From: Vince Mashburn (cciegroupstudy@gmail.com)
Date: Mon Apr 16 2007 - 12:18:30 ART
Shape average will also send bc and be, so you can have extended burst with
that as well. The main difference is that shape peak sends bc + be EVERY
INTERVAL and shape average delays the sending of the be by an interval (if
there is enough bandwidth available). So, I think that would answer the
question of why you are actually seeing 512 + 512 = 1024 k sent every
interval using shape peak.
On 4/16/07, maureen schaar <maureen.schaar@gmail.com> wrote:
>
> I would like to add something that may not be obvious from the doccd
> (and I had to research myself to fully understand). When using shape
> average, there can be bursting above the cir for 1 Tc, but only after
> accumulating credit. Credit (or tokens) are accumulated by sending
> below the cir. The next Tc, the the left-over tokens from the previous
> Tc can be used for bursting upto the Be. So this means bursting for a
> very very short period, whereas shape peak allows bursting for long
> periods (as long as bandwidth is available).
>
> As far as Hewie's answer to ' obtain a throughput up to a peak of 512
> kbps', I would not use shape peak 256000, but shape peak 512000. The
> target rate in this case is 512000 (the average rate = cir = 256000).
> As long as bandwidth is available, 512000 will be sent, so this is the
> throughput (indeed it is 2xCIR when using the defaults).
>
> HTH
>
> Maureen
>
> On 4/15/07, Hewie <whewetson@gmail.com> wrote:
> > Hi,
> >
> > Some more from Cisco
> >
> > The Be allows more than the Bc to be sent during a time interval under
> > certain conditions. Therefore, DTS provides two types of shape commands:
> *
> > average* and *peak*. When shape average is configured, the interface
> sends
> > no more than the Bc for each interval, achieving an average rate no
> higher
> > than the CIR. When shape peak is configured, *the interface sends Bc
> plus Be
> > bits in each interval*
> >
> > So according to the formula peak rate = CIR(1+Be/Bc) and the output of
> 'show
> > policy-map interface' the peak rate 'could' be CIR x 2, therefore I
> think
> > the COD is incorrect by using 'shape peak 512000' to obtain a throughput
> *up
> > to* a peak of 512 kbps, it should be 'shape peak 256000' to obtain a
> > throughput up to a peak of 512 kbps
> >
> > Will be good to hear some more comments :-)
> >
> > Hewie
> >
> >
> > On 4/15/07, Mike O <mikeeo@email.msn.com> wrote:
> > >
> > > Here is an output from the router. If you do shape peak 512000 you
> > > actually
> > > are allowing 1024000 bps. If you do shape peak 256000 that actually
> gives
> > > you a peak output of 512k.
> > >
> > > Scott, Brad or the Brians can you chime in?
> > >
> > >
> > >
> > >
> > >
> > > policy-map PEAK
> > > class SHAPE
> > > bandwidth 300
> > > shape peak 512000
> > > !
> > > Router#sh policy-map interface s0/0
> > >
> > > Serial0/0
> > >
> > > Service-policy output: PEAK
> > >
> > > Class-map: SHAPE (match-any)
> > > 0 packets, 0 bytes
> > > 5 minute offered rate 0 bps, drop rate 0 bps
> > > Match: ip precedence 1
> > > 0 packets, 0 bytes
> > > 5 minute rate 0 bps
> > > Traffic Shaping
> > > Target/Average Byte Sustain
> Excess Interval Increment
> > > Rate
> Limit bits/int bits/int (ms) (bytes)
> > > 1024000/512000 3200 12800 12800 25 3200
> > >
> > > !
> > > !
> > > policy-map PEAK
> > > class SHAPE
> > > bandwidth 300
> > > shape peak 256000
> > >
> > > Router#sh policy-map interface s0/0
> > >
> > > Serial0/0
> > >
> > > Service-policy output: PEAK
> > >
> > > Class-map: SHAPE (match-any)
> > > 0 packets, 0 bytes
> > > 5 minute offered rate 0 bps, drop rate 0 bps
> > > Match: ip precedence 1
> > > 0 packets, 0 bytes
> > > 5 minute rate 0 bps
> > > Queueing
> > > Output Queue: Conversation 265
> > > Bandwidth 300 (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)
> > > 512000/256000 1984 7936 7936 31 1984
> > >
> > >
> > > ----- Original Message -----
> > > From: "Skinner, Stephen" <Stephen.Skinner@rbs.co.uk>
> > > To: <ccielab@groupstudy.com>
> > > Sent: Sunday, April 15, 2007 10:29 AM
> > > Subject: RE: shape average vs shape peak
> > >
> > >
> > > >I too would like to know the answer ,
> > > >
> > > > Taking another CCO example
> > > >
> > > > The following example uses peak rate shaping to ensure a bandwidth
> of
> > > 300
> > > > kbps but allow throughput up to 512 kbps if enough bandwidth is
> > > available
> > > > on
> > > > the interface:
> > > >
> > > > bandwidth 300
> > > > shape peak 512000
> > > >
> > > > This seems to set an arbitrary amount..
> > > >
> > > > But if as Cisco has stated ..
> > > >
> > > > 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)
> > > >
> > > > Then how did they come up with the figure above.
> > > >
> > > > Many thanks in advance
> > > >
> > > > Stephen Skinner
> > > >
> > > >
> > > > mail: Stephen.Skinner@rbs.co.uk
> > > >
> > > > -----Original Message-----
> > > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]
> > > > Sent: 15 April 2007 01:50
> > > > To: WorkerBee
> > > > Cc: Mike O; ccielab@groupstudy.com
> > > > Subject: Re: shape average vs shape peak
> > > >
> > > > *** WARNING : This message originates from the Internet ***
> > > >
> > > > Hi all,
> > > >
> > > > I cut out an example from the hyperlink that was referenced. Can
> anyone
> > > > explain why the solution uses *shape peak 512000* when peak rate =
> > > > CIR(1+Be/Bc)?
> > > >
> > > >
> > > > Thanks!
> > > >
> > > >
> > > > *CBWFQ in Conjunction with GTS Example *
> > > >
> > > > The following example uses CBWFQ at the interface and shapes the
> traffic
> > > > before it is queued to CBWFQ.
> > > >
> > > > In this example, two classes are definedcust1 and cust2. The class
> > > cust1
> > > > is
> > > > ensured a bandwidth of 256 kbps, and the output is shaped to 384
> kbps.
> > > The
> > > > class cust2 is ensured a bandwidth of 384 kbps, but if enough
> bandwidth
> > > is
> > > > available on the interface, the class can obtain throughput up to a
> peak
> > > > of
> > > > 512 kbps.
> > > >
> > > > Figure
> > > > 1<
> > >
> http://www.cisco.com/en/US/products/sw/iosswrel/ps1834/products_feature_gu
> > > > i
> > > > de09186a00800800fc.html#wp1025976>illustrates
> > > > this example.
> > > >
> > > > Figure 1 CBWFQ in Conjunction with GTS
> > > >
> > > > The following commands are used to configure this example:
> > > >
> > > > Router(config)# *policy-map shape-cbwfq*
> > > >
> > > > Router(config-pmap)# *class cust1*
> > > >
> > > > Router(config-pmap-c)# *shape average 384000*
> > > >
> > > > Router(config-pmap-c)# *bandwidth 256*
> > > >
> > > > Router(config-pmap)# *class cust2*
> > > >
> > > > Router(config-pmap-c)# *shape peak 512000*
> > > >
> > > > Router(config-pmap-c)# *bandwidth 384*
> > > >
> > > > Router(config-pmap-c)# *configure terminal*
> > > >
> > > > Router(config)# *interface Serial 3/3*
> > > >
> > > > Router(config-if)# *service out shape-cbwfq*
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > On 4/14/07, WorkerBee <ciscobee@gmail.com> wrote:
> > > >>
> > > >> Specifying Average Rate or Peak Rate Traffic Shaping Design Rule
> > > >> ================================================
> > > >>
> > > >> Traffic shaping limits the rate of transmission of data.
> > > >>
> > > >> You can specify two types of traffic shaping; average rate shaping
> and
> > > >> peak rate shaping. Average rate shaping limits the transmission
> rate
> > > >> to the committed information rate (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) >> peak = CIR + [Be/Tc] which is more
> than
> > > >> CIR.
> > > >>
> > > >> where:
> > > >>
> > > >> Be is the Excess Burst rate.
> > > >>
> > > >> Bc is the Committed Burst rate.
> > > >>
> > > >> Peak rate shaping allows the router to burst higher than average
> rate
> > > >> shaping. However, using peak rate shaping, the traffic sent above
> the
> > > >> CIR (the delta) has the potential of being dropped if the network
> > > >> becomes congested.
> > > >>
> > > >> If your network has additional bandwidth available (over the
> > > >> provisioned CIR) and the application or class can tolerate
> occasional
> > > >> packet loss, that extra bandwidth can be exploited through the use
> of
> > > >> peak rate shaping. However, there may be occasional packet drops
> when
> > > >> network congestion occurs. If the traffic being sent to the network
> > > >> must strictly conform to the configured network provisioned CIR,
> then
> > > >> you should use average traffic shaping.
> > > >>
> > > >> R6(config-pmap-c)#shape ?
> > > >>
> > > >> average configure token bucket: CIR (bps) [Bc (bits) [Be
> > > >> (bits)]],
> > > >> send out Bc only per interval
> > > >>
> > > >> peak configure token bucket: CIR (bps) [Bc (bits) [Be
> > > >> (bits)]],
> > > >> send out Bc+Be per interval
> > > >>
> > > >>
> > > >>
> > > >>
> > > >
> > >
> >
>
http://www.cisco.com/en/US/products/sw/iosswrel/ps1834/products_feature_guid
> > > > e
> > > > 09186a00800800fc.html#wp1019894
> > > >>
> > > >>
> > > >> On 4/14/07, Mike O <mikeeo@email.msn.com> wrote:
> > > >> > I'm a little confused on these. Does shape average just use Bc
> and
> > > >> > peak
> > > >> uses
> > > >> > Bc and Be? I'm trying to figure out why you would use one over
> the
> > > >> other?
> > > >> >
> > > >> >
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