This paper is principally concerned with resource allocation for connections tolerating statistical qualityof service #QoS# guarantees in a public wide-area ATM network. Our aim is to sketch a framework, based on e#ective bandwidths, for call admission schemes that are sensitivetoindividual QoS requirements and account for statistical multiplexing. We begin by describing recent results approximating the e#ective bandwidth required by heterogeneous streams sharing bu#ered links, including results for the packetized generalized processor sharing service discipline. Extensions to networks follow via the concept of decoupling bandwidths - motivated by a study of the input-output properties of queues. Based on these results we claim that networks with su#cient routing diversity will inherently satisfy nodal decoupling. We then discuss on-line methods for estimating the e#ective bandwidth of a connection. Using this type of tra#c monitoring we propose an approach to usage parameter ...

The efficient distribution of stored information has become a major concern in the Internet which has increasingly become a vehicle for the transport of stored video. Because of the highly heterogeneous access to the Internet, researchers and engineers have argued for layered encoded video. In this paper we investigate delivering layered encoded video using caches. Based on the stochastic knapsack theory we develop a model for the layered video caching problem. We propose heuristics to determine which videos and which layers in the videos should be cached in order to maximize the revenue from the streaming service. We evaluate the performance of our heuristics through extensive numerical experiments. We find that for typical scenarios, the revenue increases nearly logarithmically with the cache size and linearly with the link bandwidth that connects the cache to the origin servers. We also consider service models with request queuing and negotiations about the delivered stream quality and find that both extensions provide only small revenue increases.

Over the last few years, a substantial number of call admission control (CAC) schemes have been proposed for ATM networks. In this article, we review the salient features of some of these algorithms. Also, we quantitatively compare the performance of three of these schemes.

We consider large buffer asymptotics for feed-forward networks of discrete-time queues with deterministic service rate shared by multiple classes of streams subject to work conserving service policies. First we review the concept of effective bandwidths for traffic streams sharing a common buffer subject to subject to tail constraints on the workload distribution. Next, we obtain the effective bandwidth of the departure process from such a queue, proving that in fact the effective bandwidth of the output is at worst equal to that of the input, and depending on the service rate, strictly less than that of the input. We then define the notion of a decoupling bandwidth and the associated constraints, guaranteeing that asymptotics within the network are decoupled. These results provide a framework for call admission schemes which are sensitive to constraints on the tail distribution of the workload or approximate cell loss probabilities. Our results require relatively weak assumptions on both the traffic streams and service policies. We consider the problem of “optimal ” traffic shaping (via buffering) subject to a loss constraint. Finally, we discuss our results in the context of resource management for ATM networks. 1

Current solutions to providing statistical performance guarantees to bursty traffic such as compressed video encounter several problems: 1) source traffic descriptors are often too simple to capture the burstiness and important time-correlations of VBR sources or too complex to be used for admission control algorithms; 2) stochastic descriptions of a source are inherently difficult for the network to enforce or police; 3) multiplexing inside the network's queues may change the stochastic properties of the source in an intractable way, precluding the provision of end-toend QoS guarantees to heterogeneous sources with different performance requirements. In this paper, we present a new approach to providing end-to-end statistical performance guarantees that overcomes these limitations. We term the approach Hybrid Bounding Interval Dependent (H-BIND) because it uses the Deterministic-BIND traffic model to capture the correlation structure and burstiness properties of a stream; but unlike a...

We consider the efficient estimation, via simulation, of very low buffer overflow probabilities in certain acyclic ATM queueing networks. We apply the theory of effective bandwidths and Markov additive processes to derive an asymptotically optimal simulation scheme for estimating such probabilities for a single queue with multiple independent sources, each of which may be either a Markov modulated process or an autoregressive processes. This result extends earlier work on queues with either independent arrivals or with a single Markov modulated arrival source. The results are then extended to estimating loss probabilities for intree networks of such queues. Experimental results show that the method can provide many orders of magnitude reduction in variance in complex queueing systems that are not amenable to analysis.

As a model for an ATM switch we consider the overflow frequency of a queue that is served at a constant rate and in which the arrival process is the superposition of N traffic streams. We consider an asymptotic as N !1 in which the service rate Nc and buffer size Nb also increase linearly in N . In this regime, the frequency of buffer overflow is approximately exp(\GammaN I(c; b)), where I(c; b) is given by the solution to an optimization problem posed in terms of time-dependent logarithmic moment generating functions. Experimental results for Gaussian and Markov modulated fluid source models show that this asymptotic provides a better estimate of the frequency of buffer overflow than ones based on large buffer asymptotics. ATM SWITCHES; BUFFER OVERFLOW ASYMPTOTICS; EFFECTIVE BANDWIDTHS; LARGE DEVIATIONS; MARKOV MODULATED FLUID AMS 1991 SUBJECT CLASSIFICATION: PRIMARY 60K30, SECONDARY 60F10, 60K25, 68M20, 90B10, 90B22 1. Switches handling many bursty sources In a high speed data com...

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...

We propose a time-scale decomposition approach to measurement-based admission control (MBAC). We identify a critical time-scale T h such that: 1) aggregate traffic fluctuation slower than T h can be tracked by the admission controller and compensated for by flow admissions and departures; 2) fluctuations faster than T h have to be absorbed by reserving spare bandwidth on the link. The critical time-scale is shown to scale as T h = n, where T h is the average flow duration and n is the size of the link in terms of number of flows it can carry. An MBAC design is presented which filters aggregate measurements into low and high frequency components separated at the cutoff frequency 1= T h , using the low frequency component to track slow time-scale traffic fluctuations and the high frequency component to estimate the spare bandwidth needed. Our analysis shows that the scheme achieves high utilization and is robust to traffic heterogeneity, multiple time-scale fluctuations and measurement errors. The scheme uses only measurements of aggregate bandwidth and does not need to keep track of per-flow information.

We study link capacity allocation for a finite buffer system to transmit multimedia traffic. The queueing process is simulated with real video traffic. Two key concepts are explored in this study. First, the link capacity requirement at each node is essentially captured by its low frequency input traffic (filtered at a properly selected cut-off frequency). Second, the low frequency traffic stays intact as it travels through a finite-buffer system without significant loss. Hence, one may overlook the queueing process at each node for network-wide traffic flow in the low frequency band. We propose a simple, effective method for link capacity allocation and network control using on-line observation of traffic flow in the low frequency band. The study explores a new direction for measurement-based traffic control in high speed networks. The research reported here was supported by the National Science Foundation under grant NCR9015757 and by the Texas Advanced Research Program under grant...