Abstruet-The problem of allocating network resources to the users of an integrated services network is investigated in the context of rate-based flow control. The network is assumed to be a virtual circuiq comection-based packet network. We show that the use of Generalized processor Sharing (GPS), when combined with Leaky Bucket admission control, allows the network to make a wide range of worst-case performance guarantees on throughput and delay. The scheme is flexible in that d~erent users may be given widely different performance guarantees, and is efilcient in that each of the servers is work conserving. We present a practicat packet-by-packet service discipline, PGPS (first proposed by Deme5 Shenker, and Keshav [7] under the name of Weighted Fair Queueing), that closely approximates GPS. This altows us to relate ressdta for GPS to the packet-bypacket scheme in a precise manner. In this paper, the performance of a single-server GPS system is analyzed exactty from the standpoint of worst-case packet delay and burstiness when the sources are constrained by leaky buckets. The worst-case sewdon backlogs are also determined. In the sequel to this paper, these results are extended to arbitrary topology networks with multiple nodes. I.

While today’s computer networks support only best-effort service, future packet-switching integrated-services networks will have to support real-time communication services that allow clients to transport information with performance guarantees expressed in terms of delay, delay jitter, throughput, and loss rate. An important issue in providing guaranteed performance service is the choice of the packet service discipline at switching nodes. In this paper, we survey several service disciplines that are proposed in the literature to provide per-connection end-to-end peqormance guarantees in packet-switching networks. We describe their mechanisms, their similarities and differences, and the performance guarantees they can provide. Various issues and tradeoffs in designing service disciplines for guaranteed performance service are discussed, and a general framework for studying and comparing these disciplines are presented. I.

Motivated by recent development in high speed networks, in this paper we study two types of stability problems: (i) conditions for queueing networks that render bounded queue lengths and bounded delay for customers, and (ii) conditions for queueing networks in which the queue length distribution of a queue has an exponential tail with rate `. To answer these two types of stability problems, we introduce two new notions of traffic characterization: minimum envelope rate (MER) and minimum envelope rate with respect to `. Based on these two new notions of traffic characterization, we develop a set of rules for network operations such as superposition, input-output relation of a single queue, and routing. Specifically, we show that (i) the MER of a superposition process is less than or equal to the sum of the MER of each process, (ii) a queue is stable in the sense of bounded queue length if the MER of the input traffic is smaller than the capacity, (iii) the MER of a departure process from a stable queue is less than or equal to that of the input process (iv) the MER of a routed process from a departure process is less than or equal to the MER of the departure process multiplied by the MER of the routing process. Similar results hold for MER with respect to ` under a further assumption of independence. These rules provide a natural way to analyze feedforward networks with multiple classes of customers. For single class networks with nonfeedforward routing, we provide a new method to show that similar stability results hold for such networks under the FCFS policy. Moreover, when restricting to the family of two-state Markov modulated arrival processes, the notion of MER with respect to ` is shown to be

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.

The dramatically increased bandwidths and processing capabilities of future high-speed networks make possible many distributed real-time applications, such as sensor-based applications and multimedia services. Since these applications will have traffic characteristics and performance requirements that differ dramatically from those of current data-oriented applications, new communication network architectures and protocols will be required. In this paper we discuss the performance requirements and traffic characteristics of various real-time applications, survey recent developments in the areas of network architecture and protocols for supporting real-time services, and develop frameworks in which these, and future, research efforts can be considered.

We formulate and solve a problem of allocating resources among competing services differentiated by user traffic characteristics and maximum end-to-end delay. The solution leads to an alternative approach to service provisioning in an ATM network, in which the network offers directly for rent its bandwidth and buffers and users purchase freely resources to meet their desired quality. Users make their decisions based on their own traffic parameters and delay requirements and the network sets prices for those resources. The procedure is iterative in that the network periodically adjusts prices based on monitored user demand, and is decentralized in that only local information is needed for individual users to determine resource requests. We derive network's adjustment scheme and users' decision rule and establish their optimality. Since our approach does not require the network to know user traffic and delay parameters, it does not require traffic policing on the part of the network. 1 I...

This paper demonstrates a new, efficient, and general approach for providing end-to-end performance guarantees in integrated services networks. This is achieved by modeling a traffic source with a family of bounding interval-dependent (BIND) random variables and by using a rate-controlled service discipline inside the network. The traffic model stochastically bounds the number of bits sent over time intervals of different length. The model captures different source behavior over different time scales by making the bounding distribution an explicit function of the interval length. The service discipline, RCSP, has the priority queueing mechanisms necessary to provide performance guarantees in integrated services networks. In addition, RCSP provides the means for efficiently extending the results from a single switch to a network of arbitrary topology. These techniques are derived analytically and then demonstrated with numerical examples. 1 This research was supported by the National ...

Multicast applications, including audio and video, are expected to consume a large fraction of resources in forthcoming high speed networks. Because of this, new services are needed to provide the quality of service (QoS) required by these applications. In this paper we take a step in this direction by presenting a general framework for admission control and resource reservation for multicast sessions. Within this framework, efficient and practical algorithms that aim to efficiently utilize network resources are developed. The problem of admission control is decomposed into several subproblems that include: the division of end-to-end QoS requirements into local QoS requirements, the mapping of local QoS requirements into resource allocation, and the optimization of the resulting resource allocation for a multicast session. These are solved independently of each other yielding a set of mechanisms and policies that can be used to provide admission control and resource reservation for mul...

Leave-in-Time is a new rate-based service discipline for packet-switching nodes in a connection-oriented data network. Leave-in-Time provides sessions with upper bounds on end-to-end delay, delay jitter, buffer space requirements, and an upper bound on the probability distribution of end-to-end delays. A Leave-inTime session's guarantees are completely determined by the dynamic traffic behavior of that session, without influence from other sessions. This results in the desirable property that these guarantees are expressed as functions derivable simply from a single fixed-rate server (with rate equal to the session's reserved rate) serving only that session. Leave-in-Time has a non-work-conserving mode of operation for sessions desiring low end-to-end delay jitter. Finally, Leave-in-Time supports the notion of delay shifting, whereby the delay bounds of some sessions may be decreased at the expense of increasihg those of other sessions. We present a set of admission control algorithms which support the ability to do delay shifting in a systematic way.

We survey recent advances in theories and models for Internet Quality of Service (QoS). We start with the theory of network calculus, which lays the foundation for support of deterministic performance guarantees in networks, and illustrate its applications to integrated services, differentiated services, and streaming media playback delays. We also present mechanisms and architecture for scalable support of guaranteed services in the Internet, based on the concept of a stateless core. Methods for scalable control operations are also briefly discussed. We then turn our attention to statistical performance guarantees, and describe several new probabilistic results that can be used for a statistical dimensioning of differentiated services. Lastly, we review recent proposals and results in supporting performance guarantees in a best effort context. These include models for elastic throughput guarantees based on TCP performance modeling, techniques for some quality of service differentiation without access control, and methods that allow an application to control the performance it receives, in the absence of network support.