Performance Analysis of a Differentiated Service Router Guidance

The current Internet provides only the best-effort service, which is unable to offer quality of service (QoS) guarantees. Recently, in order to offer QoS guarantees for multimedia applica-tions such as real-time applications, Integrated Service (IntServ) was proposed. The IntServ is based on reservation to provide the end-to-end QoS guarantees per flow. The mechanism is implemented by a signaling protocol known as RSVP. The IntServ has a number of attractive features. However, its implementation has several drawbacks such as a scalability problem. More recently, Differentiated Service (DiffServ) was proposed as a scalable low-cost architec-ture to solve the problems in the IntServ. In the DiffServ, all flows are divided into several classes and flows in each class are aggregated. The DiffServ then provides QoS guarantees for the aggregated flows. However, it is not clear about performance the DiffServ provide for each class. Thus, quantifying such performance is very important to understand the benefits and drawbacks of the scheme. Our goal in this thesis is to examine QoS performance quantitatively. For this purpose, we consider a Differentiated Service router model with four classes in terms of a nonpreemptive priority M/G/1 queue with repeated vacations. Packets of the first three classes are accommodated in their dedicated waiting room with finite capacity, and vacations represent services of packets with the lowest priority. The router is operated under the RIO (RED with in and out packets). For this model, The marginal queue length distribution is analyzed by constructing an embedded Markov chain. We obtain expressions for performance measures that characterize the different levels of the service such as throughput and average delay. Further, we propose a way to determine RIO parameters. In numerical experiments, we demonstrate that our proposed scheme works well to offer strict QoS guarantees for respective classes. Content