When planning large installations of PRTG Traffic Grapher with many sensors (>100) or with high traffic (>10 Mbit), there are several parameters to take into account that influence the maximum number of sensors that can be monitored using one single PRTG instance.
Please see the Knowledge Base at www.paessler.com/support.
PRTG Traffic Grapher is an easy to use Windows software for monitoring and classifying bandwidth usage. It provides system administrators with live readings and long-term usage trends for their network devices. The most common usage is bandwidth usage monitoring, but you can also monitor many other aspects of your network like memory and CPU utilizations.