Burst

Manual:Queues - Burst 1
Manual:Queues - Burst
Applies to RouterOS: 2.9, v3, v4
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 limited 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 will 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) : 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
Manual:Queues - Burst 2
Example
Values: limit-at=1M , max-limit=2M , burst-threshold=1500k , burst-limit=4M
Client will try to download two 4MB (32Mb) blocks of data, first download will start at zero seconds, second
download will start at 17th second. Traffic was unused for last minute.
Burst-time=16s
As we can see as soon as client requested bandwidth it was able to get 4Mpbs burst for 6 seconds. This is longest
possible burst with given values (longest-burst-time = burst-threshold * burst-time / burst-limit). As soon as burst
runs out rest of the data will be downloaded with 2Mbps. This way block of data was downloaded in 9 seconds -
without burst it would take 16 seconds. Burst have 7 seconds to recharge before next download will start.
Note that burst is still disallowed when download started and it kicks in only afterwards - in the middle of download.
So with this example we proved that burst may happen in the middle of download. Burst was ~4 seconds long and
second block of was downloaded 4 seconds faster then without burst.
Average rate is calculated every 1/16 of burst time, so in this case 1s
Time average-rate burst actual-rate
0 (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 4Mbps
1 (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 4Mbps
2 (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 4Mbps
3 (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 4Mbps
4 (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 4Mbps
5 (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 4Mbps
6 (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 2Mbps
7 (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 2Mbps
8 (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 2Mbps
9 (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 2Mbps
10 (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 0Mbps
Manual:Queues - Burst 3
11 (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 0Mbps
12 (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 0Mbps
13 (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 0Mbps
14 (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 0Mbps
15 (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 0Mbps
16 (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 0Mbps
17 (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 2Mbps
18 (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 2Mbps
19 (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 4Mbps
20 (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 4Mbps
21 (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 4Mbps
22 (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 4Mbps
23 (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 2Mbps
24 (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 2Mbps
25 (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 2Mbps
26 (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 2Mbps
27 (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 2Mbps
28 (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 2Mbps
29 (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 0Mbps
30 (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 0Mbps
31 (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 0Mbps
Burst-time=8s
Manual:Queues - Burst 4
If we decrease burst-time to 8 seconds - we are able to see that in this case bursts are only at the beginning of
downloads
Average rate is calculated every 1/16th of burst time, so in this case every 0.5 seconds.
Time average-rate burst actual-rate
0.0 (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 4Mbps (2Mb per 0,5sek)
0.5 (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 4Mbps (2Mb per 0,5sek)
1.0 (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 4Mbps (2Mb per 0,5sek)
1.5 (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 4Mbps (2Mb per 0,5sek)
2.0 (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 4Mbps (2Mb per 0,5sek)
2.5 (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 4Mbps (2Mb per 0,5sek)
3.0 (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 2Mbps (1Mb per 0,5sek)
3.5 (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 2Mbps (1Mb per 0,5sek)
4.0 (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 2Mbps (1Mb per 0,5sek)
4.5 (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 2Mbps (1Mb per 0,5sek)
5.0 (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 2Mbps (1Mb per 0,5sek)
5.5 (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 2Mbps (1Mb per 0,5sek)
6.0 (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 2Mbps (1Mb per 0,5sek)
6.5 (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 2Mbps (1Mb per 0,5sek)
7.0 (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 2Mbps (1Mb per 0,5sek)
7.5 (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 2Mbps (1Mb per 0,5sek)
8.0 (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 2Mbps (1Mb per 0,5sek)
8.5 (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 2Mbps (1Mb per 0,5sek)
9.0 (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 2Mbps (1Mb per 0,5sek)
9.5 (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 2Mbps (1Mb per 0,5sek)
10.0 (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 2Mbps (1Mb per 0,5sek)
10.5 (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 2Mbps (1Mb per 0,5sek)
11.0 (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 2Mbps (1Mb per 0,5sek)
11.5 (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 2Mbps (1Mb per 0,5sek)
12.0 (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 2Mbps (1Mb per 0,5sek)
12.5 (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 2Mbps (1Mb per 0,5sek)
13.0 (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 0Mbps (0Mb per 0,5sek)
13.5 (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 0Mbps (0Mb per 0,5sek)
14.0 (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 0Mbps (0Mb per 0,5sek)
14.5 (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 0Mbps (0Mb per 0,5sek)
15.0 (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 0Mbps (0Mb per 0,5sek)
15.5 (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 0Mbps (0Mb per 0,5sek)
16.0 (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 0Mbps (0Mb per 0,5sek)
16.5 (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 0Mbps (0Mb per 0,5sek)
17.0 (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 2Mbps (1Mb per 0,5sek)
Manual:Queues - Burst 5
17.5 (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 4Mbps (2Mb per 0,5sek)
18.0 (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 4Mbps (2Mb per 0,5sek)
18.5 (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 4Mbps (2Mb per 0,5sek)
19.0 (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 4Mbps (2Mb per 0,5sek)
19.5 (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 2Mbps (1Mb per 0,5sek)
20.0 (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 2Mbps (1Mb per 0,5sek)
20.5 (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 2Mbps (1Mb per 0,5sek)
21.0 (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 2Mbps (1Mb per 0,5sek)
21.5 (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 2Mbps (1Mb per 0,5sek)
22.0 (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 2Mbps (1Mb per 0,5sek)
22.5 (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 2Mbps (1Mb per 0,5sek)
23.0 (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 2Mbps (1Mb per 0,5sek)
23.5 (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 2Mbps (1Mb per 0,5sek)
24.0 (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 2Mbps (1Mb per 0,5sek)
24.5 (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 2Mbps (1Mb per 0,5sek)
25.0 (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 2Mbps (1Mb per 0,5sek)
25.5 (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 2Mbps (1Mb per 0,5sek)
26.0 (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 2Mbps (1Mb per 0,5sek)
26.5 (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 2Mbps (1Mb per 0,5sek)
27.0 (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 2Mbps (1Mb per 0,5sek)
27.5 (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 2Mbps (1Mb per 0,5sek)
28.0 (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 2Mbps (1Mb per 0,5sek)
28.5 (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 2Mbps (1Mb per 0,5sek)
29.0 (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 2Mbps (1Mb per 0,5sek)
29.5 (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 2Mbps (1Mb per 0,5sek)
30.0 (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 2Mbps (1Mb per 0,5sek)
30.5 (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 0Mbps (0Mb per 0,5sek)
31.0 (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 0Mbps (0Mb per 0,5sek)
Article Sources and Contributors 6
Article Sources and Contributors
Manual:Queues - Burst Source: http://wiki.mikrotik.com/index.php?oldid=16948 Contributors: Eep, Janisk, Marisb, Megis
Image Sources, Licenses and Contributors
Image:Version.png Source: http://wiki.mikrotik.com/index.php?title=File:Version.png License: unknown Contributors: Normis
Image:Burst time.16.part1.JPG Source: http://wiki.mikrotik.com/index.php?title=File:Burst_time.16.part1.JPG License: unknown Contributors: Megis
Image:Burst time.16.part2.JPG Source: http://wiki.mikrotik.com/index.php?title=File:Burst_time.16.part2.JPG License: unknown Contributors: Megis
Image:Burst time.8.part1.JPG Source: http://wiki.mikrotik.com/index.php?title=File:Burst_time.8.part1.JPG License: unknown Contributors: Megis
Image:Burst time.8.part2.JPG Source: http://wiki.mikrotik.com/index.php?title=File:Burst_time.8.part2.JPG License: unknown Contributors: Megis