Maintaining packet order in a parallel processing network device

A plurality of packets that belong to a data flow are received and are distributed to two or more packet processing elements, wherein a packet is sent to a first packet processing element. A first instance of the packet is queued at a first packet processing element according to an order of the packet within the data flow. The first instance of the packet is caused to be transmitted when processing of the first instance is completed and the first instance of the packet is at a head of a queue at the first ordering unit. A second instance of the packet is queued at a second ordering unit. The second instance of the packet is caused to be transmitted when processing of the second instance is completed and the second instance of the packet is at a head of a queue at the second ordering unit.