Can someone explain the following to me:

"Bursts are used to allow higher data rates for a short period of time. Every 1/16 part of the burst-time, the router calculates the average data rate of each class over the last burst-time seconds. If this average data rate is less than burst-threshold, burst is enabled and the actual data rate reaches burst-limit bps, otherwise the actual data rate falls to max-limit or limit-at." - from http://www.mikrotik.com/testdocs/ros/2.9/root/queue.php

Firstly, what is meant by last burst time? Isn't their only one burst time?

Secondly, does this mean that if the burst time is 1700 then the first time the router checks to see if the traffic is over the threshold is at 106.25 seconds? If so, then please explain this to me:

"the average data rate is (0+0+0+0+0+0+0+512)/8=64kbps, which is under burst-threshold. After the second second, average data rate is (0+0+0+0+0+0+512+512)/8=128kbps." - from http://www.mikrotik.com/testdocs/ros/2.9/root/queue.php

Wouldn't the proper equation be: (iteration*(burst time/16)*burst limit)/burst time = average data rate ? But in your equation you left out the 1/16. SO, is it polled every 1/16 of the burst time or every second?

I want to be able to--and I am sure that a lot of other people want this as well--burst a user's actual rate, not the average for a set period of time. If your equation holds true, then I should be able to easily do this by reversing it and plugging in my desired value:

burst time = (burst limit * poll time)/burst threshold

So if I want someone to burst for 5 minutes (300 sec) at 5120k and my threshold is 512k then I should be able to get the burst time that I need for this by:

(5120k * 300s) / 512k = 3000s

The kilobits even cancel out properly. So I should be able to use these settings and get 5 minutes at 5120k and then 512k from there on out. If the router only polls every 1/16 of the burst time then the burst should be disabled at 375 sec (6.25 minutes).

The problem is that this doesn't work! I tested it.

Tell me, is there a bug? What equation should I use to get the results I need?

Also, what does the queue-type setting do in WinBox? Does this setting affect what I am talking about?

I never have found a very good explanation of this... here's my best shot.

Firstly, what is meant by last burst time? Isn't their only one burst time?

My understanding is that the router looks at the average usage measured over the time interval as defined by the burst time. So, if the burst time is 30 seconds, Mik looks at the average traffic over the most recently measured "burst time", which is 30 seconds in my example.

I'm headed out the door, so I really could not digest your theory : - )

But, as I understand it, the Router keeps looking at the average usage over repeated successive time intervals as defined by the "burst time". This is the "Average" for the following resulting action:

The user will be given the "Burst Limit" so long as the "Average" is below "Burst Threashold".

The user will be given the "Max Limit" when ever their "Average" is above the "Burst Threashold".

As you imagine this playing out you can see that there are a wide range of possilities depending upon the ratios between the "Max Limit", "Burst Limit" and the "Burst Threashold".

But my understanding of best practice, learned at a mikrotik training session was that the Burst Threashold should only be slightly above the "Max Limit".


One thing that I have never fully understood is the mechanism by which a user is re-allowed to "Burst" after having been droped down to the "Max Limit".

Is it merely when ever their "Average" is above the "Burst Threashold"?

If that is true then in the case of a long constant download case (simple queue) a user's "average" would constantly and repeatedly fluctuate above and below the "Burst Threashold" as the user was given "Max Limit" or "Burst Limit" speeds... it would seem like you would want a user to fall below the "Max Limit" for some period of time befor a burst was allowed again.......

Well I am not quite sure what you mean by the time interval as defined by the burst time. Because according to the documentation it will measure it every 1/16 of the burst time. Do you know if this is the case or not?

Yeah I can see the reasoning behind using the average if the threshold is above the limit, but there are many users who want the threshold to be the same as or below the max limit and in this case, using the average rate is completely idiotic.

The 'theory' that I have is that the queuing in the mikrotiks is next to useless. If I am up in the night on this one I wish that one of the developers would look at my post and correct me where I am wrong or fix the bug in the 'simple' queueing.