Dummynet Queue Weighting

Ian FREISLICH if at hetzner.co.za
Fri Jul 9 01:19:51 PDT 2004


> > # SAMPLE CONFIG
> > ipfw queue 1 ip from A to B
> > ipfw queue 1 config weight 10 pipe 1
> > ipfw queue 2 ip from C to D
> > ipfw queue 2 config weight 5 pipe 1
> > ipfw queue 3 ip from E to F
> > ipfw queue 3 config weight 1 pipe 1
> > ipfw pipe 1 config bw 1000Kbit/s
> >
> > Question?
> >
> > When setting up queues as I have done above with different weights
> > they (the queues) will share the assigned pipe proportionate to
> > their weight.
> >
> > For example if you had traffic on all three queues, the A&B(1),
> > C&D(2), and E&F(3); they would get 10/16, 5/16, and 1/16 of the
> > pipe, respectively.
> >
> > But, what if A&B(1) had no traffic? It is my understanding that
> > queue 2 and 3 would still only get 5/16 and 1/16 of the pipe
> > regardless. In this example, 3/8 or 375Kb/s total. Or would 2 and
> > 3 share the whole pipe if queue 1 is inactive, which would make my
> > questions moot?
>
> The answer to your question is that idle queue do not consume capacity
> on the pipe they are associated with.  I have queue with weights 100
> (for VoIP), 20 (for interactive SSH, NTP) and 1 (everything else) and
> the "everything else" traffic can use the full capacity of the pipe
> with the other queues are idle.

This raises another question: how do the idle queues get shared?
Using the above sample configuration, if queue 2 is idle, does the
pipe get shared between queue 1 and queue 3 in proportions 10/11
and 1/11 respectively or 10/16 and 1/16 respectivly with the remaining
5/16 shared evenly between them?

Ian

--
Ian Freislich


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