A high performance OSI implementation on FDDI

The design and implementation of a high-speed, fiber-optic-based communications system which implements the critical communications technologies required for the US space station freedom program is described. The system, termed the multi-compatible network interface unit (MCNIU), prototypes a standardized communications service between intelligent devices and subsystems in the space station data management system global network. A seven-layer OSI communications solution with an integrated applications interface was developed. The functionality includes a fiber distributed data interface (FDDI) LAN at the lower layers, OSI standard protocols for the upper layers, and an application interface providing transparent network services between heterogeneous computer systems. A major technical challenge was to provide the complex standard protocols while maintaining application-level throughput. A throughput of 9.4 Mb/s delivered from application to application using checksummed connection-oriented transport class 4 service was achieved.<>