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To achieve satisfying user experiences of diverse applications, quality of service (QoS) guaranteed mechanisms such as per-flow queuing are required in routers. However, deployment of per-flow queuing in high-speed routers is considered as a great challenge since its industrial brute-force implementation is not scalable with the increase of the number of flows. In this study, the authors propose a dynamic queue sharing (DQS) mechanism to enable scalable per-flow queuing. DQS keeps isolation of each concurrent active flow by sharing a small number of queues instead of maintaining a dedicated queue for each in-progress flow, which is novel compared to the existing methods. According to DQS, a physical queue is created and assigned to an active flow upon the arrival of its first packet, and is destroyed upon the departure of the last packet in the queue. The authors combine hash method with binary sorting tree to construct and manage the dynamic mapping between active flows and physical queues, which significantly reduces the number of required physical queues from millions to hundreds and makes per-flow queuing feasible for high-performance routers.