This paper considers the support of real-time applications in an

The Internet has been a startling and dramatic success. However, multimedia applications, with their novel traffic characteristics and service requirements, pose an interesting challenge to the technical foundations of the Internet. In this paper we address some of the fundamental architectural design issues facing the future Internet. In particular, we discuss whether the Internet should adopt a new service model, how this service model should be invoked, and whether this service model should include admission control. These architectural issues are discussed in a nonrigorous manner, through the use of a utility function formulation and some simple models. While we do advocate some design choices over others, the main purpose here is to provide a framework for discussing the various architectural alternatives.

Over the past several years there has been a considerable amount of research within the field of quality of service (QoS) support for distributed multimedia systems. To date, most of the work has been within the context of individual architectural layers such as the distributed system platform, operating system, transport subsystem and network. Much less progress has been made in addressing the issue of overall end-to-end support for multimedia communications. In recognition of this, a number of research teams have proposed the development of QoS architectures which incorporate quality of service configurable interfaces and quality of service driven control and management mechanisms across all architectural layers. This paper examines the state-of-the-art in the development of QoS architectures. The approach taken is to present QoS terminology and a generalised QoS framework for understanding and discussing quality of service in the context of distributed multimedia systems. Following this, we evaluate a number of QoS architectures that have emerged in the literature. 1.

In this paper we identify the challenges and open issues involved in providing quality-of-service (QOS) guarantees to sessions in a high-speed wide area network and briefly survey research in this area. Four approaches towards providing QOS guarantees are described and discussed: the tightly controlled approach, the approximate approach, the bounding approach, and the observation-based approach.

In this paper, we develop bounds on the individual session backlog and delay distribution under the Generalized Processor Sharing (GPS) scheduling discipline . This work is motivated by, and is an extension of, Parekh and Gallager 's deterministic study of the GPS scheduling discipline with leaky-bucket token controlled sessions [15], [16]. Using the exponentially bounded burstiness (E.B.B.) process model introduced in [18] as a source traffic characterization, we establish results that extend the deterministic study of GPS: for a single GPS server in isolation, we present statistical bounds on the distributions of backlog and delay for each session. In the network setting, we show that networks belonging to a broad class of GPS assignments, the socalled Consistent Relative Session Treatment (CRST) GPS assignments, are stable in a stochastic sense. In particular, we establish simple bounds on the distribution of backlog and delay for each session in a Rate Proportional Processor Sharin...

Integrated Services Packet Networks (ISPN) are designed to integrate the network service requirements of a wide variety of computer-based applications. Some of these services are delivered primarily through the packet scheduling algorithms used in the network switches. This paper addresses two questions related to these scheduling algorithms. The first question is: what scheduling services should an ISPN offer? In answer, we propose a scheduling service model for ISPN's which is based on our projections about future application and institutional service requirements. Our service model includes both a delay-related component designed to meet the ergonomic requirements of individual applications, and also a hierarchical link-sharing component designed to meet the economic needs of resource sharing between different entities. The second question we address is: what implications does this service model have for the packet scheduling algorithms? We answer this question by construc...

This paper addresses the integration of services in the Internet and the resulting impact on pricing policies. I first address why an integrated services Internet is desirable, and give an overview of the services it is likely to offer. I then argue that an integrated services Internet, in order to be efficient, must employ per-user, quality-ofservice sensitive, and usage-based pricing policies. 1 Introduction In the next five years, the Internet will undergo significant technical changes. These will probably include dramatic increases in bandwidth 1 on the backbone transmission links, better physical access from homes and businesses, and a more sophisticated network architecture. Internet policies are also likely to change; these policy changes will probably include allowing more public access, increasing privatization of service provision, reduced or at least modified government subsidies, and new pricing schemes. These policy and technical changes will reinforce each other: some...

The Internet is currently being confronted with service demands from a new generation of applications. Supporting these applications effectively and efficiently will require extending the current Internet "best-effort" service model to one that offers an integrated suite of services. The purpose of this memo (which is derived primarily from [34]) is to describe a proposed "core" service model for an integrated services Internet. In the Appendix we discuss the process by which such a service model could be standardized by the Internet.

The goal of network design is to meet the needs of resident applications in an efficient manner. Adding real-time service and point-to-multipoint multicast routing to the Internet 's traditional point-to-point best effort service model will greatly increase the Internet's efficiency in handling point-to-multipoint real-time applications. Recently, the RSVP resource reservation protocol has introduced the concept of "reservation styles", which control how reservations are aggregated in multipoint-to-multipoint real-time applications. In this paper, which is an extension of [9], we analytically evaluate the efficiency gains offered by this new paradigm on three simple network topologies: linear, m-tree, and star. We compare the resource utilization of more traditional reservation approaches to the RSVP reservation styles in the asymptotic limit of large multipoint applications. We find that in several cases the efficiency improvements scale linearly in the number of hosts.

We introduce a new scheduling algorithm for multimedia traffic, using capacity reservation. We compare it to other algorithms in the literature. It has been implemented and its worst-case performance analysed. It appears to give a noticeably improved quality of service to delay-sensitive traffic. 1 Introduction Networked multimedia applications are becoming increasingly important to the business community, and an increasing proportion of the traffic of data networks is used by such applications. Multimedia traffic has different quality of service needs than those provided by most routers, which were designed with regular data traffic in mind. Multimedia traffic is much more sensitive to delay than regular data traffic [20]. Current routing technology gives "best-effort" service, aimed at maximizing throughput, with minor consideration to delay and loss. As a result, some delay-sensitive packets are not delivered in time. We therefore believe that it is worth using a router schedulin...