Congestion control is always an active research field for guaranteeing the Quality of Services (QoS) of datacenter networks (DCNs). However, the current end-to-end TCP design enables both senders and receivers not to directly and precisely obtain the congestion information, incurring inaccurate or non-real-time adjustments. Moreover, switches that act as fundamental primitives in DCN are usually used for reactive congestion feedbacks (e.g., Ack and ECN), leading to underused for proactive congestion control. In this article, we propose a novel active queue management (AQM) scheme called Active Buffer Queueing (ABQ) which leverages active buffer queueing of DCN switches to achieve both high-throughput and loss-free transmissions. When the traffic pattern in DCN is changed intensely in flow size, number and interval, the feedback information to TCP end hosts are imprecise. Unlike other AQMs, the key idea of ABQ is to adjust the flow rate (or packet pace) directly in the switch according to the real-time congestion state. We explain the design rationale behind ABQ and present simulation results of its performance. Finally, we discuss the implementation on the NetFPGA.