OSI Communication Services in a Heterogeneous Environment

An experimental OSI transport service for a heterogeneous distributed environment based on interconnected local-area networks has been developed as a joint project between the University of Karlsruhe and the IBM Zurich Research Laboratory. The objectives of this effort were twofold: 1.Provide a reliable and efficient communication base for resource sharing and distributed applications, and2.develop in-depth understanding of the issues important to implementation and operation of OSI protocols in such an environment. The transport service facilitates communication among IBM S/370s, IBM PCs, and DEC VAXs. A network-level Interworking Unit has been developed to interconnect the IBM Token Ring, Ethernet, and X.25 subnetworks. In the associated research projects, the performance of the transport service and the impact of internetworking have been studied both experimentally and via simulation. A comprehensive set of test tools has been developed and applied to test the compatibility of the different implementations of the transport service.