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 improves overall network performance. However, it is observed that the actual performance perceived by some ABR applications under rate-based flow control is worse than that it was expected. 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 B-TE, we studied the behavior of B-TE and propose a way that extends the rate-based flow control to the TCP layer. The proposed algorithm is simulated using ATM Network Simulator from NIST with respect to the throughput and retransmission rate of 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 ATM switch. The second case (our suggested method) uses window adjusting method in B-TE and rate based congestion control on ATM network. Results show that overall TCP performance is improved when suggested second method is used.