Improving the fairness of TCP over ATM WAN with the age priority packet discarding scheme

The performance degradation of TCP over a congested wide area ATM network is not trivial to solve with UBR services. The performance degradation can be alleviated if switch buffer management techniques such as early packet discarding (EPD) and partial packet discarding (PPD) schemes are employed. We show via simulation that fairness among connections remains a problem. To improve fairness of TCP over ATM WANs, we propose a new technique called the age priority packet discarding (APPD) scheme to be used along with EPD and PPD. The simulation shows that with APPD combined with EPD and PPD, fairness can be well maintained against order of connections, as well as different propagation delays. In addition, packet loss probability can be reduced with APPD in most scenarios.