In telecommunications and computer engineering, the queuing delay is the time a job waits in a queue until it can be executed.
The speed at which the contents of a queue can be processed is a function of the transmission rate of the facility.
When the transmission protocol uses the dropped-packets symptom of filled buffers to regulate its transmit rate, as the Internet's TCP does, bandwidth is fairly shared at near theoretical capacity with minimal network congestion delays.
Absent this feedback mechanism the delays become both unpredictable and rise sharply, a symptom also seen as freeways approach capacity; metered onramps are the most effective solution there, just as TCP's self-regulation is the most effective solution when the traffic is packets instead of cars).
Failing to drop packets, choosing instead to buffer an ever-increasing number of them, produces bufferbloat.
Kendall's notation should be used to calculate the queuing delay when packets are dropped from the queue.