TCP flow control mechanism for ATM networks

ABR rate-based flow control can effectively reduce the cell loss and buffer requirement in ATM switches thus improving the overall network performance. However, it is observed that the actual performance perceived by some ABR applications under rate-based flow control is worse than expected. The TCP is a good example of those kinds of applications. Since it is reasonable to think that rate-based flow control simply pushes the congestion from the switches to the source broadband terminal equipment (B-TE), we studied the behavior of the B-TE and propose a method that extends the rate-based flow control to the TCP layer. The proposed algorithm is simulated using the ATM Network Simulator from NIST with respect to the throughput and retransmission rate of the TCP. Simulations were performed on two cases and compared to each other. The first case (rate based TCP/ATM) uses rate based congestion control in the ATM switch. The second case (our suggested method) uses a window adjusting method in the B-TE and rate based congestion control on the ATM network. The results show that the overall TCP performance is improved when the second method is used.