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NBAR2 CPU Utilization

Does anybody have stats/info on how much of a CPU hit can be expected on ISR G2 routers when using NBAR2/DPI?

Alessio Andreoli

Hi Brad,
This almost entirely depends from the amount of different flow and the amount of traffic that your router has to manage. On an ISR G2 of mine, 2900 series, the CPU hit a max of 30% at the very beginning decreasing in a very short time as the service was identifying and classifying the traffic. In my case I had many different protocols and flows which nbar had to work with but I had a max of 4 Mbps throughput .

What kind of link do you have? Do you expect many different protocols passing by?

Hope this helps
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Hi Alessio, we would mainly be looking for Microsoft Lync traffic by inspecting the payload.  Are you saying once the service is identified then the CPU drops?  We will have links from 2-30Mbps.  We are also using SRE-910 for WAAS and I assume that increases the internal router throughput due to the hairpinning nature of the traffic flows.

Thanks, Brad.

Hi Brad,
In my case I decided to run the nbar discovery too. In the discovery phase you can have issues with the CPU. It seems to me that you intend to run NBAR2 only for classification from the last post. In this case I would no worry so much about the CPU since its job is due only with the amount of match statement and inspections you will set. I honestly would be surprised if an ISR G2 would have issues for some inspection as the ones you were describing above. Nevertheless, to make sure having at least 1G main memory could definitely help you out.


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