queue priorities/limit-at questions

my provider is 5mbps/50mbps
i set a “lan” parent queue with max limits 2M/30M
first child queue “server” with max 2M/20M and limit-at 1M/20M
second child queue “other” with max 2M/20M and limit-at 1M/20M

shouldnt total maximum download speed be 30M as parent queue says!
why is 40M download speed? i know i have limit-at 20M and 20M to childs. but at parent i say i got only 30M.
Screenshot 2018-04-11 18.51.03.png

The sum of limit-at from child queues shouldn’t be more than max-limit of parent queue.
If the sum is more than max-limit, will pass the max-limit to guarantee the limit-at.
In your case, you must use limit-at on “other” as 1M/10M.

Understand the limit-at as guarantee of bandwidth, so the queue will try to satisfy the condition before apply the max-limit.

A example: https://wiki.mikrotik.com/wiki/Manual:HTB#Example_4_:_Leaf_queue_limit-at

ok i understand. thank you.
for others information if you set limit-at “unlimited” then the max-limit of parent applies.
Screenshot 2018-04-11 21.26.30.png