Traffic shaping : Peak rate versus shape average

From: wim.depauw@getronics.com
Date: Tue Jan 22 2008 - 18:03:57 ARST


Hi,

In Question 7.1 of IE workbook ( lab 9) they ask to configure an average rate of 5Mbps and a peak rate of 7.5Mbps . In the solution they work with the command shape average command + be and bc bits .
First I used the shape average and this worked fine .Then I started looking for an alternative:

I used the shape peak command ,

I started with shape peak 7500000 but then my target came to 9375000 and my average rate to 7500000 .

so I used my average rate in the policy map :

shape peak 5000000 160000 80000

It seems that my speed value in the shape peak command needs to be the average speed and not the peak rate.( see output below ) => Does anybody know why ? Although it stands differently in the command reference...

What is the difference between target rate and average rate ?

Rack1R4(config-pmap-c)#do sho policy-map int s1/0

 Serial1/0

  Service-policy output: lab9

    Class-map: class-default (match-any)
      122 packets, 2308 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: any
      Traffic Shaping
           Target/Average Byte Sustain Excess Interval Increment
             Rate Limit bits/int bits/int (ms) (bytes)
          7500000/5000000 30000 160000 80000 32 30000

        Adapt Queue Packets Bytes Packets Bytes Shaping
        Active Depth Delayed Delayed Active
        - 0 0 0 0 0 no
Rack1R4(config-pmap-c)#

Configuration

policy-map lab9
 class class-default
  shape peak 5000000 160000 80000

gr
wim



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