INTERNATIONAL JOURNAL OF DIGlTAL AND ANALOG COMMUNICATION SYSTEMS, VOL. 3, 199-209 (1990) AN APPROACH TO CONTROLLING CONGESTION IN ATM NETWORKS A. E. ECKBERG, JR., D. T. LUAN AND D. M. LUCANTONI AT&T Bell Laboratories, Crawfords Corner Road, Holmdel, New Jersey 07733-1988, U.S.A. SUMMARY Determining approaches to congestion and flow control, especially real-time components in an overall strategy, is recognized as one of the fundamental challenges facing broadband 'packet-based' information transport, as, for instance, in the case of BISDN/ATM. In this paper we summarize basic issues underlying this subject, and describe a particular approach to achieving a multilayer broadband congestion, flow and error-control architecture, based on a 'core' congestion control strategy that we term bandwidth management. The modular and layered nature of this control architecture is described, and shown to lend itself to a structured approach to characterizing the control architecture performance. KEY WORDS Traffic monitoring Violation tag Control layering Control separation Leaky bucket 1. INTRODUCTION Broadband ISDN (BISON) architectures, built on a technology base of information transport via asynchronous transfer mode (ATM),J,2 offer a means for the efficient integrated transport for a broad spectrum of services, from voice and low- speed data to high-speed data and video telephony. Although well-thought-out engineering and adminis- tration rules will probably result in excellent end- to-end performance in such networks most of the time, a fundamental challenge in the design of robust BISDN architectures is the structuring of a comprehensive strategy for congestion and flow controls, which will be essential during those (hopefully rare) instances of resource overloads due to unforeseen traffic focusing and peaking, as well as during network component failures. Unfortunately, the multi-megabit-per-second speeds that will be responsible for the high performance/capacity of BISON/ ATM networks will also severely limit the number of implementable and stable congestion control strategies. In this paper we address a number of basic issues in the area of congestion and flow control strategies suitable for BISDN/ATM, and suggest a specific BISDN/ATM congestion/flow/error-control archi- tecture. We begin, in Section 2, by summarizing goals, issues, and several guiding principles that underlie the selection of such a control architecture. Section 3 describes a bandwidth management-based congestion/flow/error control architecture that is motivated by some of the considerations laid out in Section 2. Then, Section 4 describes a modular approach to achieving a traffic/performance charac- terization of this control architecture. Finally, in 1047-9627/90/020199-11$05.50 © 1990 by John Wiley & Sons, Ltd. Section 5 we address some commonly asked ques- tions regarding the proposed congestion control strategy. 2. UNDERLYING ASSUMPTIONS, MAJOR ISSUES AND GUIDING PRINCIPLES There are two, fundamentally different, approaches to determining control architectures for complex systems such as BISDN/ATM networks: an inside- out approach in which each component in an overall architecture is looked at individually, without excessive attention given to component interwork- ing, and an outsidewin approach, in which a global, 'system' view is taken of the entire system. It is the inside-out approach which typically must be taken during experimentation in technology advancement and component prototyping, in particular to deter- mine component functionalities that are feasible to implement. However, at an appropriate point in technology development it becomes necesary to switch to an outside-in approach, so that the entire system can be characterized as a single entity, and so that system-wide strategies that may make global sense arc not unnecessarily prevented by individual component limitations. It is an outside-in approach which we attempt to take in this paper focusing on issues and character- istics of entire BISDN/ A TM information transport systems. Therefore, in this section we list some of the assumptions we are making concerning the characteristics of BISDN/ATM networks and the information movement and management environ- ments they will be supporting. These assumptions then lead to a number of high-level objectives and Received 5 January 1990 Revised 19 April 1990