# Manual:Queues - Burst

## Theory

To understand burst it is necessary to be aware of 5 concepts:

1. burst-limit (NUMBER) : maximal upload/download data rate which can be reached while the burst is active
2. burst-time (TIME) : period of time, in seconds, over which the average data rate is calculated. (This is NOT the time of actual burst)
3. burst-threshold (NUMBER) : when average data rate is below this value - burst is allowed, as soon as average data rate reach this value - burst is denied. (basically this is burst on/off switch). For optimal burst behavior this value should above limit-at value and below max-limit value
4. average-rate (read-only) : Every 1/16 part of the burst-time, the router calculates the average data rate of each class over the last burst-time seconds.
5. actual-rate (read-only) : actual traffic transfer rate of the queue

To simplify calculations for examples we will use limit-at=1M, max-limit=2M, burst-threshold=1500k, burst-limit=4M

## Example Burst-time=8s

Seconds Actual Rate Average Rate Allow Burst
0 0Mbps (0+0+0+0+0+0+0+0)/8=0Mbps Yes