This research aims at applying high-speed digital communication and switching technologies to computer systems. Typical applications to be considered includes interconnection of processor subsystems among themselves for multiprocessor configurations, and the interconnection of processors to I/O subsystems. These applications require high bandwidth, low latency, and low error- rate beyond the capability of current electrical buses and O/I channels. It studies the applicability of various high-speed interconnection technologies and the development of new architectures and protocols suitable in a computer system environment. It uses fiber-optics as the link technology and high-speed crossbar switches for interconnection. The structure of these switches, as well as mechanisms for connection setup, routing, and flow-control across multiple cascaded switches are studied. In addition, fast connection setup within a switch by the use of multiple controllers are also investigated. Alternate interconnection technologies such as optical subcarrier multiplexing are also investigated as low- cost replacements for the switch. Experimental evaluation of the concepts is performed on a testbed consisting of IBM RS/6000 AND PS/2 high-performance workstations equipped with 100 Mbits/s optical link cards