Re: [LARTC] HTB questions

From: Stef Coene <stef.coene@docum.org>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] HTB questions
Date: Sat, 14 Sep 2002 08:49:12 +0000	[thread overview]
Message-ID: <marc-lartc-103199345204506@msgid-missing> (raw)
In-Reply-To: <marc-lartc-102338445800500@msgid-missing>

On Saturday 14 September 2002 08:56, curt brune wrote:
> Hello,
>
> I have a number of questions re: HTB
>
> * Traffic Simulator
>
> I saw the traffic simulator, ethloop -- very clever.  I was wondering,
> however, how to simulate traffic destined for specific ports ?  In the HBT
> HOWTO there are gnuplots of traffic destined for different ports.
I never used ethloop myself, but I think it uses flowid's.  So if you create a 
htb setup with classes and filters, you can use the u32 filter to match 
packets with different ports.  Ethloop will generate the traffic in the 
flowid's you configured it for.

Or take a look at the P option :

P Number. Priocode set by setsockopt(sock,SOL_SOCKET,SO_PRIORITY,...). It is 
very convenient way to test qdisc because majority of classfull qdisc will 
use classid stored in priority field. To say that this flow should go to 
class 3:4f use P 0x3004f. This way you need no filters.

> * Low rate shaping
>
> My maximum uplink is 384kbits/sec .  I plan to shape HTTP,SMTP and other
> protos to some fraction of the maximum.  Are there any special steps when
> shaping to these low rates ?  I saw most of the examples are in the 5 to 10
> mbit/sec range, roughly 30 times higher than what I plan to do.
If you have class with very different rates, it's possible you can get 
warnings about quantum.  You can ignore them, but it's better fix it.  To be 
short, quantum = rate / r2q with r2q = 10 by default.  
And MTU (1500) < quantum < 60.000.
Quantum is the number of bytes a class my send IF 2 or more classes are 
fighting for bandwidth from the same parent.  You can overrule r2q when you 
add the htb qdisc and/or you can overrule quantum when you add a htb class.

Stef

-- 

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

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