Shape peak - DOC CD example is WRONG ??

From: Huan Pham (pnhuan@yahoo.com)
Date: Sat Nov 22 2008 - 11:00:51 ARST

Hi,

I posted a similar question few months ago, and I got a very good answer from Narbik. I also believe his answer is right.

http://www.groupstudy.com/archives/ccielab/200806/msg01899.html

However, today, I came accross an example in DOC CD, which left me wondering, whether DOC CD example is wrong or not. I did come accross few wrong example in the Doc CD before, and I believe this one is another one.

Really need your opinion on this, to clear things up.
 
Here's the link to the DOC CD:
 
http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_s1.html#wp1014690

shape

To specify average or peak rate traffic shaping, use the shape command in class-map configuration mode. To remove traffic shaping, use the no form of this command.

shape {average | peak} cir [bc] [be]

=================================================================

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
 
=================================================================

In my opinion, this configuration will give a peak rate of 1024K, instead of 512K.

here's the config, and what the show policy interface output:

Rack1R1#
class-map match-all WWW
 match protocol http

policy-map SHAPE
 class WWW
  bandwidth 300
  shape peak 512000

interface Serial0/0
 service-policy output SHAPE

Rack1R1#sh policy-map interface
 Serial0/0
  Service-policy output: SHAPE
    Class-map: WWW (match-all)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: protocol http
      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)
          1024000/512000 3200 12800 12800 25 3200
        Adapt Queue Packets Bytes Packets Bytes Shaping
        Active Depth Delayed Delayed Active
        - 0 0 0 0 0 no
    Class-map: class-default (match-any)
      1 packets, 13 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: any
 

I think the solution should be, following. Any opinion please?

bandwidth 300
shape peak 300000 37500 26500
 
Rack1R1#show policy-map interface
 Serial0/0
  Service-policy output: SHAPE
    Class-map: WWW (match-all)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: protocol http
      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)
           512000/300000 8000 37500 26500 125 8000
        Adapt Queue Packets Bytes Packets Bytes Shaping
        Active Depth Delayed Delayed Active
        - 0 0 0 0 0 no
    Class-map: class-default (match-any)
      293 packets, 64409 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: any

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