Before installing flow collectors, plan deployment based on location relative to the routers and network traffic monitoring requirements.
Location relative to the routers is the primary consideration in placement of a flow collector. The flow collector’s monitoring activities result in a continuous increase in network overhead traffic, which includes the flow packets coming from the routers and SNMP traffic generated when the flow collector polls the routers. It therefore may be necessary to place the flow collector at a location that avoids sending the additional traffic over critical areas of the network such as high-utilization WAN links.
For similar reasons, you should also consider the optimal location of the flow collector relative to the report server, because data will be sent to the server every monitoring interval.