Communication device for processing outgoing and incoming packets. The device includes a plurality of signal processing units connected in sequence, each signal processing unit being clocked by a common clock signal. The device further includes a mode line connected to each signal processing unit for switching each signal processing unit between a transmit mode and a receive mode. The device further includes a control line to which each signal processing unit is connected. The control line communicating flow control information either in the transmit mode to at least one of the preceding signal processing units or in the receive mode to at least one of the following signal processing units.