From: Scott Morris (swm@emanon.com)
Date: Fri Feb 20 2004 - 16:01:39 GMT-3
Mmmmm... Awful good question. Been something in the back of my mind
forever. It's referenced as such in Cisco's DCIINS course, but doesn't show
any further reading information.
I have seen the quote that you mention there below as well, but my
understanding of this was that the default operation if you enabled shaping
to BECN was that only 1 was listened to (hence the 1 or 1000 and the 25%
default). If you set mincir to something other than 25% of the CIR value,
it would listen to more than one.
Being that the default operation in general is to completely ignore BECN's,
it may really function either way.
Not sure.
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
JNCIS, et al.
IPExpert CCIE Program Manager
IPExpert Sr. Technical Instructor
swm@emanon.com/smorris@ipexpert.net
http://www.ipexpert.net
-----Original Message-----
From: Brian Dennis [mailto:bdennis@internetworkexpert.com]
Sent: Friday, February 20, 2004 12:28 PM
To: 'Scott Morris'; 'Ahmed Mustafa'; ccielab@groupstudy.com
Subject: RE: MINCIR
Scott,
Do you have any documentation that can verify your "That's for each BECN"
statement?
<Quote>
When a BECN is received (and the command to pay attention to them is used),
then the router will back off of its target transmission (CIR) by 25%.
That's for each BECN. So if a second BECN is received, it would back off to
50% of the original target.
</Quote>
The documentation I've read states that the maximum you can drop per
interval is 25% no matter how many BECNs are received during the given
interval. See below:
<Quote>
frame relay adaptive-shaping becn
Implies that the PVC adapts the rate of transmit in response to the BECNs
received. The behaviour is as below:
If the PVC receives any BECNs during the current time interval (it doesn't
matter if this is one or 1000) the transmit rate is decreased by 25 percent.
It continues to drop with each BECN (limit one drop per time interval) until
the traffic rate gets to the mincir (guaranteed rate) where it stops.
</Quote>
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Scott Morris
Sent: Friday, February 20, 2004 6:06 AM
To: 'Ahmed Mustafa'; ccielab@groupstudy.com
Subject: RE: MINCIR
There's always an 'it depends'... The concept of mincir has to do with your
responding to BECN's in frame relay. When a BECN is received (and the
command to pay attention to them is used), then the router will back off of
its target transmission (CIR) by 25%. That's for each BECN. So if a second
BECN is received, it would back off to 50% of the original target.
You set mincir simply to say "don't go below this, no matter what BECN
information you receive". So whether you feel it best to pay attention to 1
BECN or 2 BECNs, or even more, it's up to you. If your lab gives
requirements about this, whether expressed in the number of BECNs or be
specifying a number for mincir, you certainly pay attention to that part!
HTH,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
JNCIS, et al.
IPExpert CCIE Program Manager
IPExpert Sr. Technical Instructor
swm@emanon.com/smorris@ipexpert.net
http://www.ipexpert.net
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Ahmed Mustafa
Sent: Friday, February 20, 2004 3:16 AM
To: ccielab@groupstudy.com
Subject: Re: MINCIR
Thanks Alsontra,
I was just referring to Brian because of Solution guide conflict, but I do
agree with you now, and it makes sense. If the calculations were not given
then what be your calculation for MINCIR. Eventhough the Solution guide
states MINCIR is half of CIR, but I referred to Solie's book, and he
mentioned that MINCIR should be calculated at 75% of CIR.
Brian or anyone please shed some light on this.
Regards,
Ahmed
----- Original Message -----
From: <alsontra@hotmail.com>
To: "Ahmed Mustafa" <ahmed.mustafa@sbcglobal.net>
Sent: Friday, February 20, 2004 12:39 AM
Subject: Re: MINCIR
> Hi Ahmed,
>
> I know your speaking directly to the Brians, but since this is a group....
> I see two things.
>
> 1. The sample lab gave a T-1 rate of 1536 and you used 1544.
> 2. The sample lab gave the minCir, so they're was no need for default
> calculation.
>
> All of the calculations checked out for me.
>
> DLCI 504 -
>
> tc 50ms= (1000/20) given
> bc 25600=(512000/20)
> be 51200=(1536000 - 512000)/20
> MinCir 384000=given
>
> DLCI 503 -
>
> tc 50ms= (1000/20) given
> bc 6400=(128000/20)
> be 0=no burst
> MinCir 96000=given
>
>
>
> __________________My config for the
> example______________________________
>
>
>
> map-class frame-relay 512k
> frame-relay cir 512000
> frame-relay bc 25600
> frame-relay be 51200
> frame-relay mincir 384000
> frame-relay adaptive-shaping becn
> !
> map-class frame-relay 128k
> frame-relay cir 128000
> frame-relay bc 6400
> frame-relay be 0
> frame-relay mincir 96000
> frame-relay adaptive-shaping becn
>
>
>
> ----- Original Message -----
> From: "Ahmed Mustafa" <ahmed.mustafa@sbcglobal.net>
> To: <ccielab@groupstudy.com>
> Sent: Thursday, February 19, 2004 8:56 PM
> Subject: MINCIR
>
>
> > Brian,
> >
> > Can you please verify this for me? I followed the Solution Guide,
> > but I
> have a
> > mismatch parameters between the solution guide and my calculations.
> >
> > According to the formula
> >
> > BC = CIR x Tc/1000
> > BE = (AR - CIR) x TC/1000
> >
> > For DLCI 513, the Bc should be 6400 and Be should be zero.
> > They match exactly according to your solution guide.
> >
> > For DLCI 504, the Bc should be 5600, and Be according to my
calculations,
> >
> > Be = (1544000 - 512000) x 50/1000 = 51600, but the soultion guide
> > states 51200.
> >
> > 2) The formula says mincir is half of CIR
> >
> > FOR DLCI 504, it should be then 256000 For DLCI 513, it should be
> > then 64000,
> >
> > But in solution guide, it was calculated at 75% of CIR.
> >
> > Regards,
> >
> > Ahmed
> >
> > ____________________________________________________________________
> > ___ Please help support GroupStudy by purchasing your study
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