When the propagation delay becomes zero, the unslotted CSMA/CD protocol with retransmission control policy is reduced to a retrial queueing system with retrial rate control policyl. In this thesis we give an analytical results for M/M/c retrial queue with retrial rate control policy. We analyze the performance of this model such as steady state probability, blocking probability and mean waiting time of a customer by using matrix-geometric method and C-programming. Also, as a variation, we deal with a loss model.