Then there is a second choke point where the cable company aggregates all of this data and there is another one when you actually reach the Internet.

FORBES: AT&T Data Cap Puts Squeeze On Netflix, AppleTV

If you use a cable modem, your first choke point is much closer to you since you share a maximum amount of bandwidth with other users in your neighborhood, which is why your data rate varies.

FORBES: AT&T Data Cap Puts Squeeze On Netflix, AppleTV