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Netflow and CPU load



"The advantage of using NetFlow is that it only requires little CPU load on the router itself ". This is from Paessler manual. I am trying to understand this statement. When you use Netflow, you are telling the router to monitor the flows and export it to the netflow collector. Doesn't it sound like the router is using CPU process rather than using little CPU load.


cisco cpu monitoring netflow sflow xflow

Created on May 22, 2014 6:39:33 PM

3 Replies




thank you very much for your KB-Post. Usually flow-based monitoring is compared to Sniffer-based monitoring. The trade-off with Sniffer-Based monitoring is indeed, the router does not need to do more than its normal job, and the monitoring solution needs to go into packets to check the traffic.
Flow-based monitoring is much less load-intensive for the monitoring solution, because it gets the results directly without needing to read packets. This is done by the router already, but the router needs to read the packets any way to do the routing in general. So with a little more CPU load on the router, it is able to forward statistics on the traffic to your monitoring solution.

best regards.

Created on May 23, 2014 12:24:46 PM by  Torsten Lindner [Paessler Support]



Back to the statement, "The advantage of using NetFlow is that it only requires little CPU load on the router itself". So with Netflow, it requires little CPU load than other management protocols, like SNMP, for example. Does it sound correct?

Created on May 28, 2014 1:31:05 PM



Again, the comparison is meant against Packet Sniffing, which on the other hand requires a lot of CPU on the host PC/Server of PRTG (much more than Netflow both on the router and the host server of PRTG). As both deliver the same level of detail in traffic monitoring.
SNMP also requires very little CPU on the router itself, but delivers far less details.

Created on May 28, 2014 1:37:00 PM by  Torsten Lindner [Paessler Support]

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