CCDE: Cisco Certified Design Expert (Written) — Question 20

A service provider is offering a QoS-based transport service. Three classes have been defined in the core, including an Expedited Forwarding (EF) class for VoIP traffic. Which tool should be used at the ingress for the EF class?

Answer options

• A. policing
• B. shaping
• C. WRED
• D. CB-WFQ

Correct answer: A

Explanation

Policing is the correct tool to manage the EF class at ingress, as it ensures that traffic conforms to specified rates and can drop excess packets, which is crucial for maintaining QoS for VoIP. Shaping, on the other hand, is used for smoothing traffic bursts rather than enforcing strict limits. WRED (Weighted Random Early Detection) is a queue management technique that helps in congestion avoidance but is not specifically used at ingress. CB-WFQ (Class-Based Weighted Fair Queuing) is a queuing method that schedules packets but does not control the rate of incoming traffic like policing does.