Abstract: A system for transmitting data packets includes a memory that stores buffer descriptor (BD) rings, packet en-queuing and de-queuing modules, and a network controller. The packet en-queuing module en-queues a first data packet into a first BD ring based on a first priority value of the first data packet and a first set of quality-of-service (QoS) rules. The packet de-queuing module de-queues a second data packet from a second BD ring based on a second set of quality-of-service (QoS) rules and indicates to the network controller that the second data packet is ready for transmission from the second BD ring.