The authors propose a computationally simple approximate expression for the equivalent capacity or bandwidth requirement of both individual and multiplexed connections, based on their statistical characteristics and the desired grade-of-service (GOS). The purpose of such an expression is to provide a unified metric to represent the effective bandwidth used by connections and the corresponding effective load of network links. These link metrics can then be used for efficient bandwidth management, routing, and call control procedures aimed at optimizing network usage. While the methodology proposed can provide an exact approach to the computation of the equivalent capacity, the associated complexity makes it infeasible for real-time network traffic control applications. Hence, an approximation is required. The validity of the approximation developed is verified by comparison to both exact computations and simulation results. >

/pdf/equivalent-capacity-and-its-application-to-bandwidth-4fytcdoedy.pdf

Equivalent capacity and its application to bandwidth allocation in high-speed networks

The Asynchronous Transfer Mode (ATM) is the switching and multiplexing technique chosen by CCITT for the broadband access to the ISDN. The user-network interface offers one physical channel over which connections are multiplexed using short, fixed length packets (called cells). The ATM layer in the network performs relaying functions, with every cell carrying a label used for switching. This report is a tutorial. It aims at providing the reader with background information that is necessary to understand the debate about potential virtues and shortcomings of the ATM.

The Asynchronous Transfer Mode: a tutorial

Some of the congestion control methods commonly considered suitable for an ATM (asynchronous transfer mode) network are surveyed. Call-level control, which provides preventive control by regulating the admission of new calls into the network, is first discussed. The concept of equivalent bandwidth is defined, and the sharing of network information is discussed. Admission control schemes are described. Methods for cell-level control, which avoids short term congestion, are considered. Included are call admittance, bandwidth policing, and rate control, as well as priority schemes that provide multiple grades of service with ATM. >

Congestion control and prevention in ATM networks

The protocols and mechanisms necessary for network bandwidth management and congestion control are addressed. The discussion draws heavily on the lessons learned from the design and implementation of plaNET, a high-speed packet-switching system for integrated voice, video, and data communications. A general overview of the mechanisms involved is given. The individual components of the system are discussed. Most of the conclusions are general and can be applied to other high-speed networks, including asynchronous transfer mode (ATM) systems. >

Bandwidth management and congestion control in plaNET

Asynchronous transfer mode (ATM) technology is discussed in relation to the requirements of corporate networking. An introduction to ATM switch architecture is presented. The various approaches to ATM switch design that have appeared in previously published literature are reviewed. A discussion is presented of some current issues facing the development of the ATM networks. It is argued that much simpler solutions to many of these issues may be adopted in the context of the corporate network than is permissible for the public broadband network. >

ATM technology for corporate networks

The concept of equivalent bandwidth of bursty traffic sources is investigated. The equivalent bandwidth measure depends on the source characteristics, the grade of service, and the interaction with the other type of traffic multiplexed on the same data link. The behavior of the statistical multiplexer is analyzed with inputs consisting of homogeneous bursty sources. The values of the equivalent bandwidth are analyzed for fixed statistical characteristics of the bursty sources and a fixed grade of service, and as a function of a background stream load. By assuming that the peak rate of the sources is sufficiently lower than the link rate (e.g. 1/15) and that the average burst length is greater than the queue length, the equivalent bandwidth independence of the average burst length and of the queue length is shown by simulation. The superposition of two heterogeneous bursty classes is analyzed. >

http://ieeexplore.ieee.org/iel2/123/3395/00117194.pdf

On bandwidth allocation to bursty virtual connections in ATM networks

Asynchronous transfer mode (ATM) is being considered as the primary choice for switching and transmission in future broadband ISDN public networks. Synchronous transfer mode (STM) based upon SONET and SDH standards would be used to build up the digital multiplexing hierarchy, while ATM would be used end-to-end throughout the transmission links and switching nodes of wide area networks for the transport of all forms of voice, data, and image traffic. An examination is made of the rationale for considering ATM as the basis for B-ISDN, and issues that indicate that a network based exclusively upon ATM as currently defined may not be optimal nor even achievable are discussed. >

http://ieeexplore.ieee.org/iel2/541/4226/00162553.pdf

Open issues regarding the universal application of ATM for multiplexing and switching in the B-ISDN

The paper presents the ATM test-bed, i.e. an experimental plant designed and implemented in Italy to investigate the critical issues related to the introduction of asynchronous transfer mode (ATM) techniques in a broadband communication environment. The general layout of the test-bed is described with focus on both the rationale of its single/global features and the architectural aspects. Some perspectives for enriching the initial configuration of the test-bed and for exploiting the experimental plant are also introduced. Finally, some instances of demonstration to give insights of the test-bed capabilities are illustrated. >

M. Decina

Papers

On bandwidth allocation to bursty virtual connections in ATM networks

Open issues regarding the universal application of ATM for multiplexing and switching in the B-ISDN

A laboratory plant for experimenting broadband communications in an ATM environment