What does traffic shaping do to reduce congestion in a network?

Traffic shaping functions by buffering excess packets that exceed a configured rate and then queuing them for later transmission at a controlled, sustained rate. This process smooths out traffic bursts, preventing immediate packet drops and reducing congestion by ensuring that traffic adheres to specified bandwidth limits over time.

Buffering without queuing packets would just hold them briefly without actively managing their transmission order or rate to shape traffic.

Queuing packets without buffering them would mean packets exceeding the rate would be immediately dropped if the queue is full, rather than being held and smoothed out.

Dropping packets is a characteristic of traffic policing, which discards excess traffic immediately, whereas traffic shaping aims to smooth traffic by buffering and delaying it, not dropping it.