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User’s Guide – version 3.1.3 NetFlow Tracker
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Appendix 1: Device Configuration
This is a brief guide to setting up NetFlow on various types of device. Note that if your
device isn’t listed here it does not mean it is not supported by NetFlow Tracker; please
a
sk your device vendor for a guide to enabling NetFlow.
Enabling NetFlow Export/NDE on a Cisco Router or Layer 3
Switch
For more information on this subject, visit http://www.cisco.com/go/netflow. We
recommend that only people with experience in configuring Cisco devices follow these
steps. If in doubt, contact your network administrator or Cisco consultant. Note that if
you are running hybrid mode on a layer 3 switch you must configure IOS on the MSFC
and CatOS
on the Supervisor Engine. Native IOS also requires extra commands; these
are documented below.
Enabling Netflow Export on an IOS Device
In configure mode on the router or MSFC, issue the following to enable NetFlow Export:
ip cef
This enables Cisco Express Forwarding, which is required for NetFlow in most
recent IOS releases.
ip flow-export destination <address> 2055
Use the address of your NetFlow Tracker machine and one of the ports
configured in the Listener Ports
settings page. Port 2055 is monitored by
default.
ip flow-export source loopback 0
The source interface is used to set the source IP address of the NetFlow
exports sent by the router. NetFlow Tracker will make SNMP requests of the
router on this address. If you experience problems you can set the source
interface to an Ethernet or WAN interface instead of the loopback.
ip flow-export version 5 [peer-as | origin-as]
or
ip flow-export version 9 [peer-as | origin-as]
This sets the export version. Version 5 and Version 9 both support all of the
features NetFlow Tracker is capable of using; if you have a Native IOS switch
you may need to use version 9 to work around a bug – this is described below.
If your router uses BGP, you can specify that either the origin or peer ASs are
included in exports – it is not possible to include both.
Note that enabling or disabling NetFlow version 5 or version 9 (not version 1)
on a 12000 series router causes packet forwarding to stop for a few seconds
while the route processor and line card CEF tables are reloaded. To avoid
interruption of service to a live network, apply this command during a change
window, or include it in the startup-config file to be executed during a router
reboot.