Electrical and Computer Engineering Department-College of Engineering-Sultan Qaboos University Performance of Copy Network in ATM Switch Al Qasim Mohammed AL Khalili Abstract In this thesis we are trying to simulate an ATM switch in order to enhance the performance of the switch in multicast. The switch is multistage with buffers at the input as well as the output.A proposed device is called a Copy Network is to be attached at the inputs of this switch and simulation takes place on the same set of data for both the typical switch and for the new suggested device for comparison. One of the major performance criteria is number of lost cells, and how both of the systems behave on different scenarios that was tried to be as close as possible to reality. The subject and results of this thesis were discussed in the 6th World Multicorference on Systemics, Cybernetics and Informatics (SCI 2002), Orlando, USA, July 1418,2002[1].