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How to enable flow on your Cisco IOS router

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This sample configuration is based on a Cisco 2800 series router. Other models may have slight configuration variations.

If you're collecting flow from multiple devices sharing the same public IP, you must configure chfagent to send flow to Kentik.

These instructions assume:

Access your router’s CLI

  1. Telnet or SSH into your Cisco router.
  2. Enter privileged mode by typing enable and entering your enable password.

Next, we’ll set up Netflow.

Set up the NetFlow sampler

Typical NetFlow deployments involve setting a sample rate so that we limit the amount of bandwidth NetFlow uses. For this example, we’ll assume we’re generating a flow packet for every 100 packets that traverse the router.

On your router, execute:

flow-sampler-map mysampler1
mode random one-out-of 100
exit

Enable NetFlow on the listening interface

In this step, we’ll instruct the device to generate flow packets for traffic that hits the ingress (receiving end) of the router’s WAN port.

On your router, execute:

interface FastEthernet0/1
ip flow ingress
ip route-cache flow
flow-sampler mysampler1
exit

Enable and configure export of NetFlow packets to AuvikFlow

In these final steps, we instruct the router on how to package and where to send flow packets.

On your router, execute:

ip flow-export source FastEthernet0/1
ip flow-export version 9
ip flow-export destination 208.76.14.247 20013

Exit configuration mode and commit the changes to memory.

end
write memory
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