A buffer node and method of buffering packet data units are provided. The buffer node comprises a receive interface configured to receive a complex queue configuration and to receive packet data units, a buffer configured to implement a queue graph configuration associated with the complex queue configuration to buffer incoming packets into queues, and a send interface configured to send the dequeued incoming packets to a destination node. The queue graph configuration comprises at least one classifier configured to determine a classification type for an incoming packet, at least two queues configured to store incoming packets, and at least one dequeuer configured to select a queue from the at least two queues to be dequeued and to apply a dequeueing function on that selected queue. The method comprises a buffer node receiving a complex queue configuration from a configuration entity, receiving a plurality of packet data units from at least one the packet source node, and sending each incoming packet to one of the at least two queues based on the queue graph configuration. The complex queue configuration is associated with a queue graph configuration for buffering packet data units.