According to embodiments of the invention, there is provided a method for operating a network processor. The network processor receiving a first data packet in a stream of data packets and a set of receive-queues adapted to store receive data packets. The network processor processing the first data packet by reading a flow identification in the first data packet; determining a quality of service for the first data packet; mapping the flow identification and the quality of service into an index for selecting a first receive-queue for routing the first data packet; and utilizing the index to route the first data packet to the first receive-queue.