Performance evaluation of TCP traffic over VBR in wide area ATM network

For ATM networks, variable bit rate (VBR) is one of the effective solutions to accommodate TCP/IP based LAN traffic. In order to guarantee high quality for the TCP traffic, it is important to select VBR parameter values appropriate for the TCP traffic and to clarify the interaction between the TCP flow control mechanism and the UPC (usage parameter control) function of ATM switch. We have, therefore, performed the experimental studies on TCP traffic over VBR based ATM networks. Through these experiments, we present the method for estimation of VBR parameters for the TCP traffic. Moreover, we investigate the TCP throughput degradation due to the discard of non-conforming cells by the UPC function where the insufficient UPC parameters are applied.