Point-to-Point Protocol over ATM (PPPoA)

Point-to-Point Protocol over ATM, or PPPoA, encapsulates PPP connections for transmission across ATM networks and was mainly used on DSL lines. PPP handles authentication with username and password as well as the assignment of an IP address by the provider. Encapsulation takes place directly within ATM cells, which removes the additional Ethernet layer required by PPPoE and results in slightly less overhead. PPPoA was configured in the DSL router together with parameters such as VPI and VCI and the encapsulation method VC-MUX or LLC. The method was particularly common in the United Kingdom and other countries with ATM-based access networks. With the migration to pure IP networks and fibre, PPPoA is declining in importance but remains relevant in legacy installations.