is prioritized.
- D. Incorrect.
Class-Based Weighted Fair Queuing (CBWFQ) allows bandwidth allocation for traffic classes but does not include a strict priority queue for real-time traffic, which is essential for voice traffic.