A network device includes an input interface, at least one processing path and an output interface. The input interface receives data units on a plurality of streams and assigns a first sequence number to each of the received data units. The at least one processing path performs a route look-up for each of the data units, where the route look-up determines a routing destination for a respective data unit. The output interface assigns a second sequence number to each of the processed data units based on a number of memory references associated with the route look-up for each of the data units and re-orders the processed data units based on the second sequence number assigned to each of the processed data units.