The module automatically displays network graphs when you add a switch in NOC-PS and assign the ports to the corresponding servers. If you don't have your own switch, but your data center provides an API for querying bandwidth usage, you can use the "nocpsforwhmcs_customBandwidthGraph" function to query the data and create a graph.
This function refers exclusively to the output of the network graphs. To measure the bandwidth consumption as well, use the following function: External Bandwidth Collection Function
The function can be activated via customconfig.php, which can be found in the directory "/modules/servers/dedicated/"
/modules/servers/dedicated/
Adjust the code accordingly. The function must return either a link to an image (png/jpg/svg) or a base64 encoded image.