From: Koen Zeilstra (koen@koenzeilstra.com)
Date: Sun Jun 18 2006 - 07:13:33 ART
When would you use
"shape average 128000" and when "shape cir 128000".
ie. what would be the hints in the question that point to either solution?
thanks,
Koen
-----------------------
... bleakness ... desolation ... plastic forks ...
On Sat, 17 Jun 2006, Pierre-Alex wrote:
| 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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