Fast backward congestion notification mechanism for TCP congestion control

The novel mechanism proposed uses a simple implementation to inform the traffic source at a very early stage that the network is becoming overloaded or congested and ask the source to slow down its transmission rate. Since TCP uses acknowledgments (ACKs) to adjust the number of packets sent over the network, the basic idea of our scheme is to control (or delay) TCP ACKs in the access node where its forward connection through the network is congested. To shorten the control loop, the congested network node generates ICMP (Internet control message protocol) source quench to initiate ACK control at the access node at the onset of congestion. By theoretical analysis and simulations, the mechanism is proven to be very effective in improving TCP throughput and fairness performance and reducing buffer occupancy. In particular, formulae for buffer occupancy and average throughput are derived relative to the distance between the congested node and the source terminal. It is important to note that TCP behavior does not have to be amended in any way.