200-301 Question 384
Select 2An enterprise network administrator wants to prioritize voice traffic over web browsing traffic to ensure better call quality. Which two actions are necessary at each router hop along the path to achieve this using forwarding per-hop behavior (PHB) for QoS?
- A
Classify traffic based on application type or protocol
- B
Mark packets with appropriate Differentiated Services Code Point (DSCP) values
- C
Encrypt traffic to protect data integrity during transit
- D
Drop packets based on random early detection (RED) to control congestion
- E
Apply priority queuing to ensure voice traffic is transmitted with low latency
Show answer and explanation
Correct answers: A, B
Explanation
To achieve traffic prioritization with forwarding per-hop behavior (PHB) for QoS, traffic must first be classified based on criteria like application or protocol type. Once classified, packets should be marked with DSCP values so each router along the path can recognize and prioritize the traffic class appropriately. These steps enable consistent QoS treatment across the network.
- A. Correct.
Classifying traffic assigns packets to categories based on application type, protocol, or other criteria, enabling QoS mechanisms to differentiate traffic and apply specific treatments.
- B. Correct.
Marking packets with DSCP values allows routers and switches to identify the traffic class and prioritize handling based on its importance, such as prioritizing voice over web traffic.
- C. Incorrect.
Encrypting traffic is related to security rather than QoS and does not contribute to applying per-hop behavior for traffic prioritization.
- D. Incorrect.
Dropping packets using RED is a congestion avoidance mechanism, not a method for prioritizing traffic for QoS.
- E. Incorrect.
While priority queuing is a valid QoS mechanism, it is applied after traffic classification and marking, and the question asks about actions necessary at each hop along the path.