· Enable SNMP on the switch or router or device and also set the security feature to allow PRTG to access the device
· Find out which port (i.e. port number) the shared connection is attached to
· Start the "Add Sensor" wizard, choose SNMP, enter the IP and the SNMP login data of the router/switch
· In the checkbox list check the box of the port the shared connection is attached to and finish the wizard
· Now you will get a graph of traffic of the shared line
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.