Re: FRTS Lab 1 - 7.2 question.

From: Godswill Oletu (oletu@inbox.lv)
Date: Tue Jun 06 2006 - 09:23:02 ART

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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.
> >
> >
> >
> > Send instant messages to your online friends
http://uk.messenger.yahoo.com
> >
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