Valens QoS Presentation - Priority

RouterOS Beginner Basics
1

In the above slide I see that priority is only applied if limit-at is reached/specified. Is this really true? I find MOST examples in the forums and wiki where limit-at is not specified, yet they are prioritizing packets.

How true is the slide above? Can someone reword it to be more specific? Does it mean limit-at AND max-limit have to be specified, or just max-limit? Does it mean inner queues completely ignore any priority specified on them? I see conflicting examples everywhere and so I’m not really sure what to believe anymore.

2

I see this in the HTB wiki manual:

Make a note that priority only works:

for leaf queues - priority in inner queue have no meaning.
if max-limit is specified (not 0)

So does this mean if a inner queue has a max-limit, but its leaf queues do not, then priority will be ignored?

3

great concern. I join the question!!!. Currently I have my quality of service with certain limitations not specified.

regards

4

Valens is right:

In another words, at first limit-at (CIR) of the all queues will be satisfied, only then child queues will try to borrow the necessary data rate from their parents in order to reach their max-limit (MIR).

Note: CIR will be assigned to the corresponding queue no matter what. (even if max-limit of the parent is exceeded)



We already know that limit-at (CIR) to all queues will be given out no matter what.

Priority is responsible for distribution of remaining parent queues traffic to child queues so that they are able to reach max-limit

Queue with higher priority will reach its max-limit before the queue with lower priority. 8 is the lowest priority, 1 is the highest.



**Make a note that priority only works:
\

  • for leaf queues - priority in inner queue have no meaning.
  • if max-limit is specified (not 0)**

This comes from the manual:
http://wiki.mikrotik.com/wiki/HTB

5

Also a suggestion to look at Example3 and Example4

6

I think I understand. So priority on inner queues is completely useless.

http://wiki.mikrotik.com/wiki/DSCP_based_QoS_with_HTB

In the above setup it shows lots of inner queues with leafs underneath each. Does this mean that those dont do anything?

Thx,
Sam

7

Yes it’s useless. By the way, you are referring to an article that’s not created by MikroTik, but by one of the users - Allen Eising (he is here on the forum)

8

setting priority for inner queue in this case is good for sorting, for good clarity …

9

understood. the sorting idea is good idea… nice to clarify that its not doing anything other than making it look pretty.

Sam