Packet scheduling with delay and loss differentiation

To support quality of service over the Internet, the Differentiated Services model has been proposed recently by the IETF. In the Differentiated Services model, ¤ows with similar QoS requirements are aggregated into classes in order to counter the scalability problem faced by the Integrated Services model. There have been several models proposed for service differentiation. The relative differentiated service model is one among them in which an assurance is given that “higher classes will be better, or at least no worse, than lower classes.” Packet delay and packet loss are two general quality metrics under which the differentiation can take place. In this paper, we propose three schedulers based on the relative differentiated service model, namely, delay only, loss only, and both delay and loss schedulers. To evaluate the performance of the proposed schedulers, we have conducted extensive simulation studies (both per-hop and end-to-end) under uniform and nonuniform traf£c loads. Our simulation studies show that the delay only and loss only schedulers differentiate effectively only in delay and loss, respectively, and the combined delay and loss scheduler differentiates effectively in both delay and loss.