From: Chris Lewis (chrlewiscsco@gmail.com)
Date: Thu Jun 29 2006 - 19:04:43 ART
I have done some more tests and had an off-line discussion with Brian,
With one router I got the results where shape peak 64000 and shape average
64000 returened the same CIR, this was my first test.
A second test on a different router showed that shape peak 64000 8000 8000
gave a CIR of 128K, which is what Petr was saying originally. Brian obtained
similar test results.
I have asked internal development what the right answer should be going
forward and I may or may not get an answer I can post :)
In any case I would say it is extremely unlikely that the R&S exam will pose
a question requiring shape peak. It would have to use very weird wording
which I for one have not seen in the exam.
Chris
On 6/29/06, Brian McGahan <bmcgahan@internetworkexpert.com> wrote:
>
> The difference between them is how Be is accumulated. With
> shape average the algorithm uses a system of credit, where Be is only
> accumulated if you haven't sent enough Bc. With shape peak the
> algorithm uses a system of debit, where Be is sent right off the bat,
> and then paid back at a later time. The difference between them is the
> delay that the traffic will see inside of the second, but overall you
> will still never exceed CIR over a longer term average.
>
>
> 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
> > Chris Lewis
> > Sent: Thursday, June 29, 2006 12:55 PM
> > To: Petr Lapukhov
> > Cc: Elias Chari; Anderson Mota Alves; ccielab@groupstudy.com
> > Subject: Re: Doubt in QoS
> >
> > Hi Petr,
> >
> > What I described in my first response holds for both shape average and
> > shape
> > peak. Unles I am misunderstanding what you wrote, it is not an
> accurate
> > description of the operation of shape peak. It is possible to veryify
> this
> > with a simple test. Consider the topology below:
> >
> > R3----ethernet----R1-----128K serial line----R2
> >
> > Then do an extended ping with low timeout and large packet sizes from
> R3
> > to
> > R2. If you crets a service policy like the test 1 and 2 below, and
> apply
> > it
> > outbound on R1 towards R3 (with access-list 1 matching all packets),
> set
> > the
> > load interval to 30 on that interface as well, you will then see that
> both
> > shape average and shape peak will after a few minutes indicate an
> output
> > rate of 62000 bits per second. The disparity with the configured
> shaped
> > rate
> > is due to the way one will measure layer 3 bandwidth only.
> >
> > Test 1
> >
> > class-map match-all TEST
> > match access-group 1
> > !
> > !
> > policy-map TEST
> > class TEST
> > shape average 64000 8000 8000
> >
> > Test 2
> >
> > class-map match-all TEST
> > match access-group 1
> > !
> > !
> > policy-map TEST
> > class TEST
> > shape peak 64000 8000 8000
> >
> > The net effect is as I described, the difference between shape peak
> and
> > shape average only exists if there is credit to be used by the shaper,
> > hence
> > the CIR achieved by both is the same.
> >
> > Chris
> >
> >
> > On 6/29/06, Petr Lapukhov <petr@internetworkexpert.com> wrote:
> > >
> > > Correct, Chris.
> > >
> > > But AFAIK that rule does not work with "shape peak".
> > > It always send up Bc+Be every Tc, effectively ending
> > > with CIR*(1+Bc/Be) rate.
> > >
> > > --
> > >
> > > Petr Lapukhov, CCIE #16379
> > > petr@internetworkexpert.com
> > >
> > > Internetwork Expert, Inc.
> > > http://www.InternetworkExpert.com
> <http://www.internetworkexpert.com/>
> > > Toll Free: 877-224-8987
> > > Outside US: 775-826-4344
> > >
> > > 2006/6/29, Chris Lewis <chrlewiscsco@gmail.com>:
> > > >
> > > > Just a note of caution here. The shaper can only utilize the Be
> tokens
> > > if
> > > credit has been built up, meaning that the shaper has been
> transmitting
> > at
> > > below CIR for a period of time. Be does not allow you to constantly
> > > transmit
> > > at a rate above CIR, it is only available if traffic has dropped
> below
> > > CIR.
> > > Over time, you should still acerage out at CIR.
> > >
> > > Chris
> > >
> > >
> > > On 6/29/06, Elias Chari < elias.chari@gmail.com> wrote:
> > > >
> > > > Andy,
> > > >
> > > > It is when you configure shape peak 96000 (not average) that you
> get
> > > upto
> > > > 192k.
> > > >
> > > > If not specified bc and be default to the same value, then peak =
> > 2*CIR
> > > as
> > > > per the formula. Also if only cir and bc are specified the bc
> value is
> > > > used
> > > > for be
> > > >
> > > > Rack1R1#sh policy-map int s0/1
> > > > Serial0/1
> > > >
> > > > Service-policy output: testB
> > > >
> > > > Class-map: testB (match-all)
> > > > 0 packets, 0 bytes
> > > > 5 minute offered rate 0 bps, drop rate 0 bps
> > > > Match: any
> > > > Queueing
> > > > Output Queue: Conversation 265
> > > > Bandwidth 84 (kbps) Max Threshold 64 (packets)
> > > > (pkts matched/bytes matched) 0/0
> > > > (depth/total drops/no-buffer drops) 0/0/0
> > > > Traffic Shaping
> > > > Target/Average Byte Sustain
> > > Excess Interval Increment
> > > > Rate Limit bits/int bits/int (ms)
> > (bytes)
> > > > *192000/96000 1992 7968 7968 83
> 1992*
> > > >
> > > > Adapt Queue Packets Bytes Packets Bytes
> > Shaping
> > > > Active Depth Delayed Delayed
> Active
> > > > - 0 0 0 0 0 no
> > > >
> > > > Class-map: class-default (match-any)
> > > > 0 packets, 0 bytes
> > > > 5 minute offered rate 0 bps, drop rate 0 bps
> > > > Match: any
> > > > On 6/29/06, Anderson Mota Alves < mota_anderson@hotmail.com>
> wrote:
> > > > >
> > > > > Hi Petr,
> > > > >
> > > > > Based on your explanation below it's more clear to me that you
> > cannot
> > > > mix
> > > > > "priority" and "shape" because one is for policing and the other
> for
> > > > > shaping purposes.
> > > > >
> > > > > But I've been seaching in cisco webpage and from the link below
> it
> > > says:
> > > > >
> > > > > You can specify two types of traffic shaping; average rate
> shaping
> > and
> > > > > peak rate shaping. Average rate shaping limits the transmission
> rate
> > > to
> > > > > the CIR. Using the CIR ensures that the average amount of
> traffic
> > > being
> > > > > sent conforms to the rate expected by the network.
> > > > >
> > > > > Peak rate shaping configures the router to send more traffic
> than
> > the
> > > > > CIR. To determine the peak rate, the router uses the following
> > > formula:
> > > > >
> > > > > peak rate = CIR(1 + Be / Bc)
> > > > >
> > > > >
> > > >
> > >
> >
> http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_
> re
> > ference_chapter09186a0080087f34.html#wp1077189
> > > > >
> > > > >
> > > > > But how do I know that configuring the "shape average 96000" I
> can
> > > send
> > > > > traffic up to 192 kbps?
> > > > >
> > > > > Thanks,
> > > > >
> > > > > Andy
> > > > >
> > > > >
> --------------------------------------------------------------------
> > > > >
> > > > > From: "Petr Lapukhov" < petr@internetworkexpert.com>
> > > > > To: "Anderson Mota Alves" <mota_anderson@hotmail.com >,
> > > > > < ccielab@groupstudy.com>
> > > > > Subject: Re: Doubt in QoS
> > > > > Date: Thu, 29 Jun 2006 14:42:55 +0400
> > > > > >The first one seems to be "almost" correct:
> > > > > >
> > > > > >You shape (limit) traffic up to 96kbit here - the only problem
> > > > > >is "peak" keyword. This configuration actually permits you to
> send
> > > > > >traffic up to 192kbit by default. So I would better do
> something
> > > > > >like:
> > > > > >
> > > > > >...
> > > > > >class CRITICAL
> > > > > > shape average 96000
> > > > > > bandwidth 84
> > > > > >...
> > > > > >
> > > > > >This way you guarantee 84k in case of congestion,
> > > > > >and limit flow up to 96k in any case.
> > > > > >
> > > > > >As for your second example - you can not mix priority and
> > bandwidth:
> > > > > >
> > > > > >R6(config-pmap-c)#priority 64
> > > > > >R6(config-pmap-c)#bandwidth 92
> > > > > >Must remove priority configuration from this class first.
> > > > > >
> > > > > >Also remember that you cannot mix "priority" and "shape",
> > > > > >and dont forget that "priority" actually police your traffic
> in
> > > > > >case of congestion.
> > > > > >
> > > > > >Finally, you may choose "police" instead of "shape", with
> > > > > >your first example. The decision should depend on task wording.
> > > > > >
> > > > > >HTH
> > > > > >---
> > > > > >Petr Lapukhov, CCIE #16379
> > > > > > petr@internetworkexpert.com
> > > > > >
> > > > > >Internetwork Expert, Inc.
> > > > >
> >
> >http://www.InternetworkExpert.com
> tt
> > p://www.internetworkexpert.com/
> > > >
> > > > > >Toll Free: 877-224-8987
> > > > > >Outside US: 775-826-4344
> > > > > >
> > > > > >----- Original Message ----- From: "Anderson Mota Alves"
> > > > > ><mota_anderson@hotmail.com>
> > > > > >To: <ccielab@groupstudy.com>
> > > > > >Sent: Thursday, June 29, 2006 2:16 PM
> > > > > >Subject: Doubt in QoS
> > > > > >
> > > > > >
> > > > > >>Hi gurus, The question I need to complish is the following:
> > > > > >>
> > > > > >>Which configuration provides the mission-critical traffic
> class
> > > > > >>with a
> > > > > >>minimum
> > > > > >>
> > > > > >>bandwidth guarantee of 84 kbps and a maximum upper bandwidth
> limit
> > > > > >>of 96
> > > > > >>
> > > > > >>kbps?
> > > > > >>
> > > > > >>I think I have to solution for this one but I'm not sure if
> I'm
> > > > > >>right:
> > > > > >>
> > > > > >>policy-map shape
> > > > > >>class mission-critical
> > > > > >>bandwidth 84
> > > > > >>shape peak 96000
> > > > > >>
> > > > > >>or
> > > > > >>
> > > > > >>policy-map shape
> > > > > >>class mission-critical
> > > > > >>priority 64
> > > > > >>bandwidth 96
> > > > > >>
> > > > > >>Could anyone tell me which one I could use? Also I don't know
> if
> > in
> > > > > >>order
> > > > > >>to use the shape peak I need to first configure the shape cir
> ir
> > > > > >>order to
> > > > > >>make sure that this will be the peak above the Cir.
> > > > > >>
> > > > > >>Thanks
> > > > > >>
> > > > >
> > > >
> > >
> >
> >>______________________________________________________________________
> _
> > > > > >>Subscription information may be found at:
> > > > > >>http://www.groupstudy.com/list/CCIELab.html
> > > > >
> > > > >
> > >
> _______________________________________________________________________
> > > > > Subscription information may be found at:
> > > > > http://www.groupstudy.com/list/CCIELab.html
> > > >
> > > >
> >
> _______________________________________________________________________
> > > > Subscription information may be found at:
> > > > http://www.groupstudy.com/list/CCIELab.html
> > >
> > >
> _______________________________________________________________________
> > >
> > > Subscription information may be found at:
> > > http://www.groupstudy.com/list/CCIELab.html
> >
> >
> _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Sat Jul 01 2006 - 07:57:34 ART