From: Mike O (mikeeo@email.msn.com)
Date: Sun Apr 15 2007 - 11:59:38 ART
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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