From: Chris Lewis (chrlewiscsco@gmail.com)
Date: Fri Mar 03 2006 - 11:54:20 GMT-3
Just to clarify what I was saying regarding default Tc being set by the
speed of the link.
With no Bc specified in a frame-relay map class and a cir of 128000, the
router will pick a Tc of 125 msec.
With no Bc specified in a frame-relay map class and a cir of 1024000, the
router will pick a Tc of 63 msec.
The following config and show output illustrate this behavior.
map-class frame-relay test
frame-relay cir 1024000
!
interface Serial0/0
ip address 172.16.123.1 255.255.255.0
encapsulation frame-relay
no fair-queue
frame-relay class test
frame-relay traffic-shaping
frame-relay map ip 172.16.123.2 122 broadcast
Relevant output of the show frame pvc 122 command
cir 1024000 bc 1024000 be 0 byte limit 8064 interval 63
You can of course manually over-ride this selection by explicitly setting
the Bc value.
Chris
On 3/1/06, Brian McGahan <bmcgahan@internetworkexpert.com> wrote:
>
> The Tc is set by configuring the Bc.
>
> Brian McGahan, CCIE #8593
> bmcgahan@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
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> ________________________________________
> From: Ahmed Shams [mailto:ahmedshamz@gmail.com]
> Sent: Wednesday, March 01, 2006 12:02 PM
> To: Brian McGahan
> Cc: PANDI MOORTHY; Cisco certification
> Subject: Re: Frame-relay Traffic Shapping Question
>
> Thank you for your input Brian. Is it true that you are not supposed to
> change the Tc value and tweak the Bc and CIR and let IOS determine the Tc
> for you?? I don't know where I read this but Cisco doesnt recommend you to
> do that..
>
> Please advice..
> On 3/1/06, Brian McGahan < bmcgahan@internetworkexpert.com> wrote:
> > If no Tc value is given, it defaults to 125 msec (1/8th of a second).
> For
> > MINCIR though, it defaults to half of the configured CIR.
>
> It actually depends on what the CIR is. The higher the CIR the
> lower the default Tc. Technically all you need to do is set the CIR
> value and the IOS will automatically choose the appropriate Tc. You
> really only need to set the Tc when the serialization delay for your
> traffic is an issue. So in other words if the question doesn't state
> what to put just don't put anything.
>
> HTH,
>
> Brian McGahan, CCIE #8593
> bmcgahan@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987 x 705
> Outside US: 775-826-4344 x 705
> 24/7 Support: http://forum.internetworkexpert.com
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>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto: nobody@groupstudy.com] On Behalf
> Of
> > Ahmed Shams
> > Sent: Tuesday, February 28, 2006 11:05 PM
> > To: PANDI MOORTHY
> > Cc: Cisco certification
> > Subject: Re: Frame-relay Traffic Shapping Question
> >
> > If no Tc value is given, it defaults to 125 msec (1/8th of a second).
> For
> > MINCIR though, it defaults to half of the configured CIR.
> > > For Voice over Frame though, you have to configure the parameters in
> such
> > a
> > way that they should reflect the Tc value of 10msec 10ms (1/100th of a
> > second).
> >
> > Enable traffic-shaping without specifying any parameters on your frame
> > interface and see what "show traffic-shape" gets you
> >
> > I would recommend you to go to InternetworkExpert.com and read through
> > their
> > white paper on FRTS. Also, their sample lab contains useful
> information on
> > the topic, which atleast I found very interesting easy to understand.
> >
> > HTH
> >
> > On 3/1/06, PANDI MOORTHY <moorthypandi@gmail.com> wrote:
> > >
> > > Hi Group
> > >
> > > Question on the Frame-relay traffic shaping.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > 1) The question is ask to configure provisioned rate on the FR
> > interface,
> > > but doesn't specify the TC, value, so in this case what would be the
> Tc
> > > value should I need to choose. (is it the minimum value 10)
> > >
> > >
> > >
> > >
> > >
> > > 2) I have the configuration as below.
> > >
> > >
> > >
> > > !
> > >
> > > map-class frame-relay DLCI_403
> > >
> > > frame-relay cir 1024000
> > >
> > > frame-relay bc 10240
> > >
> > >
> > >
> > >
> > >
> > > I have CIR 1024k and the BC value as well, I haven't specify the
> minicir
> > > value in this configuration. What would be the minicir value when
> there
> > is
> > > congestion in the network? (Is it the default value 56k?)
> > >
> > >
> > >
> > >
> > >
> > > Please give me your input on this, thanks in advance.
> > >
> > >
> > > Regards.
> > > Pandi
> > >
> > >
> _______________________________________________________________________
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> >
> >
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