From: Jared Scrivener (jscrivener@ipexpert.com)
Date: Wed Mar 18 2009 - 12:57:57 ART
There was a thread on this a month or so ago that become pretty detailed.
I'd suggest checking it out.
Cheers,
Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP
Technical Instructor - IPexpert, Inc.
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: jscrivener@ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of M
Lab
Sent: Wednesday, 18 March 2009 8:57 AM
To: Vijay Karanth
Cc: Salahaddin Elshekeil; Cisco certification
Subject: Re: Formula for BC and BE
Here is my understanding:
Bc = CIR/Tc
Be = (AR/TC) - Bc
Default timing (Tc) is 125ms. (8*125ms = 1000ms or 1 second)
So if you had a CIR (target rate) that was 32000 you would have a Bc of
4000.
Be would be the result of what is leftover based on the actual speed of the
line or AR for that timing interval. In this example if the actual line rate
was 64000 you would have 4000 left over for Bc.
I probably didn't do a very good job of explaining, but that's how I
understand it. I just like to answer because it helps to solidify my own
understanding.
Maybe Scott or Narbik will jump in. They can explain this in a way that
makes sense the first time you read it.
Hopefully that was correct and helps!
On Wed, Mar 18, 2009 at 6:18 AM, Vijay Karanth
<vijay.karanth@gmail.com>wrote:
> Great, thanks.
>
> Can you help with an example: say if we have to rate limit it to 128kbps
> and
> allow it to bust 1/4th of the committed rate.
>
> Regards,
> Vijay Karanth
>
>
> 2009/3/18 Salahaddin Elshekeil <salah.elshekeil@gmail.com>
>
> > *
> >
> > CIR = Bc X 1000/Tc
> >
> > Bc = CIR X Tc/1000
> >
> > Tc = Bc/CIR X 1000
> > **
> >
> > Be = (AR b CIR) X Tc/1000
> > *you can use this
> >
> > On Wed, Mar 18, 2009 at 3:09 PM, Vijay Karanth
> <vijay.karanth@gmail.com>wrote:
> >
> >> Hi,
> >>
> >> I'm looking at the formula for BC and BE if we know CIR. And I assume
> that
> >> it's the same formula for traffic-shaping and for policing/shaping.
> >>
> >> Regards,
> >> Vijay Karanth
> >>
> >>
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> >>
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>
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