Raif O. Onvural

Analysis of Queueing Networks with Blocking

Preface. Part I: Queueing Network Models with Blocking and Applications. 1. Introduction. 2. Queueing Networks with Blocking. 3. Application Examples of Queueing Networks with Blocking. Part II: Analysis of Queueing Networks with Blocking. 4. Exact Analysis of Markovian Networks. 5. Exact Analysis of Special Networks. 6. Approximate and Bound Analysis. Part III: Properties of Networks with Blocking. 7. Equivalence, Insensitivity and Monotonicity Properties. 8. Buffer Allocation in Queueing Networks with Finite Capacities. References. Table of Symbols. Index.

Routing in ATM networks

Asynchronous Transfer Mode (ATM) has been adopted by CCITT as the transport mode for B-ISDN. There are various performance issues that need to be resolved before B-ISDN networks can become a reality. In this paper, some of the performance issues in routing in ATM networks are addressed and the applicability of the routing concepts developed for today’s low bandwidth public and commercial communicatior s networks to B-ISDN networks is discussed.

Queueing Networks with Finite Capacities

In this paper, we give a tutorial of queueing networks with blocking. Except for a few special cases, these networks could not be shown to have product form solutions. Although the steady state queue length distributions of these networks can, in theory, be calculated by solving the global balance equations together with the normalization equation numerically, this procedure can, in practice, be restrictive due to the time complexity of the procedure and the large storage required to store the rate matrices, particularly for large networks. Since exact values of their steady state queue length distributions are, in general, not attainable, good approximation algorithms are required to analyze queueing networks with finite queues.

Buffer Allocation in Queueing Networks with Finite Capacities

In this chapter we study the buffer allocation problem in queueing networks with finite capacities. We present some solution techniques proposed in the literature for queueing networks with arbitrary topology.

Approximate and Bound Analysis

In this chapter we deal with approximate and bound methods to analyze queueing networks with blocking and to evaluate various performance indices. Section 6.1 introduces the basic ideas of the approximate method proposed in the literature. Sections 6.2 and 6.3 present some approximate solution techniques for closed and open networks with blocking, respectively. Section 6.4 deals with bound approximation methods.

Exact Analysis of Markovian Networks

In this chapter we deal with analytical solutions of a class of networks that can be represented by a continuous-time Markov process.

Equivalence, Insensitivity and Monotonicity Properties

Equivalence, insensitivity and monotonicity are important properties of queueing network models that can be used in system performance comparison and evaluation. Insensitivity and equivalence properties provide the basis for comparing the performance of system models with different parameters and with different blocking mechanisms. These results can be applied, for example, to study the impact of the blocking type on system performance, by considering a given set of performance indices and network parameters. In particular, equivalences allow us to define more efficient algorithms to evaluate queueing networks with blocking and to extend the class of models that can be analyzed through analytical methods. Insensitivity properties lead to the identification of the factor that affect system performance and in certain cases it allow a generalization of solution methods. Some important consequence of these properties is that solution methods and algorithms already defined for a certain class of networks could be extended to other classes of networks with different blocking types and/or network parameters. For example, equivalence between networks with and without blocking immediately leads to the extension of efficient computational solution algorithms defined for BCMP networks such as MVA and Convolution algorithm to queueing networks with finite capacity queues. Monotonicity provides insights in the system behavior represented by the queueing network models.

Application Examples of Queueing Networks with Blocking

As discussed in chapter 1, customers in real systems usually require different services provided by different servers. During this process, customers may wait in different queues in front of servers prior to start receiving services. Such complex service systems are often modeled using a network of queueing systems, referred to as a queueing network. The topology of the network represents the flow of customers from one service station to another to meet their service requirements. Hence, a queueing network is a connected directed graph whose nodes represent the service centers. The waiting area in front of a server is represented as a queue. That is, each service station has a queue associated with it. A connection between two servers indicates the one-step moves that customers may make from one service center to another service center. The route that a customer takes through the network may be deterministic or random. Customers may be of different types and may follow different routes through the network.

Computer communications TC

To fully realise the promise of emerging high speed networks we need: high bandwidth applications; networking standards; and networking services based on those standards. Two service models are being pursued to support high speed multimedia applications: IETF (Internet Engineering Task Force) and ATM (asynchronous transfer mode). The authors compare these models. They then discusses the future activities of the Computer Communications Technical Committee in this regard.

ATM FORUM AND ITS ACTIVITIES

ATM forum is a consortium of companies world wide. Its main mission is to speed up the development and deployment of ATM products through interoperability specifications. This paper reviews the ATM forum organization and various ATM specifications produced by the membership.