Re: CIR in FRTS

While I think you have a point about looking at the access rate, there
is another key to remember in the scenario presented.

As people who configure this daily and implement it per the SP's
guidelines, we would tend to think of DE marking as indicating traffic
not under contract, HOWEVER there is a key phrase in this scenario
which lends itself to determining that the CIR is 128k and that minCIR
is 48k:

" *during congestion* your provider will mark any traffic in excess of
48 kbps as discard eligible."

Generally speaking, traffic outside of CIR is marked DE. If the
scenario is stating that it is marked DE only during periods of
congestion, then it seems to be that CIR would be the 128k even though
we would probably never ever purchase it in this manner (that is, a
rate that is committed and not DE until congestion occurs)

The difference is that if we call it excess traffic, we are saying
that the traffic is truly out of contract. Furthermore, the scenario
limits the use of variables to cir, mincir, and Tc (translates into
Bc, blahblah)

Under normal conditions, we want to be able to send 128K. Under normal
conditions, this is fine. During congestion we will receive BECN and
turn on the adaptive shape. We are absolutely, positively, without a
doubt guaranteed 48kbps.

--William McCall

On Wed, Jul 15, 2009 at 7:27 AM, Santiago
Enciso<santiago.enciso_at_gmail.com> wrote:
> From my point of view this should be the confiruration
>
> 128 Kbps = Access rate (physical limit of the interface)
> 48 Kbps = CIR
> 48 Kbps = MINCIR
> Bc = 6.000 bps
> Be = 10.000 bps (AR - CIR)/tc
> Tc = 125 msec
> frame-relay adaptive-shaping becn
>
> The requirements allow to burst above the CIR (until 128kbps) but if
> congestion is notified by the service provider with BECN bit set the
> interface should send again at mincir wich in this case is the CIR.
>
> HTH
>
> Santiago E
>
>
> -----Mensaje original-----
> De: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] En nombre de andrew
> Enviado el: Miircoles, 15 de Julio de 2009 07:17
> Para: 'Vinu'; 'kaniyath minha'
> CC: 'Cisco certification'
> Asunto: RE: CIR in FRTS
>
> You mincir could just as easily be 48k given that the service provider has
> given you a CIR of 48K, you will always have that amount of bandwidth, if
> adaptive shaping is on you transmission rate can be dropped to mincir not
> cir.
>
> So I would use mincir because in an adaptive shaping scenario if you used
> CIR you could end up only transmitting at 24k a sec
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Vinu
> Sent: Wednesday, July 15, 2009 7:20 PM
> To: kaniyath minha
> Cc: Cisco certification
> Subject: Re: CIR in FRTS
>
> Hi Minha,
>
> If your contract with SP states "during congestion your provider will mark
> any traffic in excess of 48 kbps as discard eligible ", your CIR is 48Kbps
> and your Peak information rate would be 128kbps. and Tc is 125 ms
>
> On Wed, Jul 15, 2009 at 12:52 PM, kaniyath minha
> <minha.kaniyath_at_gmail.com>wrote:
>
>> Dear
>>
>> I have one doubt in following question.
>>
>> Question
>>
>> Configure the R3 frame relay interface for rate limiting by configuring
> the
>> parameters CIR,
>> TC and MINCIR,
>>
>> considering the following :
>>
>> Your maximum throughput is 128 kbps, during congestion your provider will
>> mark any
>> traffic in excess of 48 kbps as discard eligible. Make sure your
> throughput
>> changes
>> accordingly, based upon BECN received only, your token bucket interval in
>> 125 ms.
>>
>>
>> In this question What is CIR 128 or 48?
>>
>> Please help me.
>>
>> Thanks and Regards
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
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>>
>>
>>
>>
>>
>>
>>
>
>
> --
> Regards,
>
> Vinu
> CCIE# 16439
>
>
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>
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>
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>
> _______________________________________________________________________
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>
>
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>
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Received on Wed Jul 15 2009 - 08:05:06 ART