ADSL Modems
ADSL Protocol Stack
A few popular ADSL protocol stacks are illustrated in figure below.
As can be seen from the figure above, the link-layer protocol is always ATM ALL5, no matter what protocol stack is used. The reason for that is that ATM meets the requirements of ADSL, which are high rates, handling timing–sensitive transmission of video and audio services.
ADSL modems
Network Architecture and Physical Connectivity
ADSL protocol Stack