# Manual:Queues - Burst

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## Theory

Burst is a feature that allows to satisfy queue requirement for additional bandwidth even if required rate is bigger that MIR (max-limit) for a short period of time.

Burst can occur only if average-rate of the queue for the last burst-time seconds is smaller that burst-threshold. Burst must stop if average-rate of the queue for the last burst-time seconds is bigger or equal to burst-threshold

Burst mechanism is simple - if burst is allowed max-limit value is replaced by burst-limit value. When burst is disallowed max-limit value remains unchanged.

1. burst-limit (NUMBER) : maximal upload/download data rate which can be reached while the burst is allowed
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) : basically this is value of burst on/off switch.
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

## Example

Values:

limit-at=1M

max-limit=2M

burst-threshold=1500k

burst-limit=4M

### Burst-time=16s

Average rate is calculated every 1/16 of burst time, so in this case 1s

Zero second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+0+0+0+0)/16=0Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
1,0 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+0+0+0+4)/16=250Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
2,0 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+0+0+4+4)/16=500Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
3,0 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+0+4+4+4)/16=750Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
4,0 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+4+4+4+4)/16=1000Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
5,0 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+4+4+4+4+4)/16=1250Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
6,0 second - average-rate=(0+0+0+0+0+0+0+0+0+0+4+4+4+4+4+4)/16=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
7,0 second - average-rate=(0+0+0+0+0+0+0+0+0+4+4+4+4+4+4+2)/16=1625Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
8,0 second - average-rate=(0+0+0+0+0+0+0+0+4+4+4+4+4+4+2+2)/16=1750Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
9,0 second - average-rate=(0+0+0+0+0+0+0+4+4+4+4+4+4+2+2+2)/16=1750Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
10,0 second - average-rate=(0+0+0+0+0+0+4+4+4+4+4+4+2+2+2+2)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps
11,0 second - average-rate=(0+0+0+0+0+4+4+4+4+4+4+2+2+2+2+0)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps
12,0 second - average-rate=(0+0+0+0+4+4+4+4+4+4+2+2+2+2+0+0)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps
13,0 second - average-rate=(0+0+0+4+4+4+4+4+4+2+2+2+2+0+0+0)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps
14,0 second - average-rate=(0+0+4+4+4+4+4+4+2+2+2+2+0+0+0+0)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps
15,0 second - average-rate=(0+4+4+4+4+4+4+2+2+2+2+0+0+0+0+0)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps
16,0 second - average-rate=(4+4+4+4+4+4+2+2+2+2+0+0+0+0+0+0)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps
17,0 second - average-rate=(4+4+4+4+4+2+2+2+2+0+0+0+0+0+0+0)/16=1625Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
18,0 second - average-rate=(4+4+4+4+2+2+2+2+0+0+0+0+0+0+0+2)/16=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
19,0 second - average-rate=(4+4+4+2+2+2+2+0+0+0+0+0+0+0+2+2)/16=1375Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
20,0 second - average-rate=(4+4+2+2+2+2+0+0+0+0+0+0+0+2+2+4)/16=1375Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
21,0 second - average-rate=(4+2+2+2+2+0+0+0+0+0+0+0+2+2+4+4)/16=1375Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
22,0 second - average-rate=(2+2+2+2+0+0+0+0+0+0+0+2+2+4+4+4)/16=1375Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps
23,0 second - average-rate=(2+2+2+0+0+0+0+0+0+0+2+2+4+4+4+4)/16=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
24,0 second - average-rate=(2+2+0+0+0+0+0+0+0+2+2+4+4+4+4+2)/16=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
25,0 second - average-rate=(2+0+0+0+0+0+0+0+2+2+4+4+4+4+2+2)/16=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
26,0 second - average-rate=(0+0+0+0+0+0+0+2+2+4+4+4+4+2+2+2)/16=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
27,0 second - average-rate=(0+0+0+0+0+0+2+2+4+4+4+4+2+2+2+2)/16=1625Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
28,0 second - average-rate=(0+0+0+0+0+2+2+4+4+4+4+2+2+2+2+2)/16=1750Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps
29,0 second - average-rate=(0+0+0+0+2+2+4+4+4+4+2+2+2+2+2+2)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps
30,0 second - average-rate=(0+0+0+2+2+4+4+4+4+2+2+2+2+2+2+0)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps
31,0 second - average-rate=(0+0+2+2+4+4+4+4+2+2+2+2+2+2+0+0)/16=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps

### Burst-time=8s

Average rate is calculated every 1/16 of burst time, so in this case 0,5s

Zero second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+0+0+0+0)/8=0Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
0,5 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+0+0+0+2)/8=250Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
1,0 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+0+0+2+2)/8=500Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
1,5 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+0+2+2+2)/8=750Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
2,0 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+0+2+2+2+2)/8=1000Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
2,5 second - average-rate=(0+0+0+0+0+0+0+0+0+0+0+2+2+2+2+2)/8=1250Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
3,0 second - average-rate=(0+0+0+0+0+0+0+0+0+0+2+2+2+2+2+2)/8=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
3,5 second - average-rate=(0+0+0+0+0+0+0+0+0+2+2+2+2+2+2+1)/8=1625Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
4,0 second - average-rate=(0+0+0+0+0+0+0+0+2+2+2+2+2+2+1+1)/8=1750Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
4,5 second - average-rate=(0+0+0+0+0+0+0+2+2+2+2+2+2+1+1+1)/8=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
5,0 second - average-rate=(0+0+0+0+0+0+2+2+2+2+2+2+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
5,5 second - average-rate=(0+0+0+0+0+2+2+2+2+2+2+1+1+1+1+1)/8=2125Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
6,0 second - average-rate=(0+0+0+0+2+2+2+2+2+2+1+1+1+1+1+1)/8=2250Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
6,5 second - average-rate=(0+0+0+2+2+2+2+2+2+1+1+1+1+1+1+1)/8=2375Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
7,0 second - average-rate=(0+0+2+2+2+2+2+2+1+1+1+1+1+1+1+1)/8=2500Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
7,5 second - average-rate=(0+2+2+2+2+2+2+1+1+1+1+1+1+1+1+1)/8=2625Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
8,0 second - average-rate=(2+2+2+2+2+2+1+1+1+1+1+1+1+1+1+1)/8=2750Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
8,5 second - average-rate=(2+2+2+2+2+1+1+1+1+1+1+1+1+1+1+1)/8=2625Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
9,0 second - average-rate=(2+2+2+2+1+1+1+1+1+1+1+1+1+1+1+1)/8=2500Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
9,5 second - average-rate=(2+2+2+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2375Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
10,0 second - average-rate=(2+2+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2250Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
10,5 second - average-rate=(2+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2125Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
11,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
11,5 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
12,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
12,5 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
13,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)
13,5 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+0)/8=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)
14,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+0+0)/8=1750Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)
14,5 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+0+0+0)/8=1625Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)
15,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+0+0+0+0)/8=1500Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)
15,5 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+0+0+0+0+0)/8=1375Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)
16,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+0+0+0+0+0+0)/8=1250Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)
16,5 second - average-rate=(1+1+1+1+1+1+1+1+1+0+0+0+0+0+0+0)/8=1125Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)
17,0 second - average-rate=(1+1+1+1+1+1+1+1+0+0+0+0+0+0+0+0)/8=1000Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
17,5 second - average-rate=(1+1+1+1+1+1+1+0+0+0+0+0+0+0+0+1)/8=1000Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
18,0 second - average-rate=(1+1+1+1+1+1+0+0+0+0+0+0+0+0+1+2)/8=1125Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
18,5 second - average-rate=(1+1+1+1+1+0+0+0+0+0+0+0+0+1+2+2)/8=1250Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
19,0 second - average-rate=(1+1+1+1+0+0+0+0+0+0+0+0+1+2+2+2)/8=1375Kbps, average-rate < burst-threshold -> Burst is allowed -> Actual-rate=4Mbps (2Mb per 0,5sek)
19,5 second - average-rate=(1+1+1+0+0+0+0+0+0+0+0+1+2+2+2+2)/8=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
20,0 second - average-rate=(1+1+0+0+0+0+0+0+0+0+1+2+2+2+2+1)/8=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
20,5 second - average-rate=(1+0+0+0+0+0+0+0+0+1+2+2+2+2+1+1)/8=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
21,0 second - average-rate=(0+0+0+0+0+0+0+0+1+2+2+2+2+1+1+1)/8=1500Kbps, average-rate = burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
21,5 second - average-rate=(0+0+0+0+0+0+0+1+2+2+2+2+1+1+1+1)/8=1625Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
22,0 second - average-rate=(0+0+0+0+0+0+1+2+2+2+2+1+1+1+1+1)/8=1750Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
22,5 second - average-rate=(0+0+0+0+0+1+2+2+2+2+1+1+1+1+1+1)/8=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
23,0 second - average-rate=(0+0+0+0+1+2+2+2+2+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
23,5 second - average-rate=(0+0+0+1+2+2+2+2+1+1+1+1+1+1+1+1)/8=2125Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
24,0 second - average-rate=(0+0+1+2+2+2+2+1+1+1+1+1+1+1+1+1)/8=2250Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
24,5 second - average-rate=(0+1+2+2+2+2+1+1+1+1+1+1+1+1+1+1)/8=2375Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
25,0 second - average-rate=(1+2+2+2+2+1+1+1+1+1+1+1+1+1+1+1)/8=2500Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
25,5 second - average-rate=(2+2+2+2+1+1+1+1+1+1+1+1+1+1+1+1)/8=2500Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
26,0 second - average-rate=(2+2+2+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2375Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
26,5 second - average-rate=(2+2+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2250Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
27,0 second - average-rate=(2+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2125Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
27,5 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
28,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
28,5 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
29,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
29,5 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
30,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=2Mbps (1Mb per 0,5sek)
30,5 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1)/8=2000Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)
31,0 second - average-rate=(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+0)/8=1875Kbps, average-rate > burst-threshold -> Burst not allowed -> Actual-rate=0Mbps (0Mb per 0,5sek)