A packet communication apparatus comprising a node management processor for controlling the whole apparatus, network interfaces for transmitting and receiving packets to and from external networks, function enhancement modules for performing predetermined processes on the packets, and a switch for transferring the packets within the apparatus. The network interface includes a CPU and a memory, the memory stores a program executed by the CPU, the CPU processes the packet received from the external networks by executing the program, and the function enhancement module stores the program stored in the memory.