Re: hierarchical shaping versus shaping in conjunction to cbwfq

From: Pierre-Alex (paguanel@hotmail.com)
Date: Sat Jun 03 2006 - 18:23:07 ART

Small mistake, 25 percent goest to each of the three customer and the rest to
the default-class.
  ----- Original Message -----
  From: Pierre-Alex
  To: Petr Lapukhov ; Chris Lewis
  Sent: Saturday, June 03, 2006 11:21 PM
  Subject: Re: hierarchical shaping versus shaping in conjunction to cbwfq

  Petr,

  Just for info, I found an example on cco of using both the "shape" and
"bandwidth" to the same value. :)

  Is my interpretation of this configurations correct:

  "The shapper creates a congestion points for the sub-classes at 241K. 241 K
of bandwidth is allocated to the shapping queue, out of which ,
  25 percent goes to each of the four customers."

  It does make sense to have the same value for the shapping and the queue in
this example doesn't it?

  =================================

  Policy Map GTS_in_ModCLI Configuration

  Router(config)# policy-map GTS_in_ModCLI

  Router(config-pmap)# class shaped

  Router(config-pmap-c)# bandwidth 241

  Router(config-pmap-c)# shape average 241000

  Router(config-pmap-c)# service-policy CBWFQ_in_GTS

  Policy Map CBWFQ_in_GTS Configuration

  The policy map called CBWFQ_in_GTS has four CBWFQ classes:

  Router(config)# policy-map CBWFQ_in_GTS

  Router(config-pmap)# class cust_A

  Router(config-pmap-c)# bandwidth percent 25

  Router(config-pmap)# class cust_B

  Router(config-pmap-c)# bandwidth percent 25

  Router(config-pmap)# class cust_C

  Router(config-pmap-c)# bandwidth percent 25

  Router(config-pmap)# class class-default

  Router(config-pmap-c)# fair

  In this second example, the Class-Based Shaping feature is configured for
the class called shaped in the policy map called GTS_in_ModCLI. The class
shaped is shaped to an average rate of 241,000 bits per second (bps). CBWFQ is
also enabled on the class, which guarantees a bandwidth of 241 kbps during
times of congestion at the interface.

  The shaped class is a congestion point for all the subclasses that comprise
that class. Therefore, the subclasses can be further differentiated in the
shaped class. All these subclasses are part of the policy map, CBWFQ_in_GTS,
that is attached to the shaped class.

  http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fqo
s_c/fqcprt4/qcfcbshp.htm#wp1002823
    ----- Original Message -----

    From: Petr Lapukhov
    To: Pierre-Alex
    Cc: ccielab@groupstudy.com
    Sent: Saturday, June 03, 2006 7:29 PM
    Subject: Re: hierarchical shaping versus shaping in conjunction to cbwfq

    Pierre,

    I may put the things a bit unclear, sorry :) The main thing I want
    to point at, is that "bandwith" and "shape" do quite different things.

    You are correct, one may use "bandwith" to allocate resourses in case
    of "oversubscription". It's just useless if you set "shape" and
"bandwidth"
    to equal values :)

    Say, if we have 512K physical port speed, and we need to divide it equally
    between two classes of traffic in case of congestion.

    To achieve that, we issue "bandwidth 256" under each class.

    But next, we want let every class use more of available bandwith, in case
    if it's actually available, but not too much :)

    So we shape every class to 384k:

    policy-map policy
    class class1
      shape average 384000
      bandwidth 256
    class class2
      shape average 384000
      bandwidth 256

    HTH
    Petr

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