Flexible Netflow v9 on 4331

[amercer00]

This is my first, in what may be a series of netflow questions.

I just received a couple of ISR 4331 routers.  We are going to use these as internet routers for our company.

I would like to set up Flexible Netflow v9 with NBAR support to send to our Cisco Prime Infrastructure server.

The router will only have a port-channel interface on the inside and a single outside interface.

My question is: most documentation suggests monitoring ingress flows on both interfaces.  Would there be any advantages or disadvantages to just monitoring ingress and egress flows on a single interface if there are only going to be two interfaces and we are just doing simple internet routing.

Thanks,

Allen

[Vinit Jain · Accepted solution]

There are a few advantages of configuring egress flows:

- If you are having a WAN compression environment like WAAS, then it would be useful to configure egress flows. The egress flows are calculated after compression.

- If you will be running multicast, then it would make sense to have egress netflow as ingress netflow will have a destination interface of 0 as the router does not know the outgoing interface until the datagram is processed.

there are few others as well. it totally depends on what features you will be running in your network / router based on which you can configure ingress/egress netflows.

Hope this helps.

Regards

Vinit

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