I'm planning on enabling NetFlow on all my Routers( model 2600 through 7200).
I've been reading up on CPU impact and i found some interesting sites on the subject.
But one thing i'm not sure. The CPU utilization depends on how many flows the router sends out. Most of the documents refer to 10,000 flows. Does this amount depends on what i enable or is this the initial number of flows ?
Also what is the time interval for each flows.
I hope my question is clear.
Each flow is an IP connection, so it depends on traffic through the router and what interfaces you enable ip route-cache flow on.
I looked at a 7206 NPE225 with Netflow enabled on a single fast ethernet port running at about 4mb/s. There were 14,000 flows exported in about a minute. Router CPU is running about 45%. Lots of QOS with traffic shaping running on T1, multilink, and ethernet. Your mileage will of course vary -- but this is one example.
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