Configuring IP SLA - Percentile Support for Filtering Outliers

This module describes how to configure the percentile option for IP SLAs to examine a set of network measurements that are within a specified percentile of the return packets. This feature improves Cisco IP Service Level Agreements (SLAs) by providing the capability to measure round-trip times within a percentile, such as the 95th percentile of RTT, in order to examine a set of measurements that are 95% faster and 5% slower.

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Information About IP SLA - Percentile Support for Filtering Outliers

Percentile Measurements

The IP SLA- Percentile Support for Filtering Outliers feature enables IP SLAs to calculate min/average/max values for all packets, excluding those with the highest x% measured value. For example, if you have a ten-packet probe with nine 1-ms RTT values and one 50-ms RTT value, the percentile will exclude the outlier (50-ms) and report a min/avg/max value of 1/1/1, not 1/5/50.

IP SLAs reactions are configured to trigger when a monitored value exceeds or falls below a specified level. If IP SLAs measures too high or too low for any configured reaction, IP SLAs can generate a notification to a network management application or trigger another IP SLA operation to gather more data. The percentile reactions work the same way except that the monitored value is the percentile min/max/average. A count is keep of all the packets that violate the threshold value and at the end of the operation, that value is subtracted from the total packets received, then divided by the total, and a success ratio is generated. This value is referenced by a new reaction type that generates a notification when a percentage ratio is not met. For information, see the ip sla reaction-configuration command in the IP SLAs Command Reference.

How to Configure IP SLA - Percentile Support for Filtering Outliers

Configuring the IP SLAs Responder on a Destination Device


Note

A responder should not configure a permanent port for a sender. If the responder configures a permanent port for a sender, even if the packets are successfully sent (no timeout or packet-loss issues), the jitter value is zero.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    Enter one of the following commands:

    • ip sla responder
    • ip sla responder udp-echo ipaddress ip-address port portvrf vrf

    4.    end


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example:
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3Enter one of the following commands:
    • ip sla responder
    • ip sla responder udp-echo ipaddress ip-address port portvrf vrf


    Example:
    Device(config)# ip sla responder
    Device(config)# ip sla responder udp-echo ipaddress 192.0.2.132 port 5000 vrf vrf1
     

    (Optional) Temporarily enables IP SLAs responder functionality on a Cisco device in response to control messages from the source.

    (Optional; required only if protocol control is disabled on the source.) Enables IP SLAs responder functionality on the specified IP address, port and VRF.

    • Protocol control is enabled by default.

     
    Step 4 end


    Example:
    Device(config)# end
     

    Exits global configuration mode and returns to privileged EXEC mode.

     

    Configuring an IP SLAs Operation Using the Percentile Option

    Before You Begin

    • The IP SLAs operation to be configured for percentile support must be configured on the source device. For configuration information, see the appropriate module in the IP SLAs Configuration Guide. The percentile option can be configured for the following IP SLAs operations:

      • Ethernet jitter—See the “Manually Configuring an IP SLAs Ethernet Ping or Jitter Operation on the Source Device” section of the “Configuring IP SLAs for Metro-Ethernet” module.

      • ICMP jitter—See the “Configuring Cisco IP SLAs ICMP Operations” module.

      • UDP jitter—See the “IP SLAs UDP Jitter Operations” module.

    • For a UDP jitter operation, an IP SLAs responder must be configured on the destination device. For configuration information, see the “Configuring an IP SLAs Responder on the Destination Device” section.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    ip sla operation-number

      4.    percentile {jitteravg | jitterds | jittersd | owds | owsd | rtt} percent

      5.    end


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example: 
      Device> enable
       
      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2configure terminal


      Example: 
      Device# configure terminal
       

      Enters global configuration mode.

       
      Step 3ip sla operation-number


      Example: 
      Device(config)# ip sla 10
       

      Begins configuration for an IP SLAs operation and enters IP SLA configuration mode.

      Note   

      For the purpose of this configuration task, the operation to be configured for percentile support is a preconfigured ICMP jitter operation.

       
      Step 4percentile {jitteravg | jitterds | jittersd | owds | owsd | rtt} percent


      Example: 
      Device(config-ip-sla-jitter)# percentile jitteravg 95
       

      Configures the percentile option for an IP SLAs operation.

       
      Step 5end


      Example: 
      Device(config-ip-sla-jitter)# end
       

      Returns to privileged EXEC mode.

       

      Scheduling IP SLAs Operations

      Before You Begin

      • All IP Service Level Agreements (SLAs) operations to be scheduled must be already configured.
      • The frequency of all operations scheduled in a multioperation group must be the same.
      • The list of one or more operation ID numbers to be added to a multioperation group must be limited to a maximum of 125 characters in length, including commas (,).

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    Enter one of the following commands:

        • ip sla schedule operation-number [life {forever | seconds}] [start-time {[hh:mm:ss] [month day | day month] | pending | now | after hh:mm:ss}] [ageout seconds] [recurring]
        • ip sla group schedule group-operation-number operation-id-numbers {schedule-period schedule-period-range | schedule-together} [ageout seconds] frequency group-operation-frequency [life {forever | seconds}] [start-time {hh:mm [:ss] [month day | day month] | pending | now | after hh:mm [:ss]}]

        4.    end

        5.    show ip sla group schedule

        6.    show ip sla configuration


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example: 
        Device> enable
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.

         
        Step 2 configure terminal


        Example: 
        Device# configure terminal
         

        Enters global configuration mode.

         
        Step 3 Enter one of the following commands:
        • ip sla schedule operation-number [life {forever | seconds}] [start-time {[hh:mm:ss] [month day | day month] | pending | now | after hh:mm:ss}] [ageout seconds] [recurring]
        • ip sla group schedule group-operation-number operation-id-numbers {schedule-period schedule-period-range | schedule-together} [ageout seconds] frequency group-operation-frequency [life {forever | seconds}] [start-time {hh:mm [:ss] [month day | day month] | pending | now | after hh:mm [:ss]}]


        Example: 
        Device(config)# ip sla schedule 10 life forever start-time now
        Device(config)# ip sla group schedule 10 schedule-period frequency
        Device(config)# ip sla group schedule 1 3,4,6-9 life forever start-time now 
        Device(config)# ip sla schedule 1 3,4,6-9 schedule-period 50 frequency range 80-100
         

        • Configures the scheduling parameters for an individual IP SLAs operation.

        • Specifies an IP SLAs operation group number and the range of operation numbers for a multioperation scheduler.

         
        Step 4 end


        Example: 
        Device(config)# end
         

        Exits global configuration mode and returns to privileged EXEC mode.

         
        Step 5 show ip sla group schedule


        Example: 
        Device# show ip sla group schedule
         

        (Optional) Displays IP SLAs group schedule details.

         
        Step 6 show ip sla configuration


        Example: 
        Device# show ip sla configuration
         

        (Optional) Displays IP SLAs configuration details.

         

        Troubleshooting Tips

        • If the IP Service Level Agreements (SLAs) operation is not running and not generating statistics, add the verify-data command to the configuration (while configuring in IP SLA configuration mode) to enable data verification. When data verification is enabled, each operation response is checked for corruption. Use the verify-data command with caution during normal operations because it generates unnecessary overhead.

        • Use the debug ip sla trace and debug ip sla error commands to help troubleshoot issues with an IP SLAs operation.

        What to Do Next

        To add proactive threshold conditions and reactive triggering for generating traps (or for starting another operation) to an IP Service Level Agreements (SLAs) operation, see the “Configuring Proactive Threshold Monitoring” section.

        Verifying IP SLAs Operations

        Perform this task to display and interpret the results of an IP SLAs operation. Check the output for fields that correspond to the criteria in your service level agreement to determine whether the service metrics are acceptable.

        SUMMARY STEPS

          1.    enable

          2.    show ip sla statistics


        DETAILED STEPS
          Step 1   enable

          Enables privileged EXEC mode.

          • Enter your password if prompted.


          Example: 
          Device> enable

          Step 2   show ip sla statistics

          Displays and interprets the results of an IP SLAs operation.



          Example: 

          Device> show ip sla statistics

          Configuration Examples for IP SLA - Percentile Support for Filtering Outliers

          Example: Configuring IP SLA - Percentile Support for Filtering Outliers

          The following example shows how to configure an IP SLAs ICMP jitter operation with the percentile option: 

          ip sla 1 
	icmp-jitter 192.168.0.129 interval 40 num-packets 100 source-ip 10.1.2.34 
	percentile jitteravg 95 
! 
ip sla reaction-configuration 1 react jitterAvgpct threshold-value 5 2 action-type trap threshold-type immediate 
! 
ip sla schedule 1 start-time now life forever

          Additional References for IP SLA - Percentile Support for Filtering Outliers

          Related Documents

          Related Topic Document Title

          Cisco IOS commands

          Cisco IOS Master Command List, All Releases

          Cisco IOS IP SLAs commands

          IP SLAs Command Reference

          Cisco IP SLAs configuration tasks

          IP SLAs Configuration Guide

          Standards and RFCs

          Standard/RFC Title

          • CISCO-RTTMON-MIB

          • CISCO-RTTMON-ICMP-MIB

          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

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          http:/​/​www.cisco.com/​support

          Feature Information for IP SLA - Percentile Support for Filtering Outliers

          The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

          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.
          Table 1 Feature Information for IP SLA - Percentile Support for Filtering Outliers

          Feature Name

          Releases

          Feature Information

          IP SLA - Percentile Support for Filtering Outliers

          Cisco IOS 15.3(2)T

          This feature improves Cisco IP Service Level Agreements (SLAs) by providing the capability to measure round-trip times within a percentile, such as the 95th percentile of RTT, in order to examine a set of measurements that are 95% faster and 5% slower.

          The following commands were introduced or modified: ip sla reaction-configuration, percentile, show ip sla statistics