From: Leigh Harrison (ccileigh@gmail.com)
Date: Tue Jun 06 2006 - 09:59:37 ART
Godswill,
Good point well made. I glanced at the question and the numbers made
sense to me.
Andi,
Please take the other explanations as correct.
LH
Godswill Oletu wrote:
> LH,
>
> Maybe, you are talking about 'fragments' which are in bytes, otherwise,
> 'CIR' are in bits/second; 'Bc' in Bits and 'Be' in Bits.
>
> I think it has to do the value of the default 'Tc' (the Tc value used when
> none is supplied) which is 125ms.
>
> Be=(AR- CIR) * Tc/1000
> =(128000 * 125/1000
> =16000
>
> 1/4 Be = Be / 4 = 16000/ 4
> = 4000
>
> My only problem is that, the orignal posted mentioned 'Bc' instead of 'Be'.
> I do not see how 'Bc' will result in a Burst, except I am missing something
> here or in the question. 'Bc' simply tell us how much need to be transmitted
> per timing interval to conform to our 'CIR'; which is in our case every
> 125ms and to conform to our 'CIR' of 128K, that value is 16000. 'Be' tell us
> that, after fulfilling our allocated quota and we have room, how much above
> CIR should we Burst?
>
> Since, the Access Rate (AR) was not given in the task, it is safe to assume
> that 'AR' is equal to 'CIR', making both 'Bc' & 'Be' to be equal and 1/4 of
> Be will be 4000.
>
> Please, set me straight if I am missing something here.
>
> Thanks.
> Godswill Oletu
>
>
> ----- Original Message -----
> From: "Leigh Harrison" <ccileigh@gmail.com>
> To: "Andi Bennett" <bigandibennett@yahoo.com>
> Cc: <ccielab@groupstudy.com>
> Sent: Tuesday, June 06, 2006 6:39 AM
> Subject: Re: FRTS Lab 1 - 7.2 question.
>
>
>
>> Hey there Andi,
>>
>> CIR is in bits, Bc is in bytes
>>
>> 128,000 / 4 = 32,000 _bits_ per interval
>>
>> 32,000 / 8 = 4,000 _bytes_ per interval
>>
>> Hope that helps a bit,
>>
>> LH
>>
>> Andi Bennett wrote:
>>
>>> Dear group.
>>> Being a bit crap at FRTS can somebody explain the answer to the Lab 1
>>>
> 7.2 question.
>
>>> 128K CIR and allow for 1/4th for burst.
>>>
>>> How does this come up with bc = 4000 ?
>>>
>>> Am I missing something here?
>>> Cheers
>>> A.
>>>
>>>
>>>
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