Efficient Marking Techniques for Differentiated Services in the Internet

Michigan State University, East Lansing MI

Investigators

Abstract

The best-effort service model of the current generation Internet is not adequate for evolving and expanding applications such as continuous media, real-time applications, and e-commerce environments. These applications require certain quality of service (QoS) assurance that could be provided through service discrimination in the Internet. Differentiated Services (DiffServ) have been proposed as a viable solution for providing service differentiation in the Internet. DiffServ operates on the aggregate traffic on a per-hop basis and thus avoids the scalability problems associated with the integrated service model. A major component of the DiffServ architecture is the markers that mark packets based on the service level agreements between adjacent Internet domains (interdomain makers) or between the end node and its ver first domain (leaf markers). The Internet core routers route packets discriminatley based on their marking. Thus the marking technique affects the performance of DiffServ significantly. This proposal focusses on the design and implementation of efficient marking techniques for differentiated services in the Internet. The proposed research targets the marking issues at both the interdomain markers and the leaf markers. Our ongoing effort on the marking scheme for interdomain marker addresses random and early demotion and promotion of packets to improve the bandwidth utilization while maintaining fairness between different flows. This approach employs a three-color marking scheme and uses a modified leaky bucket technique for flow control. A detailed performance study, impact of various parameters, usage of multiple precedence levels, and flow control techniques will be investigated using the ns simulator. In the context of leaf markers, we propose to integrate the marking scheme with the TCP layer at the end nodes. Thus in addition to the aggregte level flow control at the interdomain layer, we will also achieve some degree of flow-level service differentiation. Our approach is based on splitting the TCP congestion window logically on the basis of the desired levels of services. During congestion, the splits of the congestion window gets affected corresponding to their relative service level agreements. Such an approach would also make the flow control fair across multiple flows with different service level agreements. Maintenance of proportional fairness has been observed as a difficult task in several prior research. We propose to evaluate the impact of the proposed leaf marker through an experimental implementation. The outcome of the proposed research will have a broader impact on the Internet infrastructure and on its users. Specifically, the proposed techniques will improve the bandwidth utilization in the Internet while providing differentiated services. At the local level, the research will have a positive educational impact on the students of Michigan State University.