End-to-end adaptive rate based congestion control scheme for ABR service in wide area ATM networks

The ATM Forum is currently in the process of adopting an end-to-end adaptive rate based control scheme to support a class of best effort service known as available bit rate service (ABR). This is a reactive control method where the source rate adapts to the state of the network based on the feedback it receives from the network. The performance of such reactive feedback control schemes are sensitive to the latency in the feedback loop. In wide area networks the virtual channels traversing large hops can have very poor performance because of large propagation delays. We show that the performance of virtual channels (VCs) traversing a large number of hops in WANs can be substantially improved by giving priority to network transit traffic over traffic entering the network. We investigate the performance of the control in the presence of high priority variable bit rate traffic. The study shows that the priority scheme exhibits a robust behavior and ensures a fair share of the bandwidth for all VCs, regardless of the number of hops they traverse even under extreme loading conditions.