A method and apparatus for flexibly interconnecting the nodes (9, 10, n) of a local data network to achieve reliable internodal data transmission while minimizing the extra data processing load on the host processors of each node. An interface processor (100) is provided at each node which controls transmission and reception of data packets and the communication of data from and to the location in node storage associated with the program processes which generate and receive the data. Different protocols are provided for different types of messages and are controlled by the interface processor in order to provide high reliability data transmission where needed. Destination addresses are associated with each data packet to provide flexible routing of data.