High-speed fast-packet-switched network architectures are capable of supporting a wide range of connections with different bandwidth requirements and traffic characteristics. While this environment provides increased flexibility in supporting various services, its dynamic nature poses difficult traffic control problems when trying to achieve efficient use of network resources. One such a problem is the issue of bandwidth management and allocation. Because of the statistical multiplexing of all connections at the physical layer and the variations of connections bit rate, it is important to characterize, for a given Grade-Of-Service (GOS), both the effective bandwidth requirement of a single connection and the aggregate bandwidth usage of multiplexed connections. In this paper, we 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 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 in the paper 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 in the paper is verified by comparison to both exact computations and simulation results.