Keeping Track of Data Usage in GB Per Port

[Colton Conor <colton.conor () gmail com>]

I see in past news articles that cable companies are inaccurately
calculating customers data usage for their online GB of usage per month. My
question is how do you properly determine how much traffic in bytes a port
passes per month? Is it different if we are talking about an ethernet port
on a cisco switch vs a DSL port on a DSLAM for example? I would think these
access switches would have some sort of stat you can count similar to a
utility meter reader on a house. See what it was at last month, see what is
is at this month, subtract last months from this months, and the difference
is the total amount used for that month.

Why are the cable companies having such a hard time? Is it hard to
calculate data usage per port? Is it done with SNMP or some other method?

What is the best way to monitor a 48 port switch for example, and know how
much traffic they used?

https://gigaom.com/2013/02/07/more-bad-news-about-broadband-caps-many-meters-are-inaccurate/