Why does RED/WRED dropping mechanism use the Average Queue Size and not just the actual queue size? How is it calculated using the Exponential Weight Factor?

Why does RED/WRED dropping mechanism use the Average Queue Size and not just the actual queue size? How is it calculated using the Exponential Weight Factor?

The concept of average queue size is used because fluctuations in the actual queue size should be allowed to accommodate bursty traffic and transient congestion.The average queue size is based on the previous average and the current size of the queue. The formula is:Average queue size = (old_average_queue_size * (1 - 1 / (2^expoential_weight_factor)) + (current_queue_size * 1 / (2^exponential_weight_factor)))For high values of exponential_weight_factor, the previous average becomes more important. A large exponential_weight_factor smooths out the peaks and lows in queue length. The average queue size is unlikely to change very quickly, avoiding drastic swings in size. The RED/WRED will be slow to start dropping packets, but it may continue dropping packets for a time after the actual queue size has fallen below the minimum threshold. The slow-moving average will accommodate temporary bursts in traffic.If the value of exponential_weight_factor gets too high, RED/WRED will not react to congestion. Packets will be transmitted or dropped as if RED/WRED were not in effect.For low values of exponential_weight_factor, the average queue size closely tracks the current queue size. The resulting average may fluctuate with changes in the traffic levels. In this case, The RED/WRED process responds quickly to long queues. Once the queue falls below the minimum threshold, the process will stop dropping packets.If the values of exponential_weight_factor gets too low, RED/WRED will overreact to temporary traffic bursts and drop traffic unnecessarily.

Protocols->QoS