limit traffic without police or rate-limit
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” | To: “Koen Zeilstra” | Cc: | 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 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 | > > | > > _______________________________________________________________________ | > > Subscription information may be found at: | > > http://www.groupstudy.com/list/CCIELab.html | > | > _______________________________________________________________________ | > Subscription information may be found at: | > http://www.groupstudy.com/list/CCIELab.html | > | > | > — | > No virus found in this incoming message. | > Checked by AVG Free Edition. | > Version: 7.1.394 / Virus Database: 268.9.0/368 - Release Date: 6/16/2006 | | _______________________________________________________________________ | Subscription information may be found at: | http://www.groupstudy.com/list/CCIELab.html |
Category: CCIE Study
