A network device for processing data on a data network includes a port interface, in communication with a plurality of ports, configured to receive data packets from a data network and to send processed data packets to the data network, a memory management unit, in communication with and controlling memory, configured store data on and retrieve data from the memory and a parser, in communication with the port interface and the memory management unit, configured to parse the received data packets to determine attributes of the data packets and to modify data packets retrieved from the memory, based on the determined attributes, to produce the processed data packets. The parser is configured to modify the data packet on a cell basis, through addition, subtraction and substitution of cells of the data packets, where each cell of the cells has a predetermined bit-length.