The disclosed embodiments relate to a system for communicating packets through a network switch fabric. During operation, at an aggregation point in the network switch fabric, the system segregates packet flows from multiple sources into a set of quality-of-service (QoS) buckets. Next, the system monitors traffic rates for each QoS bucket. The system then determines a state for each QoS bucket by comparing a traffic rate for the QoS bucket with one or more state-specific thresholds. When a packet is subsequently received for a given QoS bucket, the system performs an action based on a state of the given QoS bucket.