What is the Burst Threshold value?

• A. Max possible burst
• B. Minimum rate
• C. Triggering point for calculations (1/2 max rate)
• D. Idle threshold

Answer: (C)

Burst threshold is the moment the burst mechanism starts counting and allows higher speeds. In a queue with burst settings, you have a normal limit, a burst limit, a burst time, and this threshold. The threshold is set at roughly half of the maximum burst rate, and when the current rate crosses that level, burst calculations begin so you can use up to the burst limit for the configured burst time. After the burst, the flow should drop back below the threshold to exit burst mode and return to normal.

For example, if the normal limit is 1000 kbit/s and the burst limit is 2000 kbit/s, the burst threshold would be about 500 kbit/s. Crossing that 500 kbit/s point enables the burst, letting you go up to 2000 kbit/s for the burst duration. This makes sense because it ties the decision to enable bursts to a defined midpoint of the allowed burst range, rather than to the absolute maximum or a separate idle/minimum rate.