Effect of gateway buffer management policies on TCP over ATM performance

In this paper, we examine the effect of the buffer management policies, used at the IP/ATM gateway, on the end-to-end performance seen by IP traffic when using the ATM ABR service class. The ABR service class uses feedback-based flow control at the ATM layer to dynamically partition bandwidth among active ABR virtual circuits. It is likely that the ABR service will be operated in a manner designed to achieve nearly loss free operation in the core of the ATM network, causing most of the buffering requirements to be pushed to the ingress points of the ATM network. In our traffic model, an ingress IP/ATM gateway is responsible for setting up ATM virtual circuits and mapping IP packets onto ATM virtual circuits. In this model of network transport, the IP/ATM gateways serve as ABR source and destination end-points. Since the buffering available at an IP/ATM gateway will typically be small relative to the worst case buffer buildups that can occur due to transient overloads in the ATM network. Therefore, the buffer management policy can significantly impact the end to end performance