[LARTC] Some questions remaining about TC

[Emmanuel SIMON <manu@host.fr>]

Hello everybody,

I try to work with TC for a little while in my study and there still are a few 
questions that I can\'t find any answer anywhere.

Firts about qdisc and classes:
 - What is exactly the difference between qdsic and class ? They are 
so \"intimately tied together\" that i\'m not sure not make the difference. Why 
can\'t we have a qdsic HTB with a class CBQ within or reverse.
 - We have classes but is there any heritage (i\'m not sure it is the right 
word) somewhere: between qdiscs, between classes or between qdiscs and classes.

About DSMARK, I don\'t understand the way it works:
 - What is the (mask, Value) ? What is it used for ?
 - Does it mark the packet or the structure in the kernel ?
 - If i can mark the packet, how is it done ? Can i put only \'minimize 
delay\', \'maximize throughput\' and so on, or can i put for exemple 10110111 if i 
want in the TOS field ?
 - Does it exist a howto only about DSMARK ?

Another subject not so far from LARTC:
Chapter 11 of the howto says we can modify the TOS with Iptables. I\'ve tried to 
change it with the table mangle and to set it to a value outside the TOS values 
(again). it failed (of course ?). After having modified the source code of 
iptable and netfilter and removing the check on the TOS values, it stille 
failed ! There is \"something\" in the IP stack that blocks me !! Does anyone 
know how to do that ???

I have read all that i found: howtos, memos of Werner Almersberger, Q/A of the 
list, books but these questions still remain (and maybe any other). So please, 
help.

thanks
Emmanuel

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