[LARTC] Classes and qdiscs

[LARTC] Classes and qdiscs

[S Mohan]

I've been reading the posts on classless queuing and classes/qdisc
combinations. Both Martin and Stef mentioned that one class can have
more than one qdisc attached.

The way I had understood queue disciplines was as follows:

1. A class has a qdisc to regulate traffic under limit e.g htb/tbf....
2. A tier in the hierarchy has a qdisc attached for sharing of spare
bandwidth not utilized by one or more classes amongst the others in the
same tier.

Or would it be correct to say that each class has a qdisc that
distributes its spare bandwidth to others in the same level in the
hierarchy? Does it mean that if I have SFQ for one class and have not
attached SFQ to the other two classes at the same level, the other two
classes would get even distribution of bandwidth not utilized by the
first class?

Can a scenario be drawn up as to why we would need more than two qdiscs
for a class (one for under limit and one for spare).

Bye
Mohan 

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Re: [LARTC] Classes and qdiscs

[Stef Coene]

On Thursday 13 March 2003 01:57, S Mohan wrote:
> I've been reading the posts on classless queuing and classes/qdisc
> combinations. Both Martin and Stef mentioned that one class can have
> more than one qdisc attached.
No.  One class can has 1 qdiac attached.  But there are qdiscs with multiple 
classes and you can add a qdisc to each of these classes.

> The way I had understood queue disciplines was as follows:
>
> 1. A class has a qdisc to regulate traffic under limit e.g htb/tbf....
Not really.  The qdisc is only responsible for sending the traffic that 
belongs to that class.

> 2. A tier in the hierarchy has a qdisc attached for sharing of spare
> bandwidth not utilized by one or more classes amongst the others in the
> same tier.
>
> Or would it be correct to say that each class has a qdisc that
> distributes its spare bandwidth to others in the same level in the
> hierarchy? Does it mean that if I have SFQ for one class and have not
> attached SFQ to the other two classes at the same level, the other two
> classes would get even distribution of bandwidth not utilized by the
> first class?
Classes are responsible for managing the traffic.  Each class sholds a part of 
the total traffic.  Unused bandwidth can be shared amongs the differenc 
classes.
If you want to understand how traffic is managed between classes, forget about 
the qdiscs.  Just think about the classes.  The qdiscs are only responsible 
for sending the traffic.  The amount of traffic is regulated by the 
configuration of the classes.

Stef


-- 

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.oftc.net

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[LARTC] classes and qdiscs

[Marcus Fritzsch]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hello everybody!

I am wondering, whether it is possible to have qdiscs and classes as
childs of a class or not.

take the following example:

~ ,-----
~ |                class 1:1
~ |               /         \
~ |             /             \
~ |           /                 \
~ |      class 1:10          qdisc 11:
~ |      /        \
~ |    ...        ...
~ `-----

does this makes any sense?



greetings from germany, Marcus

- --
~                                          s(c,t){return isalpha(c)&&t?/*
Marcus Fritzsch <marcus.fritzsch@gmx.net>  ICQ:53118621  WWW:fritschy.de
~  GnuPG: gpg --keyserver sks.keyserver.penguin.de --recv-keys 98A1D365
*/s(65-c&&97-c?--c:c+25,--t):c;}main(){for(;;)putchar(s(getchar(),13));}


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Re: [LARTC] classes and qdiscs

[Andy Furniss]

Marcus Fritzsch wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Hello everybody!
> 
> I am wondering, whether it is possible to have qdiscs and classes as
> childs of a class or not.
> 
> take the following example:
> 
> ~ ,-----
> ~ |                class 1:1
> ~ |               /         \
> ~ |             /             \
> ~ |           /                 \
> ~ |      class 1:10          qdisc 11:
> ~ |      /        \
> ~ |    ...        ...
> ~ `-----
> 
> does this makes any sense?

You can do a queue within a queue with htb see section 6 -

http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm

You will need to double up on filters - ie. you can't filter directly 
from root queue to subclass of child queue.

Andy.

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Re: [LARTC] classes and qdiscs

[Andy Furniss]

Andy Furniss wrote:

> 
> You can do a queue within a queue with htb see section 6 -
 >
 > http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm

Oops it's not a queue within a queue. I just tried it, but it may be all 
you need - depending what you need to do that for :-)

Andy.
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