A new rate coordination protocol for TCP and ABR congestion control

The implementation of an agent-based algorithm to coordinate the congestion control algorithms of the transmission control protocol (TCP) and the ATM (asynchronous transfer mode) ABR (available bit rate) cell-oriented switching architecture is overviewed. A new parameter (CWNDACR) is derived to ensure that even when the ATM switch queues are indicating no congestion, it is the switch (and not the source) which should control the increment in the TCP source rates. The simulation results show that coordination at the edge of the network makes better use of the available bandwidth and improves the TCP's performance over ATM ABR for a range of performance metrics such as the cell loss ratio, the packet retransmission ratio and the throughput.