From: ccie_for_sure@comcast.net
Date: Wed Jul 05 2006 - 12:10:23 ART
I would assume if a question says calculate 16k normal burst using the default
burst interval you are correct (CCO) but if it says your normal burst is 16k does it want to see 16k/8 or 16k/8 * 1.5? Just like FR, if CIR is 128k using the default
interval */8 or .125 do you need BE or just BC? or configure some made up bandwidth under an interface to get the BE values? This is what you have to askyourself when approaching questions like these. If something is not there why assume you need it? But it is easy to read to much into a question when you have knowledge of the techonology, that is why I said, the proctor is your best friend the day of the lab so know how to approach him/her and ask good questions, they will give you good direction when they see you know what
you are talking about.
D.
-------------- Original message ----------------------
From: "Roberto Fernandez" <rofernandez@us.telefonica.com>
> Friends,
>
> My thoughts on the subject,
>
> Maybe, I'm overlooking something, or looking too much into it...
> following the exact wording by Stavros "need to rate limit to a maximum
> of 256 Kbps and normal burst to 8kbps" NOTE 8kbps (per second)... using
> the 1.5 second multiplier in the formula at DocCD, those 8kbps would
> translate into 1500 bytes for the 1.5 seconds interval. 1500 is the
> minimum value, and the one which the IOS would put if you try a lesser
> one.
>
> Maybe in this question the hidden issue it is not the Normal Burst but
> the Extended Burst which would be have to be set to 3000, instead of
> 2000 which would be the first option following the 1000 bytes so:
>
> rate-limit input 256000 1500 3000 conform-action transmit exceed-action
> drop would be the best answer (IMH)
>
> opposed to
>
> rate-limit input 256000 1500 2000 conform-action transmit exceed-action
> drop
>
> which would have the right Normal Burst (according to my reasoning), but
> a wrong Extended Burst (according to the formula at DocCD.
>
>
> ---DocCD---
>
> CAR embodies a rate-limiting feature for policing traffic. When policing
> traffic with CAR, Cisco recommends the following values for the normal
> and extended burst parameters:
>
> normal burst = configured rate * (1 byte)/(8 bits) * 1.5 seconds
>
> extended burst = 2 * normal burst
>
> With the listed choices for parameters, extensive test results have
> shown CAR to achieve the configured rate. If the burst values are too
> low, then the achieved rate is often much lower than the configured
> rate. "
>
>
> Best Regards,
> Roberto
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> ccie_for_sure@comcast.net
> Sent: Tuesday, July 04, 2006 3:56 PM
> To: Chris Lewis; Aaron Pilcher
> Cc: Stavros Filargyropoulos; Cisco certification
> Subject: Re: Rate-limit
>
> Just a note to remember CAR and Policer are interchangable (read
> networkers 2003 and 2005 preso) you as a CCIE should solve the question
> being asked. So this is not and NDA issue at all but a questions that is
> asking " how do I resolve a question when the techology asked but does
> not meet title questions.
>
> If you know the techology then there is more then one way to solve the
> questions and I assume that is the answer and no one can help you with
> that but experience :-)
>
> D
> -------------- Original message ----------------------
> From: "Chris Lewis" <chrlewiscsco@gmail.com>
> > Putting aside the NDA issue for amoment, as I don't think that this
> will
> > make or break someone's attempt.
> >
> > burst is in bytes, not bits per second. If you have to configure 8000
> bits
> > as a burst, that is clearly 1000 bytes. If you configure that on a
> default
> > ethernet interface, it does not make sense as one maximally sized
> packet is
> > greater than 1000 bytes. So reduce the maximum size of a packet on
> that
> > segment if the question asks you to set a burst of 8000 bits.
> >
> > Chris
> >
> >
> > On 7/4/06, Aaron Pilcher <apilcher@itgcs.com> wrote:
> > >
> > > Why wouldn't policing work? But yes, I came out with the same Bc of
> 1000.
> > >
> > > class-map match-all TEST
> > > match any
> > >
> > > policy-map TEST
> > > class TEST
> > > police 256000 bc 1000
> > >
> > > interface GigabitEthernet0/1
> > > service-policy output TEST
> > >
> > > Rack1R4#sh policy-map
> > > Policy Map TEST
> > > Class TEST
> > > police 256000 bc 1000
> > > conform-action transmit
> > > exceed-action drop
> > >
> > >
> > > That said, I noticed when I make a type on a FastEthernet interface
> that
> > > it
> > > gave me an error for the Bc. I used "2560000 bc 1000" accidentally
> and it
> > > increased the Bc to 1280.
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > > Stavros Filargyropoulos
> > > Sent: Monday, July 03, 2006 10:20 PM
> > > To: Cisco certification
> > > Subject: Rate-limit
> > >
> > > Hi there, I just took my lab days ago, and I failed once again, 2nd
> time
> > > and
> > > counting..
> > > Question here,
> > > I need to rate limit to a maximum of 256 Kbps and normail burst to
> 8kbps
> > > using CAR
> > > Bits per second = 256000 and Normal burst = 1000 are correct ??
> > > But when I configure this I get this error
> > > Illegal normal burst size
> > > Increasing normal burst size to 1500
> > >
> > > Please help with this, it sucks
> > > Thanks
> > > *Stav
> > >
> > > *
> > >
> > >
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> >
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