Rate-based flow control and it's application in IP/ATM internetworks

In this presentation, we review the ABR rate based flow control and discuss the necessity for considering end-to-end traffic management in IP/ATM Internetworks. In particular we consider the impact of the interactions between the TCP and the ABR flow control loops in providing end-to-end quality of service to the user. We also discuss the trade-off in the memory requirements between the switch and edge device based on the type of flow control employed within the ATM subnetwork. The ABR rate control pushes the congestion out of the ATM subnetwork and into the edge devices. We show that this can have a detrimental effect on the end-to-end performance where the buffers at the edge device are limited. In such cases we show that UBR with Early Packet Discard can achieve better performance than ABR. Further work needs to be done on the possibilities of coupling the information in the two flow control loops to improve the performance as seen by the end-user.