From: Leigh Harrison (ccileigh@gmail.com)
Date: Mon Sep 19 2005 - 13:25:41 GMT-3
All,
Having had a damn good read through the doc CD, I'd like to retract my
earlier mail, and class my writing as total crap!!
Wish me luck on Thursday....
LH
simon hart wrote:
>Hi All,
>
>I would welcome comments on this task within the IE workbook. I think that
>the question and answer may be incorrect,
>
>The task itself is to change various CAR statements into MQC. The problem I
>see here is that CAR and MQC have different policing algorithms and thus to
>mimic each statement is extremely diffilcult.
>
>One is asked to achieve the following
>
>rate-limit input access-group 101 128000 2000 2000 conform-action transmit
>exceed-action set-prec-transmit 0
>
>The answer given for the MQC statement is as follows
>
>police cir 128000 bc 2000 be 2000
>conform-action transmit
>exceed-action set-prec-transmit 0
>
>Now I believe this answer to be wrong for the following reasons. When the
>bc and be are equal within CAR there is no burst, thus no exceed action.
>Although the CLI for CAR will accept the 'exceed-action set-prec-transmit 0'
>there is in fact no burst and thus no exceed action.
>However when entering the command within MQC we have a problem if we mimic
>the CAR statements. Because MQC uses a single rate three colour marker it
>has two discrete token buckets. By setting bc and be we are setting the
>values for each token bucket and hence enabling an exceed action. Therefore
>we are allowing a burst action that will set the precedence of 0, however
>the CAR statement does not allow that.
>
>I believe the correct answer would be
>
>police cir 128000 bc 2000
>conform-action transmit
>exceed-action drop
>
>
>One is also asked to perform the following
>
>rate-limit input access-group 102 256000 4000 8000 conform-action transmit
>exceed-action set-prec-transmit 0
>
>The answer given for this in MQC is:
>
>police cir 256000 bc 4000 be 8000
>conform-action transmit
>exceed-action set-prec-transmit 0
>
>For similar reasons that I gave above I believe that this answer is also
>incorrect. I believe that the correct answer should be
>
>police cir 256000 bc 4000 be 4000
>conform-action transmit
>exceed-action set-prec-transmit 0
>violate-action drop
>
>The CAR statement implies a burst of 4000 (the difference between 4000 and
>8000), therefore within MQC bc and be should be 4000 a piece. In addition
>one has to create a violate-action otherwise the circuit will never be
>limited to an average of 256000 as the exceed action will be used on all out
>of contract traffic.
>
>Other views most welcome
>
>Simon Hart
>
>
>
>
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