Simulation Model of a CSMA/CD Bus Local Area Network with Multiple Variables

摘要

Numerous statistical studies of the expected performance of a CSMA/CD bus local area network (LAN) have been completed. With the statistical approach; the number of input sources is normally limited. Also, input sources normally possess the same statistical parameters with respect to input rate and the amount of data per input. This thesis develops a CSMA/CD bus LAN simulation which can handle up to 500 input sources, all with a different input rate and amount of data per input. The limitation of 500 is due only to the fact that the simulation model was implemented on a 128K memory micro-computer. The model takes the approach that once an input is made, the time for the input to travel through the various stages of a network can be easily calculated. Therefore, the simulation model generates traffic based on the statistical parameters of each individual source, then tracks the input as the simulation clock ticks. Using the memory power of the computer to keep track of the location of all inputs, the simulation model is able to determine the effect of an input on all other inputs. In some cases, an input has no direct effect on other inputs, and at the other extreme, when inputs want to use the bus at the same time, they have a drastic on each others performance. Numerous tests were performed to demonstrate the ability of the simulation model to model a CSMA/CD bus LAN.