| The ATM Available Bit Rate (ABR) service category was initially designed to support non-real-time applications. However it is possible for ABR to support real-time applications, such as multimedia applications, by taking advantage of the inherent traffic control capability of ABR and the adaptation ability of real-time applications. Using a proper switch traffic control algorithm, ABR queues in the switches can be kept within acceptable bounds and therefore a loose end-to-end delay bound can be guaranteed. FASTRAC is a simple, scalable, provably stable, explicit rate computation scheme for flow control in computer networks. The main objective of the present thesis is to study how to transmit real-time video over ABR service using FASTRAC rate control algorithm. Using OPNET simulation tool, we study the effect of Resource Management (RM) cell interval, control delay and stability factor. With the simulation experiments, we study the performance of the rate control algorithm when it supports real-time video applications using fixed weight allocation scheme. To overcome the problems with the fixed weight allocation scheme, we introduce a dynamic weight allocation scheme, allowing us to improve the rate allocation among all ABR connections. Our simulation results also show that the spare link capacity can be further utilized by transmitting non-real-time applications without affecting the QoS of the real-time video applications. |
