From: Curt Girardin (curt.girardin@chicos.com)
Date: Fri Mar 03 2006 - 12:37:31 GMT-3
Team,
On a related subject:
On page 479 of Tim Szigeti's book "end-to-end QoS Network Design....",
it mentions "Because the FRTS mechanism does not take Frame Relay
overhead (headers and CRCs) into account in its calculations, it is
recommeded that the CIR be set slightly below the contracted speed of
the PVC." He goes on to suggest setting the CIR to 95% of the
contracted rate..
Does Tim Szigeti's suggestion above apply also to generic traffic
shaping, and class-based shaping?
Thanks,
Curt
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Chris Lewis
Sent: Friday, March 03, 2006 9:54 AM
To: Brian McGahan
Cc: Ahmed Shams; PANDI MOORTHY; Cisco certification
Subject: Re: Frame-relay Traffic Shapping Question
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
> Toll Free: 877-224-8987 x 705
> Outside US: 775-826-4344 x 705
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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
> Live Chat: http://www.internetworkexpert.com/chat/
>
> > -----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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