Contents

Overhead Accounting

Overhead accounting enables the router to account for packet overhead when shaping traffic to a specific rate. This accounting ensures that the router executes quality of service (QoS) features on the actual bandwidth used by subscriber traffic.


Note

Overhead Accounting is not the same as Traffic Shaping Overhead Accounting for ATM, documented here: http://www.cisco.com/en/US/docs/ios/12_2sb/feature/guide/ovrhactg.html

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Restrictions for Overhead Accounting

  • Overhead Accounting values are in bytes.

  • You can set one Overhead Accounting value per policy.

  • Overhead Accounting is supported only for the shape and bandwidth commands.

  • Overhead Accountingis supported only on LAN and WAN interfaces.

  • You can enable overhead accounting for shaping and bandwidth on top-level parent policies, middle-level child policies, and bottom-level child policies.

  • When you enter the show policy-map interface command, the resulting classification byte counts and the queuing feature byte counts do not match. This mismatch occurs because the classification byte count does not consider overhead, whereas the queuing features do consider overhead.

Information About Overhead Accounting

Overhead Accounting factors in packet datagram sizes. The following features use packet datagram size to make decisions in data plane operation; they use Overhead Accounting:

  • Rate-limited priority queue (conditional policer)

  • WRED (random drop)

  • Qlimit (tail drop)

  • Shaping

  • Bandwidth operations

How to Use Overhead Accounting

Overhead Accounting is disabled by default. You set the Overhead Accounting value. Configuring Overhead Accounting on a queue does not change queueing parameters you have already configured.

Enabling Overhead Accounting

SUMMARY STEPS

    1.    enable

    2.    configure {terminal | memory | network}

    3.    policy-map policy-name

    4.    class{class-name | class-default}

    5.    bandwidth{bandwidth-kbps |percentpercentage|remaining percentpercentage}[account{subscriber-encap} | {user-definedoffset}]

    6.    exit

    7.    policy-map policy-name

    8.    class{class-name | class-default}

    9.    shape[average|peak]mean-rate [burst-size] [excess-burst-size]account{subscriber-encapsulation |user-definedoffset}

    10.    service-policypolicy-map-name

    11.    exit


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Router> enable
     

    Enables higher privilege levels, such as privileged EXEC mode.

    Enter your password if prompted.

     
    Step 2 configure {terminal | memory | network}


    Example:
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 3 policy-map policy-name


    Example:
    Router(config)# policy-map policy1
     

    Specifies the name of the policy map created earlier.

    Enter policy map name.

     
    Step 4class{class-name | class-default}

    Example:
    Router(config-pmap)# class class1
     

    Enters policy-map configuration mode.

     
    Step 5bandwidth{bandwidth-kbps |percentpercentage|remaining percentpercentage}[account{subscriber-encap} | {user-definedoffset}]

    Example:
    Router(config-pmap-c)# bandwidth percent 20
     

    Enables class-based fair queuing and overhead accounting.

     
    Step 6 exit


    Example:
    Router(config-pmap-c)# exit
     

    Exits the policy-map class configuration mode.

     
    Step 7 policy-map policy-name


    Example:
    Router(config)# policy-map policy1
     

    Specifies the name of the policy map created earlier.

    Enter policy map name.

     
    Step 8class{class-name | class-default}

    Example:
    Router(config-pmap)# class class1
     

    Enters policy-map configuration mode.

     
    Step 9shape[average|peak]mean-rate [burst-size] [excess-burst-size]account{subscriber-encapsulation |user-definedoffset}

    Example:
    Router(config-pmap-c)# shape average 1000000 account user-defined 33
     

    Shapes traffic to the indicated bit rate according to the algorithm specified or to enable overhead accounting.

     
    Step 10service-policypolicy-map-name


    Example:
    Router(config-pmap-c)# service-policy oh-child-bw
     

    Applies a child policy to the parent class-default class. Do not specify the input or output keywords when applying a child policy to a parent class-default class.

     
    Step 11 exit


    Example:
    Router(config-pmap-c)# exit
     

    Exits the policy-map class configuration mode.

     

    Verifying Overhead Accounting

    SUMMARY STEPS

      1.    enable

      • Enter your password if prompted.

      2.    show policy-map [policy-map-name]

      • (Optional) Enter the policy map name. The name can be a maximum of 40 alphanumeric characters.

      3.    show policy-map interface

      4.    show running-config

      5.    exit


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable
      • Enter your password if prompted.


      Example:
      Router> enable
       

      Enables higher privilege levels, such as privileged EXEC mode.

       
      Step 2show policy-map [policy-map-name]
      • (Optional) Enter the policy map name. The name can be a maximum of 40 alphanumeric characters.


      Example:
      Router# show policy-map unit-test
       

      (Optional) Displays the configuration of all classes for a specified policy map or of all classes for all existing policy maps.

       
      Step 3show policy-map interface


      Example:
      Router# show policy-map serial2/0
       

      (Optional) Displays the statistics and the configurations of the input and output policies that are attached to an interface.

       
      Step 4show running-config


      Example:
      Router# show running-config
       

      (Optional) Displays the contents of the currently running configuration file.

       
      Step 5 exit


      Example:
      Router(config-pmap-c)# exit
       

      Exits the policy-map class configuration mode.

       

      Configuration Examples for Overhead Accounting

      This example shows a two-level policy with Overhead Accounting on the parent shaper and a child that has bandwidth configured: 

      policy-map oh-child-bw
class oh-child
bandwidth percent 20

policy-map oh1
class class-default
shape average 1000000 account user-defined 33
service-policy oh-child-bw

      Additional References

      Related Documents

      Related Topic

      Document Title

      Cisco IOS commands

      Cisco IOS Master Commands List, All Releases

      Standards and RFCs

      Standard/RFC

      Title

      MIBs

      MIB

      MIBs Link

      To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

      http:/​/​www.cisco.com/​go/​mibs

      Technical Assistance

      Description

      Link

      The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

      http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

      Feature Information for Overhead Accounting

      Feature Name Releases Feature Information
      Overhead Accounting 15.2(1)T

      Overhead accounting enables the router to account for packet overhead when shaping traffic to a specific rate. This accounting ensures that the router executes quality of service (QoS) features on the actual bandwidth used by subscriber traffic.

      The following commands were introduced or modified: shape and bandwidth.

      Overhead Accounting

      Overhead Accounting

      Overhead accounting enables the router to account for packet overhead when shaping traffic to a specific rate. This accounting ensures that the router executes quality of service (QoS) features on the actual bandwidth used by subscriber traffic.


      Note

      Overhead Accounting is not the same as Traffic Shaping Overhead Accounting for ATM, documented here: http://www.cisco.com/en/US/docs/ios/12_2sb/feature/guide/ovrhactg.html

      Finding Feature Information

      Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

      Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

      Restrictions for Overhead Accounting

      • Overhead Accounting values are in bytes.

      • You can set one Overhead Accounting value per policy.

      • Overhead Accounting is supported only for the shape and bandwidth commands.

      • Overhead Accountingis supported only on LAN and WAN interfaces.

      • You can enable overhead accounting for shaping and bandwidth on top-level parent policies, middle-level child policies, and bottom-level child policies.

      • When you enter the show policy-map interface command, the resulting classification byte counts and the queuing feature byte counts do not match. This mismatch occurs because the classification byte count does not consider overhead, whereas the queuing features do consider overhead.

      Information About Overhead Accounting

      Overhead Accounting factors in packet datagram sizes. The following features use packet datagram size to make decisions in data plane operation; they use Overhead Accounting:

      • Rate-limited priority queue (conditional policer)

      • WRED (random drop)

      • Qlimit (tail drop)

      • Shaping

      • Bandwidth operations

      How to Use Overhead Accounting

      Overhead Accounting is disabled by default. You set the Overhead Accounting value. Configuring Overhead Accounting on a queue does not change queueing parameters you have already configured.

      Enabling Overhead Accounting

      SUMMARY STEPS

        1.    enable

        2.    configure {terminal | memory | network}

        3.    policy-map policy-name

        4.    class{class-name | class-default}

        5.    bandwidth{bandwidth-kbps |percentpercentage|remaining percentpercentage}[account{subscriber-encap} | {user-definedoffset}]

        6.    exit

        7.    policy-map policy-name

        8.    class{class-name | class-default}

        9.    shape[average|peak]mean-rate [burst-size] [excess-burst-size]account{subscriber-encapsulation |user-definedoffset}

        10.    service-policypolicy-map-name

        11.    exit


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example:
        Router> enable
         

        Enables higher privilege levels, such as privileged EXEC mode.

        Enter your password if prompted.

         
        Step 2 configure {terminal | memory | network}


        Example:
        Router# configure terminal
         

        Enters global configuration mode.

         
        Step 3 policy-map policy-name


        Example:
        Router(config)# policy-map policy1
         

        Specifies the name of the policy map created earlier.

        Enter policy map name.

         
        Step 4class{class-name | class-default}

        Example:
        Router(config-pmap)# class class1
         

        Enters policy-map configuration mode.

         
        Step 5bandwidth{bandwidth-kbps |percentpercentage|remaining percentpercentage}[account{subscriber-encap} | {user-definedoffset}]

        Example:
        Router(config-pmap-c)# bandwidth percent 20
         

        Enables class-based fair queuing and overhead accounting.

         
        Step 6 exit


        Example:
        Router(config-pmap-c)# exit
         

        Exits the policy-map class configuration mode.

         
        Step 7 policy-map policy-name


        Example:
        Router(config)# policy-map policy1
         

        Specifies the name of the policy map created earlier.

        Enter policy map name.

         
        Step 8class{class-name | class-default}

        Example:
        Router(config-pmap)# class class1
         

        Enters policy-map configuration mode.

         
        Step 9shape[average|peak]mean-rate [burst-size] [excess-burst-size]account{subscriber-encapsulation |user-definedoffset}

        Example:
        Router(config-pmap-c)# shape average 1000000 account user-defined 33
         

        Shapes traffic to the indicated bit rate according to the algorithm specified or to enable overhead accounting.

         
        Step 10service-policypolicy-map-name


        Example:
        Router(config-pmap-c)# service-policy oh-child-bw
         

        Applies a child policy to the parent class-default class. Do not specify the input or output keywords when applying a child policy to a parent class-default class.

         
        Step 11 exit


        Example:
        Router(config-pmap-c)# exit
         

        Exits the policy-map class configuration mode.

         

        Verifying Overhead Accounting

        SUMMARY STEPS

          1.    enable

          • Enter your password if prompted.

          2.    show policy-map [policy-map-name]

          • (Optional) Enter the policy map name. The name can be a maximum of 40 alphanumeric characters.

          3.    show policy-map interface

          4.    show running-config

          5.    exit


        DETAILED STEPS
           Command or ActionPurpose
          Step 1 enable
          • Enter your password if prompted.


          Example:
          Router> enable
           

          Enables higher privilege levels, such as privileged EXEC mode.

           
          Step 2show policy-map [policy-map-name]
          • (Optional) Enter the policy map name. The name can be a maximum of 40 alphanumeric characters.


          Example:
          Router# show policy-map unit-test
           

          (Optional) Displays the configuration of all classes for a specified policy map or of all classes for all existing policy maps.

           
          Step 3show policy-map interface


          Example:
          Router# show policy-map serial2/0
           

          (Optional) Displays the statistics and the configurations of the input and output policies that are attached to an interface.

           
          Step 4show running-config


          Example:
          Router# show running-config
           

          (Optional) Displays the contents of the currently running configuration file.

           
          Step 5 exit


          Example:
          Router(config-pmap-c)# exit
           

          Exits the policy-map class configuration mode.

           

          Configuration Examples for Overhead Accounting

          This example shows a two-level policy with Overhead Accounting on the parent shaper and a child that has bandwidth configured: 

          policy-map oh-child-bw
class oh-child
bandwidth percent 20

policy-map oh1
class class-default
shape average 1000000 account user-defined 33
service-policy oh-child-bw

          Additional References

          Related Documents

          Related Topic

          Document Title

          Cisco IOS commands

          Cisco IOS Master Commands List, All Releases

          Standards and RFCs

          Standard/RFC

          Title

          MIBs

          MIB

          MIBs Link

          To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

          http:/​/​www.cisco.com/​go/​mibs

          Technical Assistance

          Description

          Link

          The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

          http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

          Feature Information for Overhead Accounting

          Feature Name Releases Feature Information
          Overhead Accounting 15.2(1)T

          Overhead accounting enables the router to account for packet overhead when shaping traffic to a specific rate. This accounting ensures that the router executes quality of service (QoS) features on the actual bandwidth used by subscriber traffic.

          The following commands were introduced or modified: shape and bandwidth.