Which per-hop traffic-control feature does an ISP implement to mitigate the potential negative effects of a customer exceeding its committed bandwidth?

Policing is a per-hop traffic-control feature where an ISP can drop or re-mark (e.g., set to a lower priority) traffic that exceeds a configured rate. This directly mitigates the negative effects of a customer exceeding their committed bandwidth by immediately enforcing the contract limits.

Queuing involves buffering and prioritizing packets that cannot be sent immediately, which handles congestion but doesn't directly enforce committed bandwidth limits by dropping or re-marking excess traffic.

Marking changes a packet's header to indicate its class of service, but it doesn't enforce bandwidth limits itself; it relies on other QoS mechanisms like policing or queuing to act on those marks.

Shaping buffers excess traffic and sends it out later, which smooths traffic bursts but does not drop excess traffic or enforce strict limits like policing, which is what an ISP would use for contractual bandwidth enforcement.