First, I would like to thank my advisor Dr. Daniel A. Reed, for providing the patience, time, guidance, and equipment without which this work would not have been possible. Thanks to Dirk Grunwald for sharing his knowledge on load balanceing to get me started on this work and for providing Awesime on top of which ths simulator was built. Thanks also to dave bradley for providing iPSC/1 benchmark data and frequent help with LATEX, to Mark Hartman for helping with the network simulator development, to Dave Rudolph for providing logging data on the Simplex program, and to Betty Cheng for her LATEX thesis macros. Finallyk my sincere gratitude and appreaciation to my mother and my brother for their endless support and for being there when I needed them. This work was supported in part by the National Science Foundation under grants NSF CCR 86057696, NSF CCR 87096653 and NSF ANTI TAPESTRY 1-5-30035, by the Naitoal Aeronautics and Space Administration under NASA Contract Number NAG-1-613,by the Air Force Office of Scientific Research under grant AFOSR-F49620-86-C-0136(URI), by the METNET grant from AT&T, and by an equipment donationform Digital Equipment corporation.