Which mechanism is used to shape traffic by delaying packets to meet a rate before sending them?

• A. Policing
• B. Queueing
• C. Shaping
• D. Marking

Answer: (C)

Shaping smooths traffic by delaying packets so they conform to a defined outbound rate before they are transmitted. It uses a buffering mechanism and a timer to control when each packet can be sent, spreading out bursts so the actual transmission rate matches the configured limit. This deliberate delay before sending is what distinguishes shaping from other mechanisms.

Why this is the best fit: the key idea is shaping the flow by introducing delays to meet a target rate, effectively smoothing traffic to prevent bursts from propagating downstream. Policing, on the other hand, enforces the rate by dropping or re-marking packets that exceed the limit, rather than delaying them to fit the rate. Queueing involves buffering to manage temporary congestion but does not inherently enforce a fixed transmission rate by delaying packets to meet that rate. Marking changes packet treatment (like DSCP/CoS) but doesn't control timing or rate.

In practice, shaping provides a controlled, rate-limited output by queuing and scheduling transmissions at the desired pace, which is exactly the mechanism described.