In a multinode data processing system in which the nodes communicate with one another through communication adapters coupled to a switch or network, a method is provided for using the Internet Protocol (IP) for transmitting large broadcast data packets without incurring the overhead normally associated with packet fragmentation. By adding an Internet Protocol (IP) header as the first header in every packet fragment in the fragmentation process, fragmented packets are able to be assembled in the IP layer without intervention at the adapter interface layer.