From: Petr Lapukhov (petr@internetworkexpert.com)
Date: Fri Nov 17 2006 - 14:54:14 ART
Properly tuning the Bc/Be values for a policer, you may achieve drop
behavior
"close" to RED. Cisco usually recommend their classic values for Bc/Be,
but you may, for instance, consider the following paper:
http://www.cnaf.infn.it/~ferrari/tfngn/cat6500/police/tcp/
to get more detailed understanding of TCP behavior under policing.
2006/11/17, John Moor <johmoor@gmail.com>:
>
> On 11/17/06, John Moor <johmoor@gmail.com> wrote:
> >
> > Yes guys I know this consideration about TCP sessions drop and slow
> down.
> > The thing which does interest me the most is:
> >
> > 1) How much could this imact the network. How much benefit/speed
> anything
> > else we can get when using shaping instead of policing for outside
> traffic
> > on the outside interface of the customer network?? Are there some
> > applications which would very much depend on what is configured shaping
> or
> > policing?? Some examples...
> >
> >
> > P.S To SavJani: If we don't want dorp our own traffic we wouldn't
> > configured anything either policing or shaping correct??? From this I
> would
> > probably formulate following subquestion:
> >
> > What could be bad.... if we do not configure shaping at all on the
> outside
> > interface?? Say Provider have configured policing and we didn't
> configure
> > anything...
> >
> >
> > On 11/17/06, SAVJANI, HITESH, WWCS <hitesh@att.com> wrote:
> > >
> > > John,
> > >
> > > Here is the way I understand.
> > >
> > > 1 Shaping on the enterprise edge : Being a customer we would want to
> > > push as much data as we can without dropping anything. If we use
> > > policing we will be droping our own traffic which will not make any
> > > sense. Will it?
> > >
> > > 2 Policing on the Provider edge : Being a service provider, I wouldn't
> > > want to allow my customer to send anything more than he is paying for.
> > > So, I will drop anything above the limit. Another reason is sometimes
> > > being a provider I will sell my 100 Mb pipe as 200 Mb ;-). It does
> > > happen & is called oversubscribing. In this case I would definitely
> want
> > > my customer to stick to his allocated bandwidth.
> > >
> > > Shaping should be used when you don't want traffic to get dropped.
> > > Policing will drop all the traffic which is more than the value
> > > configured. I would not suggest to use policing on an interface going
> to
> > > the provider. However you may want to use policing inbound on that
> same
> > > interface. It's all based on what you want to accomplish.
> > >
> > > HTH,
> > >
> > > Hitesh Savjani
> > > CCIE # 17151
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > > John Moor
> > > Sent: Friday, November 17, 2006 9:51 AM
> > > To: Cisco certification
> > > Subject: shaping vs policing real life
> > >
> > > Hello guys,
> > >
> > > 1. We all know the difference between policing and shaping (how they
> > > drop
> > > the packets). Also usually in the real life policing is configured on
> > > the
> > > provider edge and shaping is configured on the customer edge.
> > >
> > > 2. Guys could you please explain me why do we use shaping on the
> > > enterprise
> > > edge and not policing. Could you please give me a couple of real life
> > > theoretical examples when it could be logically explained why using
> > > shaping
> > > is much better than using policing??
> > >
> > > Thanks,
> > >
> > >
> _______________________________________________________________________
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-- Petr Lapukhov, CCIE #16379 petr@internetworkexpert.comInternetwork Expert, Inc. http://www.InternetworkExpert.com Toll Free: 877-224-8987 Outside US: 775-826-4344
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