The forumulas for calculating the Bc and Be for policing are how you have
defined, them but I would be careful with the use of the term "Tc" when
dealing with policing.  Tc is generally a term that applies to traffic
shaping and not traffic policing.  Why?  What does Tc do for us?  With a
shaper, Tc is a static defined interval of time.  As you know, each Tc
interval we get to add Bc tokens to the bucket to use.  Traffic policing
does not work the same way, contrary to popular belief. With traffic
policing, the token bucket is refreshed based on a function of 2 things:
The CIR value and the amount of time passed since the last packet was
received.  It has nothing to do with Tc.

My point is simply that Tc is not involved with the calculations of traffic
policing, as it is a concept that applies to traffic shaping.

On Sun, Apr 22, 2012 at 12:32 PM, Kingsley Charles <
[email protected]> wrote:

> Hi all
>
> The following is how we calculate Bc for QoS MQC policing and TCP
> rate-limiting. Now for ZPF policing, which formula should be used. I need
> Cisco doc for confirmation.
>
>
> Policing
> ========
>
> Tc = 0.25 secs
>
> BC = CIR/8 * 0.25 = CIR/32
>
> Be = Bc, if not specified
>
>
> TCP Rate-limiting
> =============
>
> Tc = 1.5 secs
>
> BC = CIR/8 * 1.5
>
> BE = 2 BC
>
>
> With regards
> Kings
>
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-- 
Regards,

Joe Astorino
CCIE #24347
http://astorinonetworks.com

"He not busy being born is busy dying" - Dylan
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