OPNET implementation and performance evaluation of the CoDel AQM algorithm

The queuing algorithm directly affects the latency of a packet by determining how long a packet remains in the queue before it is sent. In this paper, one of the recently appearing AQM algorithms called Controlled Delay (CoDel) is studied. The CoDel algorithm is designed to address the Bufferbloat problem, and it relies on dropping packets to notify the transmitter of congestion when the delay time of the packets exceeds the target delay. A custom model was built in the OPNET program to study the performance of the algorithm and investigate the effect of the time interval, which is the time that the CoDel controller waits before starting the process of dropping packets to address the congestion situation, on the delay time and dropping packets. The results show that the CoDel algorithm is sensitive to its parameter settings, and requires appropriate adjustments to get good control queue delay and a constant rate of delay compared to the tail drop method.