From: Vince Mashburn (cciegroupstudy@gmail.com)
Date: Wed May 23 2007 - 15:23:16 ART
The reason that shape peak is 512 is that it sends bc + be every interval.
By default, be is equal to bc, so you are transmitting 256 + 256 = 512.
On 5/21/07, Bit Gossip <bit.gossip@chello.nl> wrote:
>
> Group,
> I have done a quick test to confirm the behaviour of 'shape average' vs
> 'shape peak': below the figures and here the results:
> - with standard setting for Bc and Be -> 'shape average 256000' shapes
> @
> 256kbps while 'shape peak 256000' shapes @ 512kbps
> - with Be=0 -> shape peak = shape average
> Thanks,
> bit.
>
>
> Baseline:
> serial link with clockrate 2015232 and no shaping configured:
> R3#show int s4/3 | i second output rate
> 30 second output rate 864000 bits/sec, 198 packets/sec
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> shape average 256000
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> R3#show policy-map int s4/3
> Serial4/3
>
> Service-policy output: SHAPE
>
> Class-map: class-default (match-any)
> 9230 packets, 5046624 bytes
> 30 second offered rate 248000 bps, drop rate 0 bps
> Match: any
> Traffic Shaping
> Target/Average Byte Sustain Excess Interval Increment
> Rate Limit bits/int bits/int (ms) (bytes)
> 256000/256000 1984 7936 7936 31 992
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> shape peak 256000
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> R3#show policy-map int s4/3
> Serial4/3
>
> Service-policy output: SHAPE
>
> Class-map: class-default (match-any)
> 34492 packets, 18871214 bytes
> 30 second offered rate 456000 bps, drop rate 0 bps
> Match: any
> Traffic Shaping
> Target/Average Byte Sustain Excess Interval Increment
> Rate Limit bits/int bits/int (ms) (bytes)
> 512000/256000 1984 7936 7936 31 1984
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> shape peak 256000 7936 0
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> R3#show policy-map int s4/3
> Serial4/3
>
> Service-policy output: SHAPE
>
> Class-map: class-default (match-any)
> 64692 packets, 35386586 bytes
> 30 second offered rate 244000 bps, drop rate 0 bps
> Match: any
> Traffic Shaping
> Target/Average Byte Sustain Excess Interval Increment
> Rate Limit bits/int bits/int (ms) (bytes)
> 256000/256000 992 7936 0 31 992
>
>
> ----- Original Message -----
> From: "maureen schaar" <maureen.schaar@gmail.com>
> To: "Hewie" <whewetson@gmail.com>
> Cc: "Mike O" <mikeeo@email.msn.com>; "Skinner, Stephen"
> <Stephen.Skinner@rbs.co.uk>; <ccielab@groupstudy.com>
> Sent: Monday, April 16, 2007 11:51 AM
> Subject: Re: shape average vs shape peak
>
>
> >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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