Dynamic bandwidth control in ATM networks

Abstract

The Asynchronous Transfer Mode (ATM) principle has been recommended by the ITU as the transport vehicle for future Broadband ISDN Networks. One of the most important objectives of ATM-based networks is to support multimedia traffic services. The multimedia traffic is a diverse mixture of several types of traffic (e.g., video, voice, image, data) that have different correlations, burstiness characteristics and quality of services (QoS) requirements form the network. Efficient bandwidth allocation and access control algorithms are required to ensure (and maintain) specific QoS requirements for each type of traffic. In this article, we propose and analyze a dynamic bandwidth allocation and control scheme based upon the virtual path (VP) principle. The scheme exploits the statistical multiplexing gain principle in order to increase the bandwidth utilization per VP. It allocates a certain amount of bandwidth to each VP that is necessary to meet the QoS requirements of the traffic carried by that VP. Each VP carries only homogeneous traffic (i.e., traffic with similar characteristics and QoS requirements are supported by a single VP). To dynamically control the allocated path-bandwidth a Bandwidth Control Period (BCP) rule is proposed to control the scheduling of different types of traffic that are supported by separate VPs. It is shown that with proper choice of the BCP, a path-bandwidth can be allocated to guarantee QoS required by the traffic. The scheme is dynamic in the sense that the bandwidth allocated, per VP, depends upon the number of accepted calls and variations in the traffic characteristics. Further, it is shown that access flow control is essential in order to minimize the cell loss rate and enhance the statistical multiplexing gain per VP.