CPU transmission of unmodified packets

A network device for processing packet. The network device includes an ingress module for performing switching functionality on an incoming packet, wherein the network device determines a destination port to which the incoming packet is to be transmitted. The network device also includes a CPU processing module for transmitting information between the network device and an external CPU. The external CPU transmits a formatted packet to the network device through the CPU processing module. The formatted packet includes module header and a data field. The ingress module uses information in a start field of the module header to determine that the incoming packet is a formatted packet and generates instructions for notifying other modules of the network device that the formatted packet is not to be modified by the network device and determines that the formatted packet is to be transmitted to a destination field in the formatted packet.