D³ is a deadline-aware control protocol that is customized for the datacenter environment. D³ uses explicit rate control to apportion bandwidth according to flow deadlines. Evaluation from a 19-node, two-tier datacenter testbed shows that D³, even without any deadline information, easily outperforms TCP in terms of short flow latency and burst tolerance. Further, by utilizing deadline information, D³ effectively doubles the peak load that the datacenter network can support.