RE: QOS Formulas

From: Scott Morris (smorris@internetworkexpert.com)
Date: Fri Jan 02 2009 - 11:12:56 ARST


The rate-limit command isn't tied to a time interval in the same fashion
that traffic-shaping it. In traffic shaping, your CIR and Bc are used to
derive the interval (moving target).

In the rate-limit command, samples are taken every one second and averaged
over a 5-second period of time. So it's more of a statistical analysis than
any interval-based specific function.

HTH,

Scott

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
CiSco Champ
Sent: Friday, January 02, 2009 6:33 AM
To: ccielab@groupstudy.com
Subject: QOS Formulas

Hi,

Qos parameters calculation like Bc and Be, are there different formulas to
calculate for FRTS and rate-limit. I am confused like one formula to
calculate Bc is

Bc = CIR * Tc/1000 and to calculate Be is Be = (AR - CIR) * Tc/1000

other formula i can see on cisco doc is

normal burst = configured rate * (1 byte)/(8 bits) * 1.5 seconds
extended burst = 2 * normal burst
Can somene explain when to use one and when other formula, I really
appreciate

Regards

Blogs and organic groups at http://www.ccie.net



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