From: Chris Lewis (chrlewiscsco@gmail.com)
Date: Tue Jun 20 2006 - 10:39:26 ART
There is no need to multiply by 1.5.
Burst can never be expressed as a rate, it can only be expressed as a bit or
byte value.
The 1.5 figure comes from a general rule of thumb to help calculate the size
of burst, if you have been given the burst size, it is irrelevant. The
1.5figure is just a generalizationfor giving you a figure that will
help the
policer achieve line rate under normal conditions. If the traffic profile of
the load offered to the policer differes, the 1.5 figure differs. It is
probably best just to forget it as i know of only extremely rare situations
when you need to worry about tuning this.
I believe the original question was either written incorrectly, of the
person setting the question did not understand policing. Burst should only
be described as a burst or byte value. The only time you can really use
burst to define a rate is if you state that credit has been built up, which
is the only way you can use burst setings in policing.
Chris
On 6/20/06, Popgeorgiev Nikolay <nikolay.popgeorgiev@siemens.com> wrote:
>
> Koen,
>
> Can you explain better why with need to multiply with 1.5 ? I thouth there
> were some recommendations from cisco about the normal burst and max burst
> which have something to do with this 1.5 but can't remember well what was
> it about.
>
> I am for solution 2.
>
> Best,
> Nick
>
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Koen Zeilstra [mailto:koen@koenzeilstra.com]
> Sent: Tuesday, June 20, 2006 2:47 PM
> To: Maximus
> Cc: Cisco certification
> Subject: Re: Doubt in CAR : Rate limit
>
> if the b is lowercaps its bits so you should divide by 8. That give's you
> the burst size per timing interval. Not per second. So you have to convert
> the bps to a byte per timing interval value. I believe the timing
> interface for CAR is 1,5. So that makes 300000/8*1,5=56250.
>
> -> solution 3.
>
> Don't forget the "exceed-action drop".
>
> HTH
>
> Koen
>
> -----------------------
> Kerr's Three Rules for a Successful College:
> Have plenty of football for the alumni, sex for the students,
> and parking for the faculty.
>
> On Tue, 20 Jun 2006, Maximus wrote:
>
> | ok i am only confused on converting the normal and max burst
> |
> | i will give the three kind of answers which i got from pals... can
> somebody
> | tell me which one to go forward with..
> |
> | Qn again : the requiremenet is "traffic is limited to 8 Mbps, with a
> normal
> | burst size of 150kbps and an Max Burst size of 300kbps. traffic that
> | conforms is sent
> | with an IP precedence of 5. Traffic that does not conform is dropped. "
> |
> | Sol 1 :rate-limit output 8000000 150000 300000 conform-action
> | set-prec-transmit 5
> |
> | Sol 2 :rate-limit output 8000000 18750 37500 conform-action
> | set-prec-transmit 5
> |
> | 150000/8 = 18750
> | 300000/8 = 37500
> |
> | Sol 3 :rate-limit output 8000000 28125 56250 conform-action
> | set-prec-transmit 5
> |
> | (150000/8)*1.5 = 28125
> | (300000/8)*1.5 = 56250
> |
> |
> | On 6/20/06, Vishal Patel <vpatel@accessproviders.com.au> wrote:
> |
> | > In CAR command , the first figure i.e. 8 Mb in your case is in Bits
> per
> | seconds.
> |
> | Then the second figure is Normal burst which is number of Bytes.
> |
> | Then the third value is the Maximum Burst which is number of Bytes.
> |
> |
> |
> |
> | -----Original Message-----
> | From: nobody@groupstudy.com [mailto: nobody@groupstudy.com] On Behalf Of
> | Maximus
> | Sent: Tuesday, 20 June 2006 11:21 AM
> | To: Cisco certification
> | Subject: Fwd: Doubt in CAR : Rate limit
> |
> | sorry made a small typo... this is the exact config i have done
> |
> | hie all just a lil confusion
> |
> | the requiremenet is "traffic is limited to 8 Mbps, with a normal burst
> size
> | of 150kbps and an Max Burst size of 300kbps. traffic that conforms is
> sent
> | with an IP precedence of 5. Traffic that does not conform is dropped. "
> |
> |
> | rate-limit output 8000000 150000 300000 conform-action set-prec-transmit
> 5
> |
> | is my config rite ? the confision is in normal n max is it in bytes or
> | bits...somebody please lead me out...
> |
> |
> | regards,
> |
> | Max
> |
> |
> |
> | --
> | regards,
> |
> | Max
> |
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