350-401 Question 58
Single answerA network administrator is troubleshooting a QoS implementation for a corporate network. The wired network uses a priority queuing policy to ensure voice traffic is prioritized over web traffic. However, users report degraded voice quality during peak usage times. Upon inspecting the configuration, the administrator finds the following commands on an interface:
interface GigabitEthernet0/1 service-policy output VOICE-PRIORITY
policy-map VOICE-PRIORITY class VOICE priority 1000 class WEB bandwidth 500
What could be the issue with the current configuration?
- A
The priority queue for the VOICE class does not have a policing mechanism configured.
- B
The bandwidth allocated to the WEB class is too high, leaving insufficient bandwidth for the VOICE class.
- C
The priority command in the VOICE class is misconfigured and should use the 'bandwidth' command instead.
- D
The service-policy is applied to the wrong interface direction and should be applied in the input direction.
Show answer and explanation
Correct answer: A
Explanation
The issue lies with the lack of a policing mechanism for the priority queue handling the VOICE class. Without policing, the priority queue can monopolize the interface bandwidth during congestion, leading to degraded performance for other traffic. Adding a policing mechanism to the VOICE class would ensure fair bandwidth distribution while still prioritizing latency-sensitive traffic.
- A. Correct.
The priority command in QoS enables strict priority queuing, but without a policing mechanism, it can starve other traffic classes of bandwidth during congestion. This is likely causing the reported issue.
- B. Incorrect.
The bandwidth allocation for the WEB class is irrelevant in this case because the priority queue for the VOICE class will always be serviced first during congestion unless explicitly policed.
- C. Incorrect.
The priority command is correctly used for the VOICE class since it is appropriate for latency-sensitive traffic like voice. The 'bandwidth' command would not provide the necessary strict prioritization.
- D. Incorrect.
The service-policy is correctly applied in the output direction, as QoS policies for egress traffic are typically applied to manage traffic leaving the interface.