A communication node comprises a receiver for receiving packets and a routing device for routing the received packets to one of two output ports. For each output port, the communication node further comprises a classifier for classifying a received packet based on its traffic characteristic and storing that packet in a corresponding queue for that traffic characteristic, and a concatenated packets preparer for concatenating n received packets from each queue to form a concatenated packet to be transmitted by the associated output port, where the maximum of n is determined based on the traffic characteristic of the associated queue.