Consolidated Platform Configuration Guide, Cisco IOS XE 3.3SE (Catalyst 3850 Switches)
Configuring Flexible NetFlow
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Contents

Configuring Flexible NetFlow

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.

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

Prerequisites for Flexible NetFlow

The following are prerequisites for your Flexible NetFlow configuration:

  • You must configure a source interface. If you do not configure a source interface, the exporter will remain in a disabled state.
  • You must configure a valid record name for every flow monitor.

Prerequisites for Wireless Flexible NetFlow

The following are the prerequisites for wireless Flexible NetFlow:

  • Ensure that the networking device is running a Cisco release that supports wireless Flexible NetFlow.
  • Ensure that the target is connected to a WLAN.
  • The networking device must be configured to support protocol types such as IP, IPv6, and datalink.
  • Valid flow record and monitor are required before generating the flow.

Restrictions for Flexible NetFlow

The following are restrictions for Flexible NetFlow:

  • Traditional NetFlow (TNF) accounting is not supported.
  • Flexible NetFlow v5 export format is not supported, only NetFlow v9 export format is supported.
  • Both ingress and egress NetFlow accounting is supported.
  • Microflow policing feature shares the NetFlow hardware resource with FNF.
  • Only one flow monitor per interface and per direction is supported.
  • Layer 2, IPv4, and IPv6 traffic types are supported; however, the switch can apply a flow monitor to only one of these types at a time for a given direction and interface.
  • Layer 2, VLAN, WLAN and Layer 3 interfaces are supported, but the switch does not support SVI and tunnels.
  • The following NetFlow table sizes are supported:

    Trim Level

    Ingress NetFlow Table

    Egress NetFlow Table

    LAN Base

    Not supported

    Not supported

    IP Base

    8 K

    16 K

    IP Services

    8 K

    16 K

  • Depending on the switch type, a switch will have one or two forwarding ASICs. The capacities listed in the above table are on a per-ASIC basis.
  • The switch can support either one or two ASICs. Each ASIC has 8K ingress and 16 K egress entries.
  • The NetFlow tables are on separate compartments and cannot be combined. Depending on which ASIC processed the packet, the flows will be created in the table in the corresponding ASIC.
  • Both full flow accounting and sampled NetFlow accounting are supported.
  • NetFlow hardware implementation supports four hardware samplers. You can select a sampler rate from 1 out of 2 to 1 out of 1024. Only random sampling mode is supported.
  • With the microflow policing feature (which is enabled only for wireless implementation), NetFlow can and should be used only in full flow mode i.e. NetFlow policing cannot be used. For wireless traffic, applying a sampler is not permitted, as it hinders microflow QoS.
  • Only full flow accounting is supported for wireless traffic.
  • NetFlow hardware uses hash tables internally. Hash collisions can occur in the hardware. Therefore, in spite of the internal overflow Content Addressable Memory (CAM), the actual NetFlow table utilization could be about 80 percent.
  • Depending on what fields are used for the flow, a single flow could take two consecutive entries. IPv6 flows also take two entries. In these situations, the effective usage of NetFlow entries is half the table size, which is separate from the above hash collision limitation.
  • The switch supports up to 16 flow monitors.
  • Microflow policing uses a separate set of flow monitors (limit 3).
  • SSID-based NetFlow accounting is supported. SSID is treated in a manner similar to an interface. However, certain fields are not supported (such as AP MAC address and user ID ).
  • NetFlow v9 format NetFlow export is supported.
  • The NetFlow software implementation supports distributed NetFlow export, so the flows are exported from the same switch in which the flow was created.
  • Ingress flows are present in the ASIC that first received the packets for the flow. Egress flows are present in the ASIC from which the packets actually left the switch set up.
  • The reported value for the bytes count field (called “bytes long”) is Layer-2-packet-size—18 bytes. For classic Ethernet traffic (802.3), this will be accurate. For all other Ethernet types, this field will not be accurate. Use the "bytes layer2” field, which always reports the accurate Layer 2 packet size. For information about supported Flexible NetFlow fields, see Supported Flexible NetFlow Fields.

Information About NetFlow

NetFlow is a Cisco technology that provides statistics on packets flowing through the switch. NetFlow is the standard for acquiring IP operational data from IP networks. NetFlow provides data to enable network and security monitoring, network planning, traffic analysis, and IP accounting. Flexible NetFlow improves on original NetFlow by adding the capability to customize the traffic analysis parameters for your specific requirements. Flexible NetFlow facilitates the creation of more complex configurations for traffic analysis and data export through the use of reusable configuration components.

Flexible NetFlow Overview

Flexible NetFlow uses flows to provide statistics for accounting, network monitoring, and network planning.

A flow is a unidirectional stream of packets that arrives on a source interface and has the same values for the keys. A key is an identified value for a field within the packet. You create a flow using a flow record to define the unique keys for your flow.

The switch supports the Flexible NetFlow feature that enables enhanced network anomalies and security detection. Flexible NetFlow allows you to define an optimal flow record for a particular application by selecting the keys from a large collection of predefined fields.

All key values must match for the packet to count in a given flow. A flow might gather other fields of interest, depending on the export record version that you configure. Flows are stored in the Flexible NetFlow cache.

You can export the data that Flexible NetFlow gathers for your flow by using an exporter and export this data to a remote Flexible NetFlow collector.

You define the size of the data that you want to collect for a flow using a monitor. The monitor combines the flow record and exporter with the Flexible NetFlow cache information.

Wireless Flexible NetFlow Overview

The wireless Flexible NetFlow infrastructure supports the following:

  • Flexible NetFlow Version 9.0
  • User-based rate limiting
  • Microflow policing
  • Voice and video flow monitoring
  • Reflexive access control list (ACL)

Microflow Policing and User-Based Rate Limiting

Microflow policing associates a 2-color 1-rate policer and related drop statistics to each flow present in the NetFlow table. When the flow mask comprises all packet fields, this functionality is known as microflow policing. When the flow mask comprises either source or destination only, this functionality is known as user-based rate limiting.

Voice and Video Flow Monitoring

Voice and video flows are full flow mask-based entries. The ASIC provides the flexibility to program the policer parameters, share policers across multiple flows and rewrite the IP address and Layer 4 port numbers of these flows.


Note


For dynamic entries, the NetFlow engine will use the policer parameters that are derived for the flow based on the policy (ACL/QoS-based policies). Dynamic entries cannot share policer across multiple flows.


Reflexive ACL

Reflexive ACLs allow IP packets to be filtered based on upper-layer session information. The ACLs allow outbound traffic and limit inbound traffic in response to the sessions that originate inside the trusted network. The reflexive ACLs are transparent to the filtering mechanism until a data packet that matches the reflexive entry activates it. At this time, a temporary ACL entry is created and added to the IP-named access lists. The information obtained from the data packet to generate the reflexive ACL entry is permit/deny bit, the source IP address and port, the destination IP address, port, and the protocol type. During reflexive ACL entry evaluation, if the protocol type is either TCP or UDP, then the port information must match exactly. For other protocols, there is no port information to match. After this ACL is installed, the firewall is then opened for the reply packets to pass through. At this time, a potential hacker could have access to the network behind the firewall. To narrow this window, an idle timeout period can be defined. However, in the case of TCP, if two FIN bits or an RST is detected, the ACL entry can be removed.

Flow Records

A flow record defines the keys that Flexible NetFlow uses to identify packets in the flow, as well as other fields of interest that Flexible NetFlow gathers for the flow. You can define a flow record with any combination of keys and fields of interest. The switch supports a rich set of keys. A flow record also defines the types of counters gathered per flow. You can configure 64-bit packet or byte counters. The switch enables the following match fields as the defaults when you create a flow record:

  • match datalink—Layer 2 attributes
  • match flow—Flow identifying attributes
  • match interface—Interface attributes
  • match ipv4—IPv4 attributes
  • match ipv6—IPv6 attributes
  • match transport—Transport layer fields
Related Tasks

Flexible NetFlow Match Parameters

The following table describes Flexible NetFlow match parameters. You must configure at least one of the following match parameters for the flow records.

Table 1 Match Parameters

Command

Purpose

match datalink {dot1q | ethertype | mac | vlan }

Specifies a match to datalink or Layer 2 fields. The following command options are available:

  • dot1q—Matches to the dot1q field.
  • ethertype—Matches to the ethertype of the packet.
  • mac—Matches the source or destination MAC fields.
  • vlan—Matches to the VLAN that the packet is located on (input or output).

match flow direction

Specifies a match to the flow identifying fields.

match interface {input | output}

Specifies a match to the interface fields. The following command options are available:

  • input—Matches to the input interface.
  • output—Matches to the output interface.

match ipv4 {destination | protocol | source | tos | ttl | version}

Specifies a match to the IPv4 fields. The following command options are available:

  • destination—Matches to the IPv4 destination address-based fields.
  • protocol—Matches to the IPv4 protocols.
  • source—Matches to the IPv4 source address based fields.
  • tos—Matches to the IPv4 Type of Service fields.
  • ttl—Matches to the IPv4 Time To Live fields.
  • version—Matches to the IP version from the IPv4 header.

match ipv6 {destination | hop-limit | protocol | source | traffic-class | version }

Specifies a match to the IPv6 fields. The following command options are available:

  • destination—Matches to the IPv6 destination address-based fields.
  • hop-limit—Matches to the IPv6 hop limit fields.
  • protocol—Matches to the IPv6 payload protocol fields.
  • source—Matches to the IPv6 source address based fields.
  • traffic-class—Matches to the IPv6 traffic class.
  • version—Matches to the IP version from the IPv6 header.

match transport {destination-port | igmp | icmp | source-port}

Specifies a match to the Transport Layer fields. The following command options are available:

  • destination-port—Matches to the transport destination port.
  • icmp—Matches to ICMP fields, including ICMP IPv4 and IPv6 fields.
  • igmp—Matches to IGMP fields.
  • source-port—Matches to the transport source port.

Flexible NetFlow Collect Parameters

The following table describes the Flexible NetFlow collect parameters.

Table 2 Collect Parameters

Command

Purpose

collect counter { bytes { layer2 { long } | long } | packets { long } }

Collects the counter fields total bytes and total packets.

collect interface {input | output}

Collects the fields from the input or output interface.

collect timestamp absolute {first | last}

Collects the fields for the absolute time the first packet was seen or the absolute time the most recent packet was last seen (in milliseconds).

collect transport tcp flags

Collects the following transport TCP flags:
  • ack—TCP acknowledgement flag
  • cwr—TCP congestion window reduced flag
  • ece—TCP ECN echo flag
  • fin—TCP finish flag
  • psh—TCP push flag
  • rst—TCP reset flag
  • syn—TCP synchronize flag
  • urg—TCP urgent flag
Note   

On the switch, you cannot specify which TCP flag to collect. You can only specify to collect transport TCP flags. All TCP flags will be collected with this command.

Exporters

An exporter contains network layer and transport layer details for the Flexible NetFlow export packet. The following table lists the configuration options for an exporter.

Table 3  Flexible NetFlow Exporter Configuration Options

Exporter Configuration

Description

default

Sets a command to its default values.

description

Provides a description for the flow exporter.

destination

Export destination.

dscp

Optional DSCP value.

exit

Exits from the flow exporter configuration mode.

export-protocol

Export protocol version.

no

Negates the command or its default.

option

Selects option for exporting.

source

Originating interface for the net flow.

template

Flow exporter template configuration.

transport

Transport protocol.

ttl

Optional TTL or hop limit.

The switch exports data to the collector whenever a timeout occurs or when the flow is terminated (TCP Fin or Rst received, for example). You can configure the following timers to force a flow export:

  • Active timeout—The flow continues to have the packets for the past m seconds since the flow was created.
  • Inactive timeout—The flow does not have any packets for the past n seconds.
Related Tasks

Export Formats

The switch supports only NetFlow Version 9 export formats. NetFlow Version 9 export format provides the following features and functionality:

  • Variable field specification format
  • Support for IPv4 destination address export
  • More efficient network utilization

Note


For information about the Version 9 export format, see RFC 3954.

Monitors

A monitor references the flow record and flow exporter. You apply a monitor to an interface on the switch.

Note the following when applying a flow monitor to an interface:

  • If you apply a flow monitor in the input direction:
    • Use the match keyword and use the input interface as a key field.
    • Use the collect keyword and use the output interface as a collect field. This field will be present in the exported records but with a value of 0.
  • If you apply a flow monitor in the output direction:
    • Use the match keyword and use the output interface as a key field.
    • Use the collect keyword and use the input interface as a collect field. This field will be present in the exported records but with a value of 0.
Related Tasks

Samplers

If you are using sampled mode, you use the sampler to specify the rate at which packets are sampled.

Related Tasks

Supported Flexible NetFlow Fields

The following tables provide a consolidated list of supported fields in Flexible NetFlow (FNF) for various traffic types and traffic direction.

Note


If the packet has a VLAN field, then that length is not accounted for.


Field

Layer 2 In

Layer 2 Out

IPv4 In

IP v4 Out

IPv6 In

IPv6 Out

Notes

Key or Collect Fields

Interface input

Yes

Yes

Yes

If you apply a flow monitor in the input direction:

  • Use the match keyword and use the input interface as a key field.
  • Use the collect keyword and use the output interface as a collect field. This field will be present in the exported records but with a value of 0.

Interface output

Yes

Yes

Yes

If you apply a flow monitor in the output direction:

  • Use the match keyword and use the output interface as a key field.
  • Use the collect keyword and use the input interface as a collect field. This field will be present in the exported records but with a value of 0.

Field

Layer 2 In

Layer 2 Out

IPv4 In

IP v4 Out

IPv6 In

IPv6 Out

Notes

Key Fields

Flow direction

Yes

Yes

Yes

Yes

Yes

Yes

Ethertype

Yes

Yes

VLAN input

Yes

Yes

Yes

Supported only for a switch port.

VLAN output

Yes

Yes

Yes

Supported only for a switch port.

dot1q VLAN input

Yes

Yes

Yes

Supported only for a switch port.

dot1q VLAN output

Yes

Yes

Yes

Supported only for a switch port.

dot1q priority

Yes

Yes

Yes

Yes

Yes

Yes

Supported only for a switch port.

MAC source address input

Yes

Yes

Yes

Yes

Yes

Yes

MAC source address output

MAC destination address input

Yes

Yes

Yes

MAC destination address output

Yes

Yes

Yes

IPv4 version

Yes

Yes

Yes

Yes

IPv4 TOS

Yes

Yes

Yes

Yes

IPv4 protocol

Yes

Yes

Yes

Yes

Must use if any of src/dest port, ICMP code/type, IGMP type or TCP flags are used.

IPv4 TTL

Yes

Yes

Yes

Yes

 

IPv4 source address

Yes

Yes

IPv4 destination address

Yes

Yes

ICMP IPv4 type

Yes

Yes

ICMP IPv4 code

Yes

Yes

IGMP type

Yes

Yes

Field

Layer 2 In

Layer 2 Out

IPv4 In

IP v4 Out

IPv6 In

IPv6 Out

Notes

Key Fields continued

IPv6 version

Yes

Yes

Yes

Yes

Same as IP version.

IPv6 protocol

Yes

Yes

Yes

Yes

Same as IP protocol. Must use if any of src/dest port, ICMP code/type, IGMP type or TCP flags are used.

IPv6 source address

Yes

Yes

IPv6 destination address

Yes

Yes

IPv6 traffic-class

Yes

Yes

Yes

Yes

Same as IP TOS.

IPv6 hop-limit

Yes

Yes

Yes

Yes

Same as IP TTL.

ICMP IPv6 type

Yes

Yes

ICMP IPv6 code

Yes

Yes

source-port

Yes

Yes

Yes

Yes

dest-port

Yes

Yes

Yes

Yes

Field

Layer 2 In

Layer 2 Out

IPv4 In

IP v4 Out

IPv6 In

IPv6 Out

Notes

Collect Fields

Bytes long

Yes

Yes

Yes

Yes

Yes

Yes

Packet size = (Ethernet frame size including FCS - 18 bytes)

Recommended:

Avoid this field and use Bytes layer2 long.

Packets long

Yes

Yes

Yes

Yes

Yes

Yes

Timestamp absolute first

Yes

Yes

Yes

Yes

Yes

Yes

Timestamp absolute last

Yes

Yes

Yes

Yes

Yes

Yes

TCP flags

Yes

Yes

Yes

Yes

Yes

Yes

Collects all flags.

Bytes layer2 long

Yes

Yes

Yes

Yes

Yes

Yes

Default Settings

The following table lists the Flexible NetFlow default settings for the switch.

Table 4 Default Flexible NetFlow Settings

Setting

Default

Flow active timeout

1800 seconds

Flow timeout inactive

15 seconds

How to Configure Flexible NetFlow

To configure Flexible NetFlow, follow these general steps:

  1. Create a flow record by specifying keys and non-key fields to the flow.
  2. Create an optional flow exporter by specifying the protocol and transport destination port, destination, and other parameters.
  3. Create a flow monitor based on the flow record and flow exporter.
  4. Create an optional sampler.
  5. Apply the flow monitor to a Layer 2 port, Layer 3 port, or VLAN.
  6. If applicable to your configuration, configure a WLAN to apply a flow monitor to.

Creating a Flow Record

You can create a flow record and add keys to match on and fields to collect in the flow.

SUMMARY STEPS

    1.    configure terminal

    2.    flow record name

    3.    description string

    4.    match type

    5.    collect type

    6.    end

    7.    show flow record [name record-name]

    8.    copy running-config startup-config


DETAILED STEPS
      Command or Action Purpose
    Step 1 configure terminal


    Example:
    
                 
               
    Switch# configure terminal
    
    
     

    Enters the global configuration mode.

     
    Step 2 flow record name


    Example:
    Switch(config)# flow record test
    Switch(config-flow-record)# 
    
    
     

    Creates a flow record and enters flow record configuration mode.

     
    Step 3 description string


    Example:
    Switch(config-flow-record)# description Ipv4Flow
    
    
     

    (Optional) Describes this flow record as a maximum 63-character string.

     
    Step 4 match type


    Example:
    Switch(config-flow-record)# match ipv4 source address
    Switch(config-flow-record)# match ipv4 destination address
    Switch(config-flow-record)# match flow direction
    
    
     

    Specifies a match key. For information about possible match key values, see Flexible NetFlow Match Parameters.

     
    Step 5 collect type


    Example:
    Switch(config-flow-record)# collect counter bytes layer2 long
    Switch(config-flow-record)# collect counter bytes long
    Switch(config-flow-record)# collect timestamp absolute first
    Switch(config-flow-record)# collect transport tcp flags
    
    
     

    Specifies the collection field. For information about possible collection field values, see Flexible NetFlow Collect Parameters.

     
    Step 6 end


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

    Returns to privileged EXEC mode.

     
    Step 7 show flow record [name record-name]


    Example:
    Switch show flow record test 
    
    
     

    (Optional) Displays information about NetFlow flow records.

     
    Step 8 copy running-config startup-config


    Example:
    
                 
               
    Switch# copy running-config startup-config
    
    
     

    (Optional) Saves your entries in the configuration file.

     
    What to Do Next

    Define an optional flow exporter by specifying the export format, protocol, destination, and other parameters.

    Related Concepts

    Creating a Flow Exporter

    You can create a flow export to define the export parameters for a flow.

    SUMMARY STEPS

      1.    configure terminal

      2.    flow exporter name

      3.    description string

      4.    dscp value

      5.    destination { ipv4-address }

      6.    source { source type }

      7.    transport udp number

      8.    end

      9.    show flow exporter [name record-name]

      10.    copy running-config startup-config


    DETAILED STEPS
        Command or Action Purpose
      Step 1 configure terminal


      Example:
      
                   
                 
      Switch# configure terminal
      
      
       

      Enters the global configuration mode.

       
      Step 2 flow exporter name


      Example:
      Switch(config)# flow exporter ExportTest
      Switch (config-flow-exporter)#
      
      
       

      Creates a flow exporter and enters flow exporter configuration mode.

       
      Step 3 description string


      Example:
      Switch(config-flow-exporter)# description ExportV9
      
      
       

      (Optional) Describes this flow record as a maximum 63-character string.

       
      Step 4 dscp value


      Example:
      Switch(config-flow-exporter)# dscp 0
      
      
       

      (Optional) Specifies the differentiated services codepoint value. The range is from 0 to 63.

       
      Step 5 destination { ipv4-address }


      Example:
      Switch(config-flow-exporter)# destination 192.0.2.1
      
      
       

      Sets the destination IPv4 address or hostname for this exporter.

       
      Step 6 source { source type }


      Example:
      Switch(config-flow-exporter)# source gigabitEthernet1/0/1
      
      
       

      (Optional) Specifies the interface to use to reach the NetFlow collector at the configured destination. The following interfaces can be configured as source:

      • Auto Template—Auto-Template interface
      • Capwap—CAPWAP tunnel interface
      • GigabitEthernet—Gigabit Ethernet IEEE 802
      • GroupVI—Group virtual interface
      • Internal Interface—Internal interface
      • Loopback—Loopback interface
      • Null—Null interface
      • Port-channel—Ethernet Channel of interface
      • TenGigabitEthernet—10-Gigabit Ethernet
      • Tunnel—Tunnel interface
      • Vlan—Catalyst VLANs

       
      Step 7 transport udp number


      Example:
      Switch(config-flow-exporter)# transport udp 200
      
      
       

      (Optional) Specifies the UDP port to use to reach the NetFlow collector. The range is from 0 to 65535.

       
      Step 8 end


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

      Returns to privileged EXEC mode.

       
      Step 9 show flow exporter [name record-name]


      Example:
      Switch show flow exporter ExportTest 
      
      
       

      (Optional) Displays information about NetFlow flow exporters.

       
      Step 10 copy running-config startup-config


      Example:
      
                   
                 
      Switch# copy running-config startup-config
      
      
       

      (Optional) Saves your entries in the configuration file.

       
      What to Do Next

      Define a flow monitor based on the flow record and flow exporter.

      Related Concepts

      Creating a Flow Monitor

      You can create a flow monitor and associate it with a flow record and a flow exporter.

      SUMMARY STEPS

        1.    configure terminal

        2.    flow monitor name

        3.    description string

        4.    exporter name

        5.    record name

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

        7.    end

        8.    show flow monitor [name record-name]

        9.    copy running-config startup-config


      DETAILED STEPS
          Command or Action Purpose
        Step 1 configure terminal


        Example:
        
                     
                   
        Switch# configure terminal
        
        
         

        Enters the global configuration mode.

         
        Step 2 flow monitor name


        Example:
        Switch(config)# flow monitor MonitorTest
        Switch (config-flow-monitor)#
        
        
         

        Creates a flow monitor and enters flow monitor configuration mode.

         
        Step 3 description string


        Example:
        Switch(config-flow-monitor)# description Ipv4Monitor
        
        
         

        (Optional) Describes this flow record as a maximum 63-character string.

         
        Step 4 exporter name


        Example:
        Switch(config-flow-monitor)# exporter ExportTest
        
        
         

        Associates a flow exporter with this flow monitor.

         
        Step 5 record name


        Example:
        Switch(config-flow-monitor)# record test
        
        
         

        Associates a flow record with the specified flow monitor.

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


        Example:
        Switch(config-flow-monitor)# cache timeout active 15000
        
        
         

        Associates a flow cache with the specified flow monitor.

         
        Step 7 end


        Example:
        
                     
                   
        Switch(config-flow-monitor)#  end
        
        
         

        Returns to privileged EXEC mode.

         
        Step 8 show flow monitor [name record-name]


        Example:
        Switch show flow monitor name MonitorTest 
        
        
         

        (Optional) Displays information about NetFlow flow monitors.

         
        Step 9 copy running-config startup-config


        Example:
        
                     
                   
        Switch# copy running-config startup-config
        
        
         

        (Optional) Saves your entries in the configuration file.

         
        What to Do Next

        Apply the flow monitor to a Layer 2 interface, Layer 3 interface, or VLAN.

        Related Concepts

        Creating a Sampler

        You can create a sampler to define the NetFlow sampling rate for a flow.

        SUMMARY STEPS

          1.    configure terminal

          2.    sampler name

          3.    description string

          4.    mode {random}

          5.    end

          6.    show sampler [name]

          7.    copy running-config startup-config


        DETAILED STEPS
            Command or Action Purpose
          Step 1 configure terminal


          Example:
          
                       
                     
          Switch# configure terminal
          
          
           

          Enters the global configuration mode.

           
          Step 2 sampler name


          Example:
          Switch(config)# sampler SampleTest
          Switch(config-flow-sampler)#
          
          
           

          Creates a sampler and enters flow sampler configuration mode.

           
          Step 3 description string


          Example:
          Switch(config-flow-sampler)# description samples
          
          
           

          (Optional) Describes this flow record as a maximum 63-character string.

           
          Step 4 mode {random}


          Example:
          Switch(config-flow-sampler)# mode random 1 out-of 1024 
           

          Defines the random sample mode.

           
          Step 5 end


          Example:
          
                       
                     
          Switch(config-flow-sampler)#  end
          
          
           

          Returns to privileged EXEC mode.

           
          Step 6 show sampler [name]


          Example:
          Switch show sample SampleTest
          
          
           

          (Optional) Displays information about NetFlow samplers.

           
          Step 7 copy running-config startup-config


          Example:
          
                       
                     
          Switch# copy running-config startup-config
          
          
           

          (Optional) Saves your entries in the configuration file.

           
          What to Do Next

          Apply the flow monitor to a source interface, subinterface, VLAN interface, or a VLAN.

          Related Concepts

          Applying a Flow to an Interface

          You can apply a flow monitor and an optional sampler to an interface.

          SUMMARY STEPS

            1.    configure terminal

            2.    interface type

            3.    {ip flow monitor | ipv6 flow monitor}name [sampler name] { input |output }

            4.    end

            5.    show flow interface [interface-type number]

            6.    copy running-config startup-config


          DETAILED STEPS
              Command or Action Purpose
            Step 1 configure terminal


            Example:
            
                         
                       
            Switch# configure terminal
            
            
             

            Enters the global configuration mode.

             
            Step 2 interface type


            Example:
            Switch(config)# interface GigabitEthernet1/0/1
            Switch(config-if)#
            
            
             

            Enters interface configuration mode and configures an interface.

            Command parameters for the interface configuration include:

            • Auto— Auto-Template interface
            • Capwap—CAPWAP tunnel interface
            • GigabitEthernet—GigabitEthernet IEEE 802
            • GroupVI—Group Virtual interface
            • Internal Interface—Internal Interface
            • Loopback—Loopback interface
            • Null—Null interface
            • Port-channel—Ethernet channel of interface
            • TenGigabitEthernet—10- Gigabit Ethernet
            • Tunnel—Tunnel interface
            • Vlan—Catalyst VLANs
            • Range—Interface range

             
            Step 3 {ip flow monitor | ipv6 flow monitor}name [sampler name] { input |output }


            Example:
            Switch(config-if)# ip flow monitor MonitorTest input
            
            
             

            Associate an IPv4 or an IPv6 flow monitor, and an optional sampler to the interface for input or output packets.

             
            Step 4 end


            Example:
            
                         
                       
            Switch(config-flow-monitor)#  end
            
            
             

            Returns to privileged EXEC mode.

             
            Step 5 show flow interface [interface-type number]


            Example:
            Switch# show flow interface
            
            
             

            (Optional) Displays information about NetFlow on an interface.

             
            Step 6 copy running-config startup-config


            Example:
            
                         
                       
            Switch# copy running-config startup-config
            
            
             

            (Optional) Saves your entries in the configuration file.

             

            Configuring a Bridged NetFlow on a VLAN

            You can apply a flow monitor and an optional sampler to a VLAN.

            SUMMARY STEPS

              1.    configure terminal

              2.    vlan [configuration] vlan-id

              3.    ip flow monitor name [sampler name] {input |output}

              4.    copy running-config startup-config


            DETAILED STEPS
                Command or Action Purpose
              Step 1 configure terminal


              Example:
              
                           
                         
              Switch# configure terminal
              
              
               

              Enters the global configuration mode.

               
              Step 2 vlan [configuration] vlan-id


              Example:
              Switch(config)# vlan configuration 30
              Switch(config-vlan-config)#
              
              
               

              Enters VLAN or VLAN configuration mode.

               
              Step 3 ip flow monitor name [sampler name] {input |output}


              Example:
              Switch(config-vlan-config)# ip flow monitor MonitorTest input
              
              
               

              Associates a flow monitor and an optional sampler to the VLAN for input or output packets.

               
              Step 4 copy running-config startup-config


              Example:
              
                           
                         
              Switch# copy running-config startup-config
              
              
               

              (Optional) Saves your entries in the configuration file.

               

              Configuring Layer 2 NetFlow

              You can define Layer 2 keys in Flexible NetFlow records that you can use to capture flows in Layer 2 interfaces.

              SUMMARY STEPS

                1.    configure terminal

                2.    flow record name

                3.    match datalink {dot1q |ethertype | mac | vlan}

                4.    end

                5.    show flow record [name ]

                6.    copy running-config startup-config


              DETAILED STEPS
                  Command or Action Purpose
                Step 1 configure terminal


                Example:
                
                             
                           
                Switch# configure terminal
                
                
                 

                Enters the global configuration mode.

                 
                Step 2 flow record name


                Example:
                Switch(config)# flow record L2_record
                Switch(config-flow-record)#
                
                
                 
                Enters flow record configuration mode.

                 
                Step 3 match datalink {dot1q |ethertype | mac | vlan}


                Example:
                Switch(config-flow-record)# match datalink ethertype
                
                
                 

                Specifies the Layer 2 attribute as a key.

                 
                Step 4 end


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

                Returns to privileged EXEC mode.

                 
                Step 5 show flow record [name ]


                Example:
                Switch# show flow record
                
                
                 

                (Optional) Displays information about NetFlow on an interface.

                 
                Step 6 copy running-config startup-config


                Example:
                
                             
                           
                Switch# copy running-config startup-config
                
                
                 

                (Optional) Saves your entries in the configuration file.

                 

                Configuring WLAN to Apply Flow Monitor in Data Link Input/Output Direction

                SUMMARY STEPS

                  1.    configure terminal

                  2.    wlan wlan-name

                  3.    datalink flow monitor monitor-name {input | output}

                  4.    end

                  5.    show wlan wlan-name


                DETAILED STEPS
                    Command or Action Purpose
                  Step 1 configure terminal


                  Example:
                  Switch# configure terminal
                   

                  Enters global configuration mode.

                   
                  Step 2 wlan wlan-name


                  Example:
                  Switch (config) # wlan mywlan
                   

                  Enters WLAN configuration submode. For wlan-name, enter the profile name. The range is 1 to 32 characters.

                   
                  Step 3 datalink flow monitor monitor-name {input | output}


                  Example:
                  Switch (config-wlan) # datalink flow monitor flow-monitor-1 {input | output}
                   

                  Applies flow monitor to Layer 2 traffic in the direction of interest.

                   
                  Step 4 end


                  Example:
                  Switch (config) # end
                   

                  Returns to privileged EXEC mode.

                   
                  Step 5 show wlan wlan-name


                  Example:
                  Switch # show wlan mywlan
                   

                  (Optional) Verifies your configuration.

                   

                  Configuring WLAN to Apply Flow Monitor in IPV4 and IPv6 Input/Output Direction

                  SUMMARY STEPS

                    1.    configure terminal

                    2.    wlan wlan-id

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

                    4.    end

                    5.    show wlan wlan-name


                  DETAILED STEPS
                      Command or Action Purpose
                    Step 1 configure terminal


                    Example:
                    Switch# configure terminal
                     

                    Enters global configuration mode.

                     
                    Step 2 wlan wlan-id


                    Example:
                    Switch (config) # wlan 1
                     

                    Enters WLAN configuration submode. For wlan-id, enter the WLAN ID. The range is 1 to 64.

                     
                    Step 3 {ip | ipv6} flow monitor monitor-name {input | output}


                    Example:
                    Switch (config-wlan) # ip flow monitor flow-monitor-1 input
                     

                    Associates a flow monitor to the WLAN for input or output packets.

                     
                    Step 4 end


                    Example:
                    Switch (config) # end
                     

                    Returns to privileged EXEC mode.

                     
                    Step 5 show wlan wlan-name


                    Example:
                    Switch # show wlan mywlan
                     

                    (Optional) Verifies your configuration.

                     

                    Monitoring Flexible NetFlow

                    The commands in the following table can be used to monitor Flexible NetFlow.

                    Table 5 Flexible NetFlow Monitoring Commands

                    Command

                    Purpose

                    show flow exporter [broker | export-ids | name | name | statistics | templates]

                    Displays information about NetFlow flow exporters and statistics.

                    show flow exporter [ name exporter-name]

                    Displays information about NetFlow flow exporters and statistics.

                    show flow interface

                    Displays information about NetFlow interfaces.

                    show flow monitor [ name exporter-name]

                    Displays information about NetFlow flow monitors and statistics.

                    show flow monitor statistics

                    Displays the statistics for the flow monitor

                    show flow monitor cache format {table | record | csv}

                    Displays the contents of the cache for the flow monitor, in the format specified.

                    show flow record [ name record-name]

                    Displays information about NetFlow flow records.

                    show flow ssid

                    Displays NetFlow monitor installation status for a WLAN.

                    show sampler [broker | name | name]

                    Displays information about NetFlow samplers.

                    show wlan wlan-name

                    Displays the WLAN configured on the device.

                    Configuration Examples for Flexible NetFlow

                    Example: Configuring a Flow

                    This example shows how to create a flow and apply it to an interface:

                    
                    Switch# configure terminal 
                    Enter configuration commands, one per line. End with CNTL/Z.
                    
                    Switch(config)# flow export export1
                    Switch(config-flow-exporter)# destination 10.0.101.254
                    Switch(config-flow-exporter)# transport udp 2055
                    Switch(config-flow-exporter)# exit
                    Switch(config)# flow record record1
                    Switch(config-flow-record)# match ipv4 source address
                    Switch(config-flow-record)# match ipv4 destination address
                    Switch(config-flow-record)# match ipv4 protocol
                    Switch(config-flow-record)# match transport source-port 
                    Switch(config-flow-record)# match transport destination-port 
                    Switch(config-flow-record)# collect counter byte long
                    Switch(config-flow-record)# collect counter packet long
                    Switch(config-flow-record)# collect timestamp absolute first
                    Switch(config-flow-record)# collect timestamp absolute last 
                    Switch(config-flow-record)# exit
                    Switch(config)# flow monitor monitor1
                    Switch(config-flow-monitor)# record record1
                    Switch(config-flow-monitor)# exporter export1
                    Switch(config-flow-monitor)# exit
                    Switch(config)# interface tenGigabitEthernet 1/0/1
                    Switch(config-if)# ip flow monitor monitor1 input
                    Switch(config-if)# end 
                    
                    

                    Example: Configuring IPv4 Flexible NetFlow in WLAN (Ingress Direction)

                    The following example shows how to configure IPv4 Flexible NetFlow on WLAN ingress direction:

                    
                    Switch# configure terminal
                    Switch(config)# flow record fr_v4
                    Switch(config-flow-record)#	match ipv4 destination address
                    Switch(config-flow-record)#	match ipv4 source address
                    Switch(config-flow-record)#	match ipv4 protocol
                    Switch(config-flow-record)#	match ipv4 tos
                    Switch(config-flow-record)#	match ipv4 ttl
                    Switch(config-flow-record)#	match ipv4 version
                    Switch(config-flow-record)#	match wireless ssid
                    Switch(config-flow-record)#	collect wireless ap mac address
                    Switch(config-flow-record)#	collect counter packets long
                    Switch(config-flow-record)#	collect counter bytes long
                    Switch(config-flow-record)#	collect timestamp absolute first
                    Switch(config-flow-record)#	collect timestamp absolute last
                    Switch(config-flow-record)# exit
                    
                    Switch(config)# flow monitor fm_v4
                    Switch(config-flow-monitor)#	record fr_v4
                    Switch(config-flow-record)# exit
                    
                    Switch(config)#	wlan 1
                    Switch(config-wlan)#	ip flow monitor fm_v4 in
                    Switch(config-wlan)# end
                    
                    Switch# show flow monitor fm_v4 cache

                    Example: Configuring IPv6 and Transport Flag Flexible NetFlow in WLAN (Egress Direction)

                    The following example shows how to configure IPv6 and transport flag Flexible NetFlow on WLAN egress direction:

                    
                    Switch# configure terminal
                    Switch(config)#	flow record fr_v6
                    Switch(config-flow-record)# match ipv6 destination address
                    Switch(config-flow-record)#	match ipv6 source address
                    Switch(config-flow-record)#	match ipv6 hop-limit
                    Switch(config-flow-record)#	match ipv6 protocol
                    Switch(config-flow-record)#	match ipv6 traffic
                    Switch(config-flow-record)#	match ipv6 version
                    Switch(config-flow-record)#	match wireless ssid
                    Switch(config-flow-record)#	collect wireless ap mac address
                    Switch(config-flow-record)#	collect counter bytes long
                    Switch(config-flow-record)#	collect transport tcp flags
                    Switch(config-flow-record)# exit
                    
                    Switch(config)#	flow monitor fm_v6
                    Switch(config-flow-monitor)#	record fr_v6
                    Switch(config-flow-monitor)# exit
                    
                    Switch(config)#	wlan 1
                    Switch(config-wlan)#	ipv6 flow monitor fm_v6 out
                    Switch(config-wlan)# end
                    
                    Switch# show flow monitor fm_v6 cache

                    Note


                    On the switch, you cannot specify which TCP flag to collect. You can only specify to collect transport TCP flags.


                    Example: Configuring IPv6 Flexible NetFlow in WLAN (Both Ingress and Egress Directions)

                    The following example shows how to configure IPv6 Flexible NetFlow on WLAN in both directions:

                    
                    Switch# configure terminal
                    Switch (config)# flow record fr_v6
                    Switch (config-flow-record)# match ipv6 destination address
                    Switch (config-flow-record)# match ipv6 source address
                    Switch (config-flow-record)# match ipv6 hop-limit
                    Switch (config-flow-record)# match ipv6 protocol
                    Switch (config-flow-record)# match ipv6 traffic
                    Switch (config-flow-record)# match ipv6 version
                    Switch (config-flow-record)#	match wireless ssid
                    Switch (config-flow-record)#	collect wireless ap mac address
                    Switch (config-flow-record)# collect counter packets long
                    Switch (config-flow-record)# exit
                    
                    Switch (config)# flow monitor fm_v6
                    Switch (config-flow-monitor)# record fr_v6
                    Switch (config-flow-monitor)# exit
                    
                    Switch (config)# wlan 1
                    Switch (config-wlan)# ipv6 flow monitor fm_v6 in
                    Switch (config-wlan)# ipv6 flow monitor fm_v6 out
                    Switch (config-wlan)# end
                    
                    Switch# show flow monitor fm_v6 cache 

                    Additional References

                    Related Documents

                    Related Topic Document Title

                    Flexible NetFlow CLI Commands

                    Cisco Flexible NetFlow Command Reference (Catalyst 3850 Switches)

                    Flexible NetFlow Command Reference, Cisco IOS XE Release 3SE (Cisco WLC 5700 Series)

                    Error Message Decoder

                    Description Link

                    To help you research and resolve system error messages in this release, use the Error Message Decoder tool.

                    https:/​/​www.cisco.com/​cgi-bin/​Support/​Errordecoder/​index.cgi

                    Standards and RFCs

                    Standard/RFC Title

                    RFC 3954

                    Cisco Systems NetFlow Services Export Version 9

                    MIBs

                    MIB MIBs Link

                    All supported MIBs for this release.

                    To locate and download MIBs for selected platforms, Cisco IOS 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 website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

                    To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

                    Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

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

                    Feature Information for Flexible NetFlow

                    Release

                    Modification

                    Cisco IOS XE 3.2SE

                    This feature was introduced.

                    Cisco IOS XE 3.3SE

                    The following new commands were added:

                    • match wireless ssid
                    • collect wireless ap mac address