Ok, that´s great. I have a much better idea now.
However I have a doubt on [1]. When packets arrive to an HTB filter, it
first checks to see if there are ctokens available. How come if there are,
it then checks for tokens instead of just dequeuing at full speed. And if
there are none: shouldn´t it THEN check for tokens instead of discarding
right away?
Also, could you give me an advice or reference on the following?
I need a child class to allow passage to a video stream that I KNOW has mean
X kbps and seldom peaks of Y kbps and T seconds. Would the best way be to
just configure mean=X, ceil=Y? Or should I configure mean=ceil=X and
calculate a cburst that´ll allow passage of the peaks? Or maybe a third
option.
----- Original Message -----
From: "Martin A. Brown" <mabrown-lartc@xxxxxxxxxxxxxx>
To: "VideoIP" <videoip@xxxxxxxxx>
Cc: "lartc" <lartc@xxxxxxxxxxxxxxx>
Sent: Wednesday, July 13, 2005 2:14 AM
Subject: Re: HTB: ¿how do burst/cburst work exactly?
Hello,
: I´ve read all the definitions of burst and cburst and I´ve tried
: playing with the parameters and graphing the output of the filter
: to see its effects, but STILL I can´t figure out how the
: parameters work exactly.
:
: Could anyone give a better explanation than the manpage?
Have you tried Stef's site? He has a good page [0] that talks about
the various tests he did while experimenting with HTB burst and
cburst parameters?
Some time ago, I took a stab at creating a visual representation [1]
of a hypothetical HTB configuration [2]. In order to understand
when cburst is used, look for the diamond-shaped boxes in the
diagram which talk about tokens and ctokens.
Every HTB class has two buckets.
rate bucket is of burst size, traffic uses tokens
ceil bucket is of cburst size, traffic uses ctokens
My diagram may give you the framework to understand exactly how they
are used if it's still unclear to you, but Stef's site will give you
much better detail on the results of using burst and cburst. Of the
scenarios he describes, I like the results of Test 7 the best. The
only guideline that struck me after reading his results was to
prefer burst and cburst usage on parent classes.
Good luck,
-Martin
[0] http://www.docum.org/docum.org/tests/htb/burst/
[1] http://linux-ip.net/traffic-control/htb-class.png
[2] http://linux-ip.net/traffic-control/diagram.html
--
Martin A. Brown --- Wonderfrog Enterprises --- martin@xxxxxxxxxxxxxx
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