Sampled NetFlow provides NetFlow statistics for a subset of incoming (ingress) IPv4 traffic on an interface.  Output Sampled NetFlow allows you to collect NetFlow statistics for a subset of outgoing (egress) IPv4 traffic on that interface.

The Output Sampled NetFlow feature is now available starting with IOS 12.0(24)S for IPv4 traffic on Cisco 12000 Series IP Service Engine (ISE) line cards.  In IOS 12.0(26)S, this feature was enhanced to report the input interface and support for the Cisco 12000 Series 4-Port Gigabit Ethernet ISE line card was added.

Which means that you can now export both ingress and egress Sampled NetFlow for Cisco 12000’s!

And with a NetFlow collector and analyzer you can collect these NetFlow packets and report on that data, getting more accurate outbound interface utilization information.

Configuring for Output Sampled NetFlow is relatively easy, as the global NetFlow configuration for this feature uses the same commands and settings with input sampled NetFlow.

To configure Output Sampled NetFlow on an interface, there are four basic steps:

1. enable
2. configure [terminal | memory | network}
3. interface type slot/port
4. ip route-cache flow [sampled [{input | output}]]
5. Repeat steps 3 and 4 for each interface.

After configuring the Cisco 12000 to export NetFlow, and then configuring the interfaces to export Output Sampled NetFlow, you can display the current content of the NetFlow cache with the following commands:

1. enable
2. attach slot-number
3. show ip cache verbose flow

See the NetFlow Cache Information Example in Cisco’s Output Sampled NetFlow document.

If you would like assistance with this NetFlow configuration, or are looking for a NetFlow traffic analyzer to collect the NetFlow packets, please contact us at (207) 324-8805, we’d be happy to work with you.

Joanne Ghidoni author pic

Joanne Ghidoni

Joanne is a Software Quality Assurance Engineer at Plixer. She has also held positions as Technical Support Engineer and Sales Engineer since joining Plixer in 2005. Prior to joining Plixer, Joanne has had numerous positions in the IT field, including data entry, computer operator, PC coordinator and support, mainframe programmer, and also Technical Support and web programmer at Cabletron Systems. In her spare time, Joanne enjoys traveling, always seeking out new and interesting places to visit.

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