[LARTC] tc questions

[Andy Furniss]

Alejandro Ramos Encinosa wrote:
> Hi to all of you!!!
> 
> I am a Computer Science student trying to do the pre-grade thesis. I am trying 
> to develop a free software tool to help administrators to control the 
> traffic. Right now this tool is based on tc and iptables.
> I am having some problems trying to understand tc and tc examples:
> - Why in almost every list of tc rules based on htb class, there is a "tc 
> qdisc dev ... root ... htb default ..." as a root node? Is it mandatory to 
> work with htb class?
> - I understood that every class node has its own qdisc attached (fifo by 
> default, right?). If that is the case, why when I do "tc qdisc show ..." it 
> JUST shows me those qdisc I explicitly attached to classes without any child 
> class?
> - What should I expect if I run something like this?
> 
> tc qdisc add dev eth0 root handle 1: htb default 10
> tc class add dev eth0 parent 1: classid 1:1 htb rate 100mbit
> tc class add dev eth0 parent 1:1 classid 1:10 htb rate 90mbit
> tc class add dev eth0 parent 1:1 classid 1:20 htb rate 1kbit
> tc class add dev eth0 parent 1:20 classid 1:21 htb rate 10mbit
> 
> I guessed the traffic redirected to 1:21 should have 1kbit of rate at most 
> (because of its parent 1:20), but when I ran this, I got a higher rate 
> (because of the 10mbit rate, I guess). Why? Shouldn't parent classes restrict 
> children's rate?
> 
> Thanks in advance. Regards, Ale.
> 

In addition to what Christian said - have you seen the docs on the htb 
homepage -

http://luxik.cdi.cz/~devik/qos/htb/

and Steph Coene's work -

http://www.docum.org

Andy.