Priority Queuing (PQ) is a Quality of Service (QoS) scheduling algorithm that services queues based on a strict priority hierarchy. It always dequeues packets from the highest-priority queue first. As long as there are packets in the highest-priority queue, no other queue is serviced. This ensures that the most critical traffic experiences the lowest possible latency and jitter. However, a major drawback of this method is "starvation," where a continuous flow of high-priority traffic can prevent lower-priority queues from ever being serviced, denying them any bandwidth. PQ does not provide minimum bandwidth guarantees.

B. The highest priority queue is not inherently reserved for voice traffic; its use is determined by network policy, though delay-sensitive traffic like voice is a common candidate.

D. PQ provides no minimum bandwidth guarantees. This is a feature of other queuing mechanisms like Class-Based Weighted Fair Queuing (CBWFQ).

1. Cisco Systems

Inc.

"Congestion Management Overview" in QoS: Congestion Management Configuration Guide

Cisco IOS XE Release 3S. The section on "Priority Queuing" states: "PQ ensures that important traffic gets the quickest handling at the expense of other traffic... If traffic in a higher-priority queue is constant

traffic in all lower-priority queues can be completely blocked (a condition called starvation)." This directly supports answers A and C.

2. Kurose

J. F.

& Ross

K. W. (2017). Computer Networking: A Top-Down Approach (7th ed.). Pearson. In Chapter 7

Section 7.2.2 "Scheduling

" the text describes Priority Queuing: "a packet from a low-priority queue can be transmitted only when all of the higher-priority queues are empty... a continuous stream of high-priority packets can block out all low-priority packets." This confirms that high-priority traffic gets minimal delay (A) at the risk of starving low-priority traffic (C).

3. Stallings

W. (2014). Data and Computer Communications (10th ed.). Pearson. In Chapter 19

Section 19.2 "Resource Allocation

" the discussion on "Priority Queuing" explains that this method gives preferential treatment to high-priority packets

which are always chosen for transmission over low-priority packets. It highlights the risk of lower-priority queues being starved for service. This supports both A and C.