Re: QOS - RED

In the above Q, what wouldyou use as your MPD to meet the requirement :)

On Wed, Apr 1, 2009 at 12:19 AM, George Roman <georgeroman_at_gmail.com> wrote:

> Hi Ruhann,
>
> Here is how this works:
>
> -when you reach the lower limit (50 packets in your case) in the Q you
> start dropping packets than as bigger your queue gets you will be more
> aggressive on your drop (this drop is proportional to the value you set for
> the MPD).
> -When you reach higher limit (70 packets in your case) you will drop with
> the value you are set for the MPD. In your case if the value is 4 (this is
> the denominator) you will drop 1 out of 4 packets from the queue.
> After you exceed 70 packets you have taildrop.
>
> Best regards,
> George
>
>
>
>
> On Tue, Mar 31, 2009 at 10:42 PM, Ruhann <groupstudy_at_ru.co.za> wrote:
>
>> Hi peoples
>>
>> I would like to double check something I dont agree with.
>>
>> The question states as follow:
>> Congestion Avoidance:
>>
>> - Configure R6 to randomly drop packets before congestion occurs on the
>> Serial interface output queue.
>> - Ensure that traffic marked with critical precedence will not be
>> dropped
>> unless there are 50 packets in the output queue.
>> - If there are 70 critical packets in the output queue, R6 should
>> randomly drop 4 out of every 16 of these packets.
>> - In the case that there are more than 70 critical packets in the output
>> queue, they should all be dropped.
>> - Do not use any MQC commands to accomplish this task.
>>
>>
>> My solution to this was as follow:
>> interface Serial0/0
>> random-detect
>> random-detect precedence 5 50 70 4
>>
>> My question is about the MPD value to be worked out here.
>> How I understand this, to work out your MPD value you take 1/MPD to see
>> the
>> initial stage of RED,
>> in this example 4/16 = 1/4 , so the MPD=4
>> thus 1 in every 4 packets will be randomly dropped when RED kick in
>> (Q=51).
>>
>> As the Q depth increases so will the random drops, up until Q=70 where 4/4
>> will be dropped?
>>
>> Am I understanding this right, Cause the answer to this question was the
>> MPD
>> =8
>> ie : random-detect precedence 5 50 70 8
>>
>> Please share you though and point me right if im wrong. :)
>> --
>> <ruhann>
>>
>>
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>

-- 
<ruhann>
Blogs and organic groups at http://www.ccie.net