It's a new feature I just discovered in Windows 8 Release Preview, that unlike Windows previous releases it also includes a Bandwidth Counter by default. I've few Wi-Fi routers set-up in my Hostel, and mostly I uses two, I am to check which Wi-Fi router has been transferred how much data. Read more to know how to check it.
So follow these steps to check you data usage router wise, I am not able to check it for Ethernet cable, but I'm sure it will work same there.
S1. Right Click on Networks Icon in System Tray.
S2. Right click on the router (or Adapter, whatever you call that), and select Show Estimated Data Usage.
S3. And its done a Single Click on that will show you estimated data transfer through that router.
In next article I will tel about what is the option Metered Connection