Hello,

I've just recently started to use IMQ and I got puzzled after seeing the
imq usage example on the linuximq.net site:

It was something like this:

tc qdisc add dev imq0 handle 1: root htb default 1
tc class add dev imq0 parent 1: classid 1:1 htb rate 1mbit
tc qdisc add dev imq0 parent 1:1 handle 10: htb default 5
tc class add dev imq0 parent 10: classid 10:1 htb rate 256kbit burst 30k
prio 1

and I tried the following (like in the classic htb examples from lartc)
and it worked:

tc qdisc add dev imq0 handle 1: root htb default 99
tc class add dev imq0 parent 1: classid 1:1 htb rate 1mbit
tc class add dev imq0 parent 1:1 classid 1:10 htb rate 100kbit
tc class add dev imq0 parent 1:1 classid 1:99 htb rate  900kbit

tc qdisc add dev imq0 parent 1:10 handle 100 sfq perturb 10
tc qdiisc add dev imq0 parent 1:99 handle 9 sfq perturb 10

Can someone help me understand the first example and why would someone
create a root qdisc that redirects all traffic to a class and then
instead of attaching child classes to that class,  one would create a
qdisc associated with that class and then attach the child classes to it.

Mihai, there is no need to make it like that:
qdisc->class->qdisc->client_classes ... this is just an example, not
something that have to be followed.

A possible use for a setup like that would be to have another qdisc
child from 1:1 using CBQ for example, not HTB, and then child classes to
attach clients.

Regarding queue disciplines and classes, IMQ devices have no diferences
from common ethX devices. The same structures and rules apply.

So, don't get lost on it and keep doing it the way you use to. Anyway
I'll simplify that example.

You just should pay attention to the iptables stuff to redirect your
traffic to the IMQ device.

Good luck!

Andre



Mihai Tanasescu wrote:
> Hello,
>
> I've just recently started to use IMQ and I got puzzled after seeing the
> imq usage example on the linuximq.net site:
>
> It was something like this:
>
> tc qdisc add dev imq0 handle 1: root htb default 1
> tc class add dev imq0 parent 1: classid 1:1 htb rate 1mbit
> tc qdisc add dev imq0 parent 1:1 handle 10: htb default 5
> tc class add dev imq0 parent 10: classid 10:1 htb rate 256kbit burst 30k
> prio 1
>
> and I tried the following (like in the classic htb examples from lartc)
> and it worked:
>
> tc qdisc add dev imq0 handle 1: root htb default 99
> tc class add dev imq0 parent 1: classid 1:1 htb rate 1mbit
> tc class add dev imq0 parent 1:1 classid 1:10 htb rate 100kbit
> tc class add dev imq0 parent 1:1 classid 1:99 htb rate  900kbit
>
> tc qdisc add dev imq0 parent 1:10 handle 100 sfq perturb 10
> tc qdiisc add dev imq0 parent 1:99 handle 9 sfq perturb 10
>
> Can someone help me understand the first example and why would someone
> create a root qdisc that redirects all traffic to a class and then
> instead of attaching child classes to that class,  one would create a
> qdisc associated with that class and then attach the child classes to it.
>
>
>
>
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>
>