One of several methods for transporting higher-level protocols over an ATM cloud, PPPoA is defined in RFC 2364.

PPPoA allows for encapsulation of most Layer 3 protocols into PPP frames which are then carried across an ATM PVC.

Since most traffic over ATM networks travels along considerably stable, static routes (e.g. MPOA, LANE, IP over ATM), PPPoA has very little use in campus or enterprise networks. The most frequent use of PPPoA is currently as one of the three major DSL traffic handling schemes -- the others being straight RFC 1483 bridging and RFC 2516 PPPoE -- all of which rely on RFC-1483 bridging at the lowest level.

The major advantage of PPPoA to ISPs and other DSL service aggregators is that connections are authenticated and accounted in similar ways to dialup PPP connections. This means that ISPs can continue to use their RADIUS, TACACS+ or other AAA solutions to manage DSL subscribers. PPPoE has this advantage as well, but with the additional traffic overhead of Ethernet frames (26 bytes per frame add up quickly).

To a DSL end-user, a PPPoA connection is typically terminated in one of two methods:

• A CPE unit which includes router functionality allows the user to connect the DSL directly to a LAN (or a workstation with an Ethernet adapter). The router removes IP packets from Ethernet frames and transmits them via the PPP connection to the ISP. These devices include Cisco 678 and Efficient Networks Speedstream 5660.
• An internal (ISA or PCI) or external (USB) adapter provides the user (transparently) with an ATM interface. A PPP connection is made in the normal method of the operating system such as Windows' Dial Up Networking (DUN). Examples of these units are Efficient Networks Speedstream 4060 and Alcatel Speed Touch PC.