Which QoS function uses the IP Precedence bits in the IP ToS field to separate traffic into priority levels?

Marking is the QoS function that modifies the ToS (Type of Service) field in the IP header, specifically using bits like IP Precedence or DSCP (Differentiated Services Code Point), to assign a priority level to traffic. This priority information is then used by subsequent network devices for appropriate queuing, scheduling, and congestion management. Shaping and policing are congestion management tools that control traffic rates, but they don't modify the packet header's priority bits. Classification is the process of identifying and categorizing traffic, which often precedes marking, but classification itself doesn't alter the packet header.