What is the best way to monitor network load?

Question

Computer networks

There is a park of computers (35 pieces of Win7), 2 switches, a router and 2 servers (Win2k8). network topology as in the picture

Inside network 1GB/s outside 5MB/s. Switches are not controlled.
Users periodically either lose their network or lose speed when downloading files. As far as I know, some users (unknown who) often look at youtube to watch videos, in VK - streaming music / video or listen to online radio (I don't know about torrents).
Is there a monitoring system (preferably under Win) to find out which machine is currently downloading the channel?
OpManager (free) is now used as a monitoring system, but it has a limit of 10 machines.

Answer 1

managed switches +
Linux router port monitoring + traffic accounting using netflow

Answer 2

would you remove the loop

Answer 3

Put kerio on the computer, put the computer into a gap (it should have two set-woks on it, respectively) between the switches and the router. Even the most ancient (for Windows) version will show you everything.

Answer 4

If your router is completely stupid and does not even know how to SNMP, then nothing. If he knows how, then configure, for example, zabbix, and remove information via SNMP from the router. But this will show you the total load of the channel, but will not show who specifically loaded the channel to the eyeballs. To understand who exactly, you need a more intelligent router that, for example, netflow can do. And put the netflow collector on the network, watch what the channel loads.
A simpler implementation is to put http-proxy on the network. For a squid, for example, there are utilities that allow you to evaluate traffic on a user-by-user basis, such as sqstat.

Answer 5

If the return of statistics via netflow is supported (and it definitely is on Mikrotik), then give it and read it on the seen computer / server.

Answer 6

Why should users watch YouTube and VK? And that all 35 computers are hammered into the Internet. What about a router?

Answer 7

In your scheme, you can read / watch traffic only on the router.
What is the router model?
If it can be flashed to *WRT then there is still a chance!
P/S/
There are smart routers without *WRT firmware.