We are currently evaluating Netflow collector programs and have a generic question. Should I be able to see and account for total data transferred through netflow data? We have been working with a 1Gb sample to understand how Netflow is configured and reports. The reporting always seems to be much smaller that the data sample we are using. The basic setup we are using is as follows..
Netflow configured on a remote 3640 router. We have added ip route-cache flow to both the serial and Fast Ethernet interfaces. I am exporting to a server here at corporate where the collector software is running. I am showing datagrams being exported to my collector. I am copying the large test file from our corporate office to a server on the remote LAN. The transferr takes several hours and I would expect the total bytes reported transferred to be the same or larger that the sample file. We are however consistently seeing a smaller value.
Is there something that I am missing? Should I not be able to account for 100% of the traffic flowing in / out of either link? Management wants to make sure that if we are going to use these types of tools that the reporting be accurate.