Like [[random early detection]] (RED), itBlue operates by randomly dropping or marking packet with [[explicit congestion notification]] mark before the transmit buffer of the [[network interface controller]] overflows. Unlike RED, however, it requires little or no tuning to be performed by the network administrator. A Blue queue maintains a drop/mark probability ''p'', and drops/marks packets with probability ''p'' as they enter the queue. Whenever the queue overflows, ''p'' is increased by a small constant ''p<sub>i</sub>'', and whenever the queue is empty, ''p'' is decreased by a constant ''p<sub>d</sub> < p<sub>i</sub>''.
If the mix of traffic on the interface does not change, ''p'' will slowly converge to a value that keeps the queue within its bounds with full link utilization.
