How to detect slow speed or if ether1 exceed limit of 50 gb?

Hello.
I want to detect if my internet uplink became slow. I have an limited traffic on ether1. If i exceed 50gb per month, than speed is dramaticly slows down at 256 kbps. now i have speed over 50mbits/s

if there is any way to detect by script slow speed or, somehow to monitor if my download traffic is less then 50gb?

Hi,

I know it’s an old thread, is this information still needed?
Do you have a quota of 50 gb on your download only or on total traffic (download + upload)