Fuzzy Logic Congestion Control in TCP/IP Tandem Networks

Network resource management and control is a complex problem that requires robust, possibly intelligent, control methodologies to obtain satisfactory performance. While many Active Queue Management (AQM) mechanisms have been introduced to assist the TCP congestion control, these require careful configuration of non-intuitive control parameters, and show weaknesses to detect and control congestion under dynamic traffic changes, and a slow response to regulate queues. Furthermore, there is also a need to evaluate thoroughly the performance of such mechanisms for tandem networks containing multiple congested routers. A new AQM scheme, Fuzzy Explicit Marking (FEM) has recently been proposed to provide congestion control in TCP/IP best-effort networks using a fuzzy logic control approach. We present the control approach followed by the FEM controller, and evaluate the performance of FEM and a number of representative AQM schemes (A-RED, PI and REM) in a tandem network. An extensive simulation study over a wide range of traffic conditions shows that the FEM controller outperforms the other schemes in terms of queue fluctuations and delays, packets losses, link utilization, and speed of response to regulate queues.