Network and end-host support for heterogenous services in the Internet

The rapid growth of the Internet has been accompanied by an evolution of new applications, ranging from simple data services to complex applications such as IP telephony, video on demand, and interactive multimedia communication. These new applications require an end-to-end IP architecture that can support multiple levels of service while preserving the scalability and simplicity of the current so-called “best-effort” Internet service model. This dissertation examines and proposes network and end-host support for these cutting-edge applications accounting for both the heterogeneity in the service requirements and the scalability concern. In the first part of this dissertation, we focus on the end-host and propose solutions for handling the variable resource requirements of multimedia streaming applications. We show that commonly-used round-based scheduling techniques for transferring data between the disk and the network interface are not well suited for the retrieval of multimedia streams. We propose lazy-EDF scheduling and show that it minimizes the server buffer and disk bandwidth requirements for a static set of requests. Simulation studies with MPEG traces demonstrate the significant performance gains possible under lazy-EDF. Using the optimality properties of lazy-EDF, we next propose greedy-fill with lazy discard (GFD) scheduling to address dynamic request arrivals and admission control in a disk subsystem. In addition, we propose efficient workload description for stored VBR video that we demonstrate to increase the resource utilization as high as 200–250% over the best known result. In the second part of this dissertation, we focus on scalable network support for providing different classes of services to multimedia applications. In particular, we focus on the achievable services and limitations of the recently proposed differentiated services (diffserv) architecture in which simple mechanisms are used within the network core and more complicated functionality is possible only at the network edge. First we determine the mechanisms at the network core that are best suited to provide service differentiation. In order to do so, we compare the ability of proposed diffserv mechanisms in providing delay and loss differentiation across service classes. Next we examine the impact of diffserv mechanisms on the applications that use TCP congestion control protocol. We present a simple and yet accurate analytical model for TCP when “profile-based” marking is used at the network edge for providing service differentiation. Using this model, we examine whether it is possible to provide rate guarantees to TCP flows by solely setting the profile parameters at the network edge. We find that it is not always easy to regulate or guarantee the rate achieved by a TCP flow using this approach. We derive conditions that determine what rates are achievable and provide insights for choosing appropriate profile parameters for these achievable services. These observations are validated in a testbed implementation using PCs running modified Linux kernel