Re: Policing and Tc

So what are you saying here that Policing uses a scheduler for single rate
polcing but a packet based approach for dual rate policing?

Cheers,

Garth

On Tue, Mar 2, 2010 at 1:20 AM, karim jamali <karim.jamali_at_gmail.com> wrote:

> Hi Garth,
>
> This is from a previous email I sent to groupstudy and was a result of an
> explanation of Petr Lapukhov and Joe Astrino. I am truly thankful to both
> for sharing their knowledge.
>
> This is the email I sent which is sort of a summary:
>
> Dear Gents,
>
> I would like to thank Petr & Joe for such a wonderful knowledge sharing.
> The main point of discussion as I understand is how the token bucket is
> updated with policing:
>
> 1)Scheduler Approach which Petr mentioned relies on adding a number of
> packets every scheduling interval (without having to do anything with the
> way packets arrive and inter-arrival time).
>
> 2)Packet based approach: which relies on the inter-arrival time of packets
>
> Specifically, the token arrival rate is calculated as follows:
> (time between packets<which is equal to t-t1>* policer rate)/8 bits per
> byte Looking at the formulas that Joe used from Cisco's website:
>
> Tc(t) = min(CIR * (t-t1) + Tc(t1), Bc)
> Tp(t) = min(PIR * (t-t1) + Tp(t1), Be)
>
> It seems that the either the Packet based approach or the Scheduler based
> approach could be used (based on the minimum). We are comparing the number
> of tokens currently in the bucke (at time t): addition of what we have put
> CIR * (t-t1) as well as what was already in the bucket at time t1. We
> compare this value to the Bc. This comparison will lead to using either
> packet or scheduled mode.
>
> Once again,Petr & Joe can't thank you enough!
>
> Best Regards,

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Received on Tue Mar 02 2010 - 11:56:00 ART