Calculating te maximum mean data rate in local area networks

In February 1980 a group of people met in San Francisco, CA, USA, to form Project 802: Local Area Network Standards, sponsored by the IEEE Computer Society. The subcommittee held two open meetings, each followed by circulation of a draft report for comment. All claims had to have enough evidence to allow independent verification. Such evidence included source code plus data for all simulation results, all numbers and formulas for analytic results, and complete experimental conditions and measurement procedures for data analysis on actual systems. This article summarizes the subcommittee's focus on calculating the maximum mean data rate. The best available evidence, based on this study and related studies, is as follows. Token passing via a ring is the least sensitive to workload, offers short delay under light load, and offers controlled delay under heavy load. Token passing via a bus has the greatest delay under light load, cannot carry as much traffic as a ring under heavy load, and is quite sensitive to the bus length (through the propagation time for energy to traverse the bus). Carrier sense collision detection offers the shortest delay under light load, is quite sensitive under heavy load to the workload, and is sensitive to the bus length (the shorter the bus the better it performs) and to message length (the longer the packet the better it does). While this evidence is currently being examined by those actually building local area networks, other independent testing of these plots for confirmation is sought and encouraged.