Buffer management and rate guarantees for TCP over satellite-ATM networks

Future broadband satellite networks will support a variety of service types . Many such systems are being design with ATM or ATM-like technology. A maj ority of Internet applications use TCP for data transfer. As a result, thes e systems must efficiently transport TCP traffic and provide service guaran tees to such traffic. Several mechanisms have been presented in recent lite rature to improve TCP performance. Most of these can be categorized as eith er TCP enhancements or network-based buffer management techniques. Providin g minimum rate guarantees to TCP traffic has also been suggested as a way t o improve its performance in the presence of higher priority traffic sharin g the link. However, the relative performance of the TCP enhancements versu s the buffer management schemes has not been analyzed for long latency netw orks. In this paper, we address three issues. First, we present a performan ce analysis of TCP over satellite-ATM links using a best effort service-the ATM unspecified bit rate (UBR) service. This analysis shows that the relat ive impacts of buffer management, TCP policies and rate guarantees on TCP p erformance, depend heavily on the latency of the network. Second, we show t hrough simulations that the buffer size required in the network for high TC P performance is proportional to the delay-bandwidth product of the network . Third, we propose a buffer management scheme called differential fair buf fer allocation (DFBA) and show how it is used to implement a service that p rovides minimum rate guarantees to TCP traffic. An example of such a servic e is the ATM guaranteed frame rate (GFR) service, which is being standardiz ed by the ATM Forum and the ITU. Copyright (C) 2001 John Wiley & Sons, Ltd.