TCP Rate Control Using Active ECN Mechanism with RTT-Based Marking Probability

The end-to-end TCP congestion control based on a window flow control mechanism can cause unfairness among multiple TCP connections with different RTT (round trip time), dut to its non-uniform increase of the rate. In order to achieve the fairness among TCP connections, we propose a rate control scheme using ECN (Explicit Congestion Notification) on TCP congestion control. At an ECN-implemented router, ACK packets of each connection are set an ECN bit with a different probability according to the RTT. Since TCP senders reduce their congestion window sizes whenever they receive an ACK with an ECN bit, the proposed scheme can realize the same transmission rate among TCP connections with different RTTs. Computer simulation results show that the proposed rate control can drastically improve the fairness.