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…

Policing is applied at the ingress to enforce the committed rate for the EF class by dropping or re-marking packets that exceed the contracted rate. Unlike shaping, policing does not buffer excess traffic, which is critical for EF/VoIP because buffering introduces queuing delay and jitter that violates the low-latency guarantees EF requires.

Shaping buffers excess traffic to smooth the output rate, which introduces queuing delay and jitter - unacceptable for real-time VoIP traffic classified as EF.

WRED is a congestion-avoidance mechanism designed for TCP flows that can tolerate random drops, not for the EF class which demands strict low-loss, low-latency treatment.

CB-WFQ is an egress scheduling tool that allocates bandwidth among classes in a queue; it is not an ingress traffic conditioning or policing mechanism.