Many DSL technologies implement an [[Asynchronous Transfer Mode|ATM]] layer over the low-level bitstream layer to enable the adaptation of a number of different technologies over the same link.
DSL implementations may create [[Networkbridging bridge(networking)|bridge]]d or [[routing|routed]] networks. In a bridged configuration, the group of subscriber computers effectively connect into a single subnet. The earliest implementations used [[DHCP]] to provide network details such as the [[IP address]] to the subscriber equipment, with [[authentication]] via [[MAC address]] or an assigned host name. Later implementations often use [[Point-to-Point Protocol|PPP]] over [[Ethernet]] or ATM ([[PPPoE]] or [[PPPoA]], also known as ''PPPoATM''), while authenticating with a userid and password and using PPP mechanisms to provide network details.
