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Flexible NetFlow Configuration Guide

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Book Title

Flexible NetFlow Configuration Guide

Chapter Title

Flexible NetFlow - Layer 2 Fields

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Updated:
September 15, 2017

Chapter: Flexible NetFlow - Layer 2 Fields

Flexible NetFlow - Layer 2 Fields

The Flexible NetFlow - Layer 2 Fields feature enables collecting statistics for Layer 2 fields such as MAC addresses and virtual LAN (VLAN) IDs from traffic.

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.

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.

Information About Flexible NetFlow Layer 2 Fields

Flexible NetFlow - Layer 2 Fields Overview

The Flexible NetFlow - Layer 2 Fields feature enables collecting statistics for Layer 2 fields such as MAC addresses and virtual LAN (VLAN) IDs from traffic.

How to Configure Flexible NetFlow Layer 2 Fields

Creating a Flow Record

Perform this task to configure a customized flow record.

Customized flow records are used to analyze traffic data for a specific purpose. A customized flow record must have at least one match criterion for use as the key field and typically has at least one collect criterion for use as a nonkey field.

There are hundreds of possible permutations of customized flow records. This task shows the steps that are used to create one of the possible permutations. Modify the steps in this task as appropriate to create a customized flow record for your requirements.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    flow record record-name

    4.    description description

    5.    match {ip | ipv6} {destination | source} address

    6.    Repeat Step 5 as required to configure additional key fields for the record.

    7.   

    8.    Repeat the above step as required to configure additional nonkey fields for the record.

    9.    end

    10.    show flow record record-name

    11.    show running-config flow record record-name


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 flow record record-name


    Example: 
    Device(config)# flow record FLOW-RECORD-1
     

    Creates a flow record and enters Flexible NetFlow flow record configuration mode.

    • This command also allows you to modify an existing flow record.

     
    Step 4 description description


    Example: 
    Device(config-flow-record)# description Used for basic traffic analysis
     

    (Optional) Creates a description for the flow record.

     
    Step 5 match {ip | ipv6} {destination | source} address


    Example: 
    Device(config-flow-record)# match ipv4 destination address
     
    Note   

    This example configures the IPv4 destination address as a key field for the record. For information about the other key fields available for the match ipv4 command, and the other match commands that are available to configure key fields.

     
    Step 6 Repeat Step 5 as required to configure additional key fields for the record.  

    —

     
    Step 7

    Example:
     

    Configures the input interface as a nonkey field for the record.

    Note   

    This example configures the input interface as a nonkey field for the record.

     
    Step 8 Repeat the above step as required to configure additional nonkey fields for the record.  

    —

     
    Step 9 end


    Example: 
    Device(config-flow-record)# end
     

    Exits Flexible NetFlow flow record configuration mode and returns to privileged EXEC mode.

     
    Step 10 show flow record record-name


    Example: 
    Device# show flow record FLOW_RECORD-1
     

    (Optional) Displays the current status of the specified flow record.

     
    Step 11 show running-config flow record record-name


    Example: 
    Device# show running-config flow record FLOW_RECORD-1
     

    (Optional) Displays the configuration of the specified flow record.

     

    Creating a Flow Monitor

    Perform this required task to create a customized flow monitor.

    Each flow monitor has a separate cache assigned to it. Each flow monitor requires a record to define the contents and layout of its cache entries. These record formats can be a user-defined format. An advanced user can create a customized format using the flow record command.

    Before You Begin

    If you want to use a customized record, you must create the customized record before you can perform this task. If you want to add a flow exporter to the flow monitor for data export, you must create the exporter before you can complete this task.


    Note

    You must use the no ip flow monitor command to remove a flow monitor from all of the interfaces to which you have applied it before you can modify the parameters for the record command on the flow monitor.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    flow monitor monitor-name

      4.    description description

      5.    record {record-name}

      6.    cache {timeout {active} seconds | { normal }

      7.    Repeat Step 6 as required to finish modifying the cache parameters for this flow monitor.

      8.    exporter exporter-name

      9.    end

      10.    show flow monitor [[name] monitor-name [cache [format {csv | record | table}]] ]

      11.    show running-config flow monitor monitor-name


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example: 
      > enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2 configure terminal


      Example: 
      # configure terminal
       

      Enters global configuration mode.

       
      Step 3 flow monitor monitor-name


      Example: 
      (config)# flow monitor FLOW-MONITOR-1
       

      Creates a flow monitor and enters Flexible NetFlow flow monitor configuration mode.

      • This command also allows you to modify an existing flow monitor.

       
      Step 4 description description


      Example: 
      (config-flow-monitor)# description Used for basic ipv4 traffic analysis
       

      (Optional) Creates a description for the flow monitor.

       
      Step 5 record {record-name}


      Example: 
      (config-flow-monitor)# record FLOW-RECORD-1
       

      Specifies the record for the flow monitor.

       
      Step 6 cache {timeout {active} seconds | { normal }


      Example:  
         
      Step 7 Repeat Step 6 as required to finish modifying the cache parameters for this flow monitor.  

      —

       
      Step 8 exporter exporter-name


      Example: 
      (config-flow-monitor)# exporter EXPORTER-1
       

      (Optional) Specifies the name of an exporter that was created previously.

       
      Step 9 end


      Example: 
      (config-flow-monitor)# end
       

      Exits Flexible NetFlow flow monitor configuration mode and returns to privileged EXEC mode.

       
      Step 10 show flow monitor [[name] monitor-name [cache [format {csv | record | table}]] ]


      Example: 
      # show flow monitor FLOW-MONITOR-2 cache
       

      (Optional) Displays the status for a Flexible NetFlow flow monitor.

       
      Step 11 show running-config flow monitor monitor-name


      Example: 
      # show running-config flow monitor FLOW_MONITOR-1
       

      (Optional) Displays the configuration of the specified flow monitor.

       

      Applying a Flow Monitor to an Interface

      Before it can be activated, a flow monitor must be applied to at least one interface. Perform this required task to activate a flow monitor.

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    interface type number

        4.    {ip | ipv6} flow monitor monitor-name {input | output}

        5.    Repeat Steps 3 and 4 to activate a flow monitor on any other interfaces in the device over which you want to monitor traffic.

        6.    end

        7.    show flow interface type number

        8.    show flow monitor name monitor-name cache format record


      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 interface type number


        Example:
        Device(config)# interface GigabitEthernet 0/0/0
         

        Specifies an interface and enters interface configuration mode.

         
        Step 4 {ip | ipv6} flow monitor monitor-name {input | output}

        Example:
        Device(config-if)# ip flow monitor FLOW-MONITOR-1 input
         

        Activates a flow monitor that was created previously by assigning it to the interface to analyze traffic.

         
        Step 5 Repeat Steps 3 and 4 to activate a flow monitor on any other interfaces in the device over which you want to monitor traffic.  

        —

         
        Step 6 end


        Example:
        Device(config-if)# end
         

        Exits interface configuration mode and returns to privileged EXEC mode.

         
        Step 7 show flow interface type number


        Example:
        Device# show flow interface GigabitEthernet 0/0/0
         

        Displays the status of Flexible NetFlow (enabled or disabled) on the specified interface.

         
        Step 8 show flow monitor name monitor-name cache format record


        Example:
        Device# show flow monitor name FLOW_MONITOR-1 cache format record
         

        Displays the status, statistics, and flow data in the cache for the specified flow monitor.

         

        Configuration Examples for Flexible NetFlow Layer 2 Fields

        Example: Configuring Flexible NetFlow for Monitoring MAC and VLAN Statistics

        The following example shows how to configure Flexible NetFlow for monitoring MAC and VLAN statistics.

        This example starts in global configuration mode. 

        !
 flow record LAYER-2-FIELDS-1
 match ipv4 source address
 match ipv4 destination address
 match datalink dot1q vlan output
 match datalink mac source address input
 match datalink mac source address output
 match datalink mac destination address input
 match flow direction
!
 exit
!
!
flow monitor FLOW-MONITOR-4
 record LAYER-2-FIELDS-1
 exit
!
ip cef
!
interface GigabitEthernet0/0/1
 ip address 172.16.6.2 255.255.255.0
 ip flow monitor FLOW-MONITOR-1 input
!

        Additional References

        Related Documents

        Related Topic

        Document Title

        Cisco IOS commands

        Cisco IOS Master Command List, All Releases

        Flexible NetFlow conceptual information and configuration tasks

        Flexible NetFlow Configuration Guide

        Flexible NetFlow commands

        Cisco IOS Flexible NetFlow Command Reference

        Standards/RFCs

        Standard

        Title

        No new or modified standards/RFCs are supported by this feature.

        —

        MIBs

        MIB

        MIBs Link

        None

        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 Flexible NetFlow - Layer 2 Fields

        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 Flexible NetFlow - Layer 2 Fields

        Feature Name

        Releases

        Feature Information

        Flexible NetFlow - Layer 2 Fields

        12.2(33)SRE

        12.4(22)T

        Cisco IOS XE Release 3.2SE

        Enables collecting statistics for Layer 2 fields such as MAC addresses and virtual LAN (VLAN) IDs from traffic.

        Support for this feature was added for Cisco 7200 and 7300 Network Processing Engine (NPE) series routers in Cisco IOS Release 12.2(33)SRE.

        The following commands were introduced or modified:

        collect datalink dot1q vlan, collect datalink mac, match datalink dot1q vlan, match datalink mac.

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