how to capture network traffic data?
You have two options
1. Enable NetFlow or some other flow option on a L3 network device like a switch or router. This will give you header information like source\destination IP address and some content data like the amount of information being transferred. Flow can be a good way to get a top level view of how much data is moving around
2. Enable a SPAN or mirror port on a managed switch. A SPAN\miror port allows you to get a copy of traffic associated with ports or VLANs and send it to another port where you can plug in a traffic analysis tool. Decent traffic analysis (or deep packet inspection) tools will give you information like source\destination, traffic volumes, application information and metadata like website or file name.
It all comes down to what your requirements are. If you just want a top level view with basic drilldown then flow may be an option. If you don't have flow options available or you want more detail for troubleshooting then a SPAN or mirror port will be your best option
Hope this helps,
Darragh
Usually network traffic data is done by using netflow or its counterparts like sflow and jflow
Solarwinds NTA does a good job
Lan Guardian is a more robust and comprehensive trafflic analyzer
