Experimental Evaluation of ATM Congestion Control Mechanisms
INFOCOM '97 Proceedings of the INFOCOM '97. Sixteenth Annual Joint Conference of the IEEE Computer and Communications Societies. Driving the Information Revolution
Issues in improving TCP performance over ATM
Computer Communications
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We study the performance of TCP/IP on a multi-hop ATM network by simulation in an effort to evaluate the effectiveness of various congestion-control schemes at the ATM layer. The congestion control schemes considered are the ATM-Early Packet Discard (ATM-EPD) and link-level flow control. The performance of these schemes are compared against that of an ATM layer with no congestion control, as well as TCP/IP over a datagram network. We compare the schemes in terms of the throughputs obtained by long and short connections, number of retransmissions, end-to-end delays, and fairness in bandwidth allocation between connections with unequal round-trip delays. Our results show that significant unfairness in the amount of bandwidth allocated to connections may result in a large ATM network if no congestion control policies are used at the ATM layer. The ATM-EPD scheme is able to remove some of the unfairness, providing performance close to that of a datagram network, but can still provide unacceptable performance if the buffer sizes in the switches are small. Link-level flow control provided the best performance among the schemes studied.