From: Pierre-Alex (paguanel@hotmail.com)
Date: Sat Jun 17 2006 - 14:07:09 ART
Koen asked said " to make sure there isn't a single bit extra being sent out
from interface f0/0" over 128 K.
To ensure this, it is important to set be to 0 otherwise, when there is no
activity, tokens will accumulate
and there will burst to 256K)
So I believe the answer should be:
shape average cir 128000 bc 16000 be 0
Pierre-Alex
----- Original Message -----
From: "Mienbaikebi Patani" <patmien@gmail.com>
To: "Koen Zeilstra" <koen@koenzeilstra.com>
Cc: <ccielab@groupstudy.com>
Sent: Saturday, June 17, 2006 6:25 PM
Subject: Re: limit traffic without police or rate-limit
> using the MQC command "shape peak" effectively fills both Bc and Be
> buckets
> at the begining of every Tc, and then effectively transmitting traffic
> worth Bc + Be at every Tc. So if you use the command "shape peak" you are
> effectively transmitting more than is expected depending on the Bc and
> the CIR you want to achieve. So the "shape average" is what will meet the
> requirements of not transmitting more than you want.
>
> For example I want CIR to be 128k and Tc is left at default of 125ms, and
> I
> do the following;
>
> shape peak cir 128000 bc 16000 be 16000
>
> The above setting effectively transmits Bc + Be (16000 + 16000 = 32000) at
> every interval. Considering the total rate for a period of 1000ms you are
> going to have 32000 X 8 = 256000(since we have 8 intervals of 125ms in
> 1000ms) which is effectively more than the CIR of 128k we want.
>
> But if we do the following for thesame values in the above example I
> stated;
>
> shape average cir 128000 bc 16000 be 16000
>
> The following will be the result;
>
> Assuming there is no period of inactivity, meaning that we effectively
> transmit Bc at every interval, the overall rate will be 16000 X 8 =
> 128000.
> This is because the value Be can only have tokens to transmit data when
> not
> all Bc value was used in prior Tc intervals. So if we do not have any
> interval of inactivity, then effectively the value Be will be equal to 0.
>
> Note: Be is only filled with Bc Tokens that were not used in some
> intervals
> when you use the command "shape average" but is effectively filled at the
> begining of every interval when we use the command "shape peak".
>
> To meet the requirements of the example I stated with the command "shape
> peak" I will rather do the following;
>
> shape peak cir 64000 bc 8000 be 8000
>
> Then I will be transmitting for every interval Bc + Be (8000 + 8000 =
> 16000), and then the overall rate becomes 16000 X 8 = 128000, which still
> meets the requirements of my example.
>
> If you take a look carefully at the output of the "show policy-map
> interface
> X" you will see the difference of the settings when you use the two
> commands. I don't have a router currently with me to get the outputs for
> you
> to see. You may check yourself to confirm.
>
> So you need to be careful with the values you set when using either
> commands.
>
> I hope this was informative to you.
>
>
> On 6/17/06, Koen Zeilstra <koen@koenzeilstra.com> wrote:
>>
>> Hi Group,
>>
>> Say I want to limit the amount of traffic to to a certain destination to
>> 128k. What would the best solution?
>>
>> Something like this?
>>
>> ip access-list ext TARGET
>> permit ip any host 10.0.0.1
>> !
>>
>> class-map LIM128
>> match access-group name TARGET
>> !
>>
>> policy-map QOS
>> class LIM128
>> shape peak 12800
>> !
>>
>> int f0/0
>> service-policy output QOS
>> !
>>
>>
>> Does this make sure there isn't a single bit extra being sent out from
>> int
>> f0/0?
>>
>> Is shape peak here better or shape average if no more requirements are
>> mentioned.
>>
>> thanks,
>>
>> Koen
>>
>>
>> -----------------------
>> Math is like love -- a simple idea but it can get complicated.
>> -- R. Drabek
>>
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