From: Sameh El Tawil (eltawil@free.fr)
Date: Sat Jan 08 2005 - 17:52:02 GMT-3
I found a post on the internetwork Expert support forum to the effect that
the drop keywords with the ICMP class have been missed out (typo). So we can
ignore point1. I still do not have answers for points 2 - 4. I hope I am not
getting it all wrong :-(
Regards,
Sameh
----- Original Message -----
From: "Sameh El Tawil" <eltawil@free.fr>
To: <ccielab@groupstudy.com>
Sent: Saturday, January 08, 2005 11:02 AM
Subject: IE lab13 task 9.1 (CAR to MQC translation)
> I have some questions about this solution:
>
> 1- In class ICMP the solution does not specify conform/exceed action. In
my
> lab this gives a default conform-action transmit and a default
exceed-action
> drop. How could this translate the original rate-limit statement having
both
> conform and exceed actions as drop?
>
> 2- In class UDP I have a question that may be considered "cosmetic" : As
far
> as i understand if no violate-action is specified, a single-token bucket
> algorithm will be used, which means that the specified Be is not used
towards
> any calculation. Do you agree that we can leave out the Be in this case?
>
> 3- For class TCP I will first state my understanding of the meaning of Be
in
> both rate-limit and MQC and explain why I used a Be of 4000. I'd like to
know
> if we will have an agreement about this explanation.
>
> -(Based on the "Policing with CAR" in the "policing and shaping overview"
In
> the config guide) Be in CAR is the biggest burst that would not be
considered
> as exceeding the rate limit. If we approximate CAR behaviour into a Token
> bucket (leaving out tehe effect of compound debt), this would be
analoguous to
> the sum of the first and second buckets full sizes. If Be is equal to Bc
in
> this syntax, the biggest burst is the conform burst, i.e no exceed bucket.
> Specifying a Be smaller than Bc would be meaningless with CAR.
>
> - (Based on the command reference for the police command) In MQC the be is
the
> full size of the second bucket only. This means that specifying 0 means no
> second bucket. A be equal to or even smaller than bc would be possible
with
> this syntax.
>
> This is why I specified be=4000 and not 8000. This comes from (be in
> rate-limit - bc in rate-limit)
>
> 4- I understand the solution in the workbook approximates CAR behavour to
a
> single token bucket mechanism in MQC with a size of 4000 (the specified Be
of
> 8000 is redundant since no violate-action). The purpose may be to
approximate
> the compound debt behaviour to applying the exceed-action to all traffic
> exceeding the single bucket. In my opinion this is too severe.
>
> It might have been more appropriate to approximate the behaviour to a
single
> bucket of size 8000. I have chosen to use a dual-bucket with sizes 4000
and
> 4000 and apply the exceed-action of the CAR to the violate-action.
>
> I'd like to have the group's opinions on this subject. How would you have
done
> it? If one of the Brians would be also kind enough to comment ..
>
> Regards,
> Sameh
>
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