Flexible NetFlow configuration in Cisco 4500 with Supervisor Engine 7-E and Cisco IOS XE

Catalyst 4500 series switches with Supervisor Engine 7-E and Cisco IOS XE Software Release 3.1.0 SG supports Flexible NetFlow. Hence we thought of sharing the configuration information with you.

The configuration of Flexible NetFlow in these switches is similar to the other regular Flexible NetFlow. Same 4 steps:
1)    Creating Exporter
2)    Creating Record
3)    Creating Monitor
4)    Associate the monitor to the interface.

However, supervisor 7-E does not support predefined records like traditional routers (record neflow ipv4 original-input). Hence it is compulsory that we should create a record.

You can configure the switch as mentioned below:

Exporter creation:

flow exporter NFAexporter // where to send the flow records
destination 192.168.1.1

Record creation:

flow record NFArecord // specifies the fields in the packet
  match datalink destination-vlan-id
  match ipv4 version
  match ipv4 tos
  match ipv4 protocol
  match ipv4 source address
  match ipv4 destination address
  match transport source-port
  match transport destination-port
  match interface output physical snmp
  match interface input physical snmp
  collect interface input snmp
  collect interface output snmp
  collect counter flows
  collect counter bytes
  collect counter packets
  collect timestamp sys-uptime first
  collect timestamp sys-uptime last

Monitor creation:

flow monitor NFAmonitor // here you can also specify how many unique flows records to collect
    record NFArecord
    exporter NFAexporter
    cache timeout active 1
    cache timeout inactive 30
    cache entries 1000

Associate the monitor to the interface

interface GigabitEthernet 0/1
     ip flow monitor NFAmonitor input

interface channel-group 1
    ip flow monitor NFAmonitor layer2-switched input // flow records collected even for bridged traffic.
  
Note: Selection of Layer 2 and Layer 3 packet fields in a single flow record definition is not allowed.

Once NetFlow is configured and flows reach the NetFlow Analyzer server the router will be auto detected and reports are generated.

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Praveen Manohar

NetFlow Analyzer Technical Team

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