Methods and systems for preemption in a network having a core device with at least one egress interface are disclosed. In one embodiment, the method includes performing flow-based hash utilizing a plurality of hash-buckets each set to a first state or a second state and computing a load based on a rate measurement that excludes flows which hash into hash-buckets having a state set to the second state. The computed load is compared to a preemption threshold and if the computed load exceeds the preemption threshold, the state of at least one of the hash-buckets is changed from the first state to the second state. An action, such as dropping all packets or marking all packets, is performed on flows hashing in a hash-bucket in the second state.