In ATM networks, the available bit rate (ABR) service enables data sources to efficiently utilize network resources without adversely affecting the performance of non-ABR, guaranteed traffic such as video. Most research to date on ABR performance has not used realistic assumptions. Unrealistic assumptions such as persistent data sources, an absence of non-ABR traffic, and inaccurate TCP models may lead to misleading results. We address the above shortcomings of previous research. In a comparison of two major ABR schemes, the rate based Explicit Rate Indication for Congestion Avoidance (ERICA) and the credit based Quantum Flow Control (QFC), we find that the performance may be significantly better with QFC than previously thought when bursty traffic sources and bursty interfering traffic is considered.

The available bit rate (ABR) service dynamically utilizes free bandwidth in ATM networks for data traffic. ABR enables data sources to efficiently utilize network resources without adversely affecting the performance of guaranteed traffic such as for video. However, the majority of research to date on the performance of ABR schemes has ignored the effects of guaranteed traffic. The vast majority of research has also only utilized persistent sources although real data traffic, such as Internet traffic, is bursty. This paper presents a simulation study of bursty Internet TCP traffic over ATM with bursty interfering traffic streams. Two major ABR schemes, rate based ABR with explicit rate (ER) control and the credit based quantum flow control (QFC), are compared. The results indicate that performance with QFC is significantly better than with ER control.

The backward compatibility dilemma introduced by the deployment of a high-speed, wide-area asynchronous transfer mode (ATM) network is examined. The problem is that emerging ATM network must be capable of transporting traffic sources such as digital voice and video, but many of the design choices that optimize ATM for these sources make the transport of traditional connectionless data traffic difficult. The overlay of a virtual datagram network of connectionless servers onto a public ATM network to provide connectionless service is proposed to solve the problem. This method provides low transfer delay and efficiently utilizes network resources. Architectural issues are described, and an implementation of a connectionless server is presented.>