netdev - Re: [Announce] LARTC wiki available

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Message-ID: <Pine.LNX.4.64.1206030343400.3122@ask.diku.dk>
Date:	Sun, 3 Jun 2012 04:36:11 +0200 (CEST)
From:	Jesper Dangaard Brouer <hawk@...u.dk>
To:	Andy Furniss <andyqos@...sn.org>
Cc:	Julien Vehent <julien@...uxwall.info>,
	Niccolò Belli <darkbasic@...uxsystems.it>,
	lartc@...r.kernel.org, netfilter@...r.kernel.org,
	Linux Networking Developer Mailing List 
	<netdev@...r.kernel.org>, brouer@...hat.com
Subject: Re: [Announce] LARTC wiki available

On Sat, 2 Jun 2012, Andy Furniss wrote:

> Julien Vehent wrote:
>>  On 2012-06-01 12:42, Niccolò Belli wrote:
>> >  http://lartc.org is alive and kicking and there is no need for
>> >  another
>> >  wiki anymore. I'd like to thank both Bert and Carl-Daniel.
>> > 
>> >  Niccolò
>> > 
>>
>>  Very cool !
>>  I'll try to find some time and move over some of the content I have
>>  here:
>>  http://wiki.linuxwall.info/doku.php/en:ressources:dossiers:networking:traffic_control
>
> A couple of things that stand out after skimming through.
>
> DSL - Jeesper's overhead as noted in the comments is not 5 and anyway I think 
> his good work has now been superseded by stab as it allows for negative 
> overheads, which his did not.

Thanks for the credits :-)

Its been a while since I looked at that code.  I think, the 5 bytes might 
ref to the ATM header 5 + 48 = 53 bytes the ATM cell size.  But 5 is not 
used as overhead.

The linklayer ATM hack is to adjust the rtable array, that the kernel uses 
for lookups.  The problem is that the rtable array only have an 8 bytes 
"resolution" (well depend on cell_log), thus to get this aligned, I use 
the ATM payload size of 48, when populating the rtable array.  Then 
when storing the "data" I the rtable array I use *53 byte ATM cell size.

> man tc-stab has clear and good explanations and examples.

Good to see some documentation on stab, I always found it difficult to 
use.

Cheers,
   Jesper Brouer

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