From: Roberto Fernandez (rofernandez@us.telefonica.com)
Date: Wed Jul 05 2006 - 11:14:30 ART
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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