LARTC - May 2002 - cbq (root class) rate problem

From where the cbq classes borrow bandwith? (parent or sibling)

If the parent is rate at 50kbit the leaf classes should not get more
bandwith than the parent?

Why does the classes (with root class as parent) borrow bandwith beyond
the rate set when cqb is created?

CBQ on 10Mbit Ethernet
2 clasess 25kbit on each
borrow and sharing both

When I create the cqb qdisc it create a root class with the handle 10:0
I set the root class to rate at 50kbit

Then I create to classes whith 10:0 as the parent

Both classes borrow bandwith beyond the 50kbits

tc qdisc  add dev eth0 root handle 10:0 cbq bandwidth 10mbit avpkt 1000
cell 8 rate 50kbit

tc class  add dev eth0 parent 10:0 classid 10:10 cbq bandwidth 10mbit
rate 25kbit allot 1514 cell 8 maxburst 20 avpkt 1000 sharing borrow

tc class  add dev eth0 parent 10:0 classid 10:11 cbq bandwidth 10mbit
rate 25kbitallot 1514 cell 8 maxburst 20 avpkt 1000 sharing borrow


I did a workaround by creating an extra class with root class as parent
and isolated,bounded


But I don''t like to have extra classes just becuse I can control root
class.

tc qdisc  add dev eth0 root handle 10:0 cbq bandwidth 10mbit avpkt 1000
cell 8

tc class  add dev eth0 parent 10:0 classid 10:1 cbq bandwidth 10mbit
rate 50kbit allot 1514 cell 8 maxburst 20 avpkt 1000 isolated bounded

tc class  add dev eth0 parent 10:1 classid 10:10 cbq bandwidth 10mbit
rate 25kbit allot 1514 cell 8 maxburst 20 avpkt 1000 sharing borrow

tc class  add dev eth0 parent 10:1 classid 10:11 cbq bandwidth 10mbit
rate 25kbitallot 1514 cell 8 maxburst 20 avpkt 1000 sharing borrow

> I did a workaround by creating an extra class with root class as parent
> and isolated,bounded
>
>
> But I don''t like to have extra classes just becuse I can control
root
> class.
>
> tc qdisc  add dev eth0 root handle 10:0 cbq bandwidth 10mbit avpkt 1000
> cell 8
>
> tc class  add dev eth0 parent 10:0 classid 10:1 cbq bandwidth 10mbit
> rate 50kbit allot 1514 cell 8 maxburst 20 avpkt 1000 isolated bounded
>
> tc class  add dev eth0 parent 10:1 classid 10:10 cbq bandwidth 10mbit
> rate 25kbit allot 1514 cell 8 maxburst 20 avpkt 1000 sharing borrow
>
> tc class  add dev eth0 parent 10:1 classid 10:11 cbq bandwidth 10mbit
> rate 25kbitallot 1514 cell 8 maxburst 20 avpkt 1000 sharing borrow
This is the way you should do it.  That extra class is no problem.  You can 
remove the sharing and borrow parameter if you want.  They are on by default.

Also provide a weight parameter (I take weight = rate/2) and attach the 
filters to the root qdisc and point them direclty to the end class.

Stef

-- 

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
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