Re: [LARTC] SEPARATING VOIP AND SURFING

[Jason Boxman <jasonb@edseek.com>]

On Monday 15 November 2004 20:06, Ricardo Soria wrote:
<snip>
> Dear Andy:
>
> Very thanks for your answer.  However, I need a little
> bit more extended explanation.
>
> First, you say that I should "back off more from link
> speed - total ceils to about 80% and share that
> between interactive and bulk".  So, do you mean that
> if I have a total 512Kbit link, and 2 child classes, I
> should not divide the whole 512kbit between the 2
> classes, but, I should only divide 410kbit between
> them, and share the remaining 102kbit between them??
> Or do you mean I should only consider 410kbit as the
> whole link capacity??

I think he meant to treat your link as if it were only 410kbit.  With some 
testing you can verify just how close to 100% of your advertised capacity you 
can get, but 80% is often a good place to start.

> Second, you say that I should not use SFQ as a
> sub-qdisc, because of the lenght of the queue, being
> it ESFQ (new for me) a better choice.  But later, you
> say I should use SFQ for bulk traffic (I think you
> refer surfing as "bulk", and voip as "interactive").
> So, should I use SFQ for bulk classes and ESFQ for
> interactive classes ??  Or, should I use ESFQ for all
> leaf classes??  Or, should I use ESFQ for bulk classes
> and default (pfifo, I think) for interactive classes??

I am curious about this myself.  I placed a default sfq qdisc with the 128 
queue default on a p2p class that had a rate of 144kbit and it routinely 
spiked to about 150kbit several times a second.  If I use pfifo with a queue 
length of 10 I find my utilization for that class at around 146kbit instead.  
Is it the queue length causing this behavior?

-- 

Jason Boxman
Perl Programmer / *NIX Systems Administrator
Shimberg Center for Affordable Housing | University of Florida
http://edseek.com/ - Linux and FOSS stuff

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